tag:blogger.com,1999:blog-68757718131226163912024-03-04T23:27:30.584-08:00chevy spark ev UNOFFICIAL blogsparkevhttp://www.blogger.com/profile/04362518920979349841noreply@blogger.comBlogger43125tag:blogger.com,1999:blog-6875771813122616391.post-37320122503145055122017-05-30T16:10:00.000-07:002017-06-17T15:01:15.873-07:00Year of DC fast charging and battery degradation estimateAfter about 1 year of SparkEV ownership, I started to log DCFC data for about a year, which resulted in 104 data points, average of exactly 2 DCFC per week. Coincidence or fake, you be the judge. I mostly use ABB chargers, which show percent, energy in kWh, and time.<br />
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Recorded from ABB charger:<br />
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starting battery in %<br />
ending battery in %<br />
total energy in kWh<br />
elapsed time<br />
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Car shows miles. Recorded from car:<br />
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starting miles<br />
ending miles<br />
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I started with recording the date and time and ambient temperature, but I got lazy and those records are spotty (only for the first one). But above data have been recorded on almost every DCFC session.<br />
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<b>Look of raw data</b><br />
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What do you do with so much data? Why you generate figures, of course. We are visual creatures, and we love curvy figures. This is why strip clubs are profitable; we go there to stare at curvy figures! As with strippers, we’d rather look at real data, not fake ones (or pretend fakes are real). One way to do that is to look at the data from a known source. In this case, energy in kWh and charge time in minutes are strictly from the charger, and independent of the car. That’s what I plot first.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhijRtuFV0lZNx5YmkmP0otpoPjalydU6HvhxR7ELzsFw8MJD407g1iA6prxAoN9o5il9Qw3_KiO3sTpKu_Gu3LZIRzFerkcpwUfn37guieJ0x9vFEYkiAEzwRnkruDdj384tLEZwpHEWhG/s1600/sparkev_year_of_dcfc_01_charge_energy_vs_charge_time.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="420" data-original-width="560" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhijRtuFV0lZNx5YmkmP0otpoPjalydU6HvhxR7ELzsFw8MJD407g1iA6prxAoN9o5il9Qw3_KiO3sTpKu_Gu3LZIRzFerkcpwUfn37guieJ0x9vFEYkiAEzwRnkruDdj384tLEZwpHEWhG/s1600/sparkev_year_of_dcfc_01_charge_energy_vs_charge_time.gif" /></a></div>
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All those years of strip club training to spot fakes paid off as I can spot bimodal distribution right away in this graph. You can see that there are two (or more) distinct curves taking shape. This sets the tone for this blog post: major judgment call is based on strip club training. Therefore, this blog post should be treated as such.<br />
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<span style="font-size: x-large;"><b>All data and analysis are completely subjective, probably wrong, and should not be trusted!</b></span><br />
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I will give the raw data and source code to analysis, so you can judge for yourself how valid these may be. I find some strippers very pretty, so you may find the data and analysis presented here just as pretty.<br />
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<b>Spotting fake</b><br />
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To get a better understanding, I infer average charge power (energy per unit time, aka division) over samples to see if there’s been any variations over time. <br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi6F0bsKQ_AKUK0XJPGAyY-3sHomPFISvBh81Cg5L4iakNRlLGcvgGgtwWFgr2TAOWqtiMRw52Ag9jWQLY8CG1EUfEoI2IyXHRrnCgABWdVbJjbTQ8CxTHl8yZdjyxZSvz3MeMRTmAUCzBL/s1600/sparkev_year_of_dcfc_02_charger_power_vs_time.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="420" data-original-width="560" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi6F0bsKQ_AKUK0XJPGAyY-3sHomPFISvBh81Cg5L4iakNRlLGcvgGgtwWFgr2TAOWqtiMRw52Ag9jWQLY8CG1EUfEoI2IyXHRrnCgABWdVbJjbTQ8CxTHl8yZdjyxZSvz3MeMRTmAUCzBL/s1600/sparkev_year_of_dcfc_02_charger_power_vs_time.gif" /></a></div>
Indeed, you can see a sharp increase in average power at about sample 35. What happened? I did not change my charging locations or driving pattern, so it’s probably not the car or me. But ABB chargers used to update the data every second, and they changed to update every 10 seconds some time in the past. I speculate that change in ABB chargers occurred at about sample #35.<br />
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Then I go back to plotting charger-only data of energy vs time for samples 1 to 34 and 35 to end.<br />
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Plots are lot better, though samples 35 to end looks like there’s yet another pattern. It could be that some DCFC units are not up to snuff as others?<br />
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But a bigger question is, which data is closer to real, samples 1 to 34 or 35 to end? Apparently, I need more strip club training to spot the fake! Or in this case, I turn to even more powerful tool: guessing.<br />
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I have another piece of data to help determine which may be real, which is the efficiency reported by the car. Over the course of over 19K miles, SparkEV shows 5.3 mi/kWh. 16K miles shown, but it hasn't changed.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh_rpTN6m6_t2knpy0udrbIQihLe3GqElxU1xQhLZCJbumLXLffeQnrIvNgDor_rPbPTeI4T4bKmshIAvN5zQ2zLI69rLxfnvUaKqekv5Q6_piifVOuK03GbYoYpNJE4zSA2CM8ILYhFm9d/s1600/mi_per_kwh_after_16kmiles.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="320" data-original-width="520" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh_rpTN6m6_t2knpy0udrbIQihLe3GqElxU1xQhLZCJbumLXLffeQnrIvNgDor_rPbPTeI4T4bKmshIAvN5zQ2zLI69rLxfnvUaKqekv5Q6_piifVOuK03GbYoYpNJE4zSA2CM8ILYhFm9d/s1600/mi_per_kwh_after_16kmiles.gif" /></a></div>
Since we have miles estimate for each DCFC session (ending miles minus starting miles, both reported by the car), and we have energy (kWh reported by the charger), we simply divide the values to get mi/kWh estimate for each charge session (or previous drive session since miles are determined based on past driving cycle). It’s combining two uncalibrated sources, but what the heck, it’s close enough for free blog post!<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj68k2xR5we0dWBvDg4tJTYqHKITeO-4KARcJ8_lr63VakJxZIDrDVoaMJNQv_xRZWR6LeG7s6YZne3MkkKZbIxUQCoJgpksAY0hAZZdfWClEOv_mN7rgJnDRM_w37N5sULau8CmCcBe74C/s1600/sparkev_year_of_dcfc_04_efficiency_over_time.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="420" data-original-width="560" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj68k2xR5we0dWBvDg4tJTYqHKITeO-4KARcJ8_lr63VakJxZIDrDVoaMJNQv_xRZWR6LeG7s6YZne3MkkKZbIxUQCoJgpksAY0hAZZdfWClEOv_mN7rgJnDRM_w37N5sULau8CmCcBe74C/s1600/sparkev_year_of_dcfc_04_efficiency_over_time.gif" /></a></div>
You can clearly see that samples 1 to 34 are much higher than later samples. Which is fake?<br />
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Here, we look at the average for each. For samples 1 to 34, average is about 5.75 mi/kWh (cyan line) while the rest are about 4.9 mi/kWh (magenta line). But remember, DCFC is not 100% efficient. From previous blog post about SparkEV being the most efficient car in world history, we estimate about 94% efficiency for DCFC.<br />
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<a href="http://sparkev.blogspot.com/2017/02/sparkev-is-most-efficient-car-in-world.html">http://sparkev.blogspot.com/2017/02/sparkev-is-most-efficient-car-in-world.html</a><br />
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Then we plot 5.3 mi/kWh (green line) and 94% of that (~5 mi/kWh, red line). It seems first set of data to sample 34 is fake. It’s a not a problem; with advances in science, Dr. SparkEV will simply perform a surgery to make it come into shape as the real data so that power vs samples look pretty. There’s no fake data here!<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiFxAp-TeL4RQIic1161dkG6smuJWMOkoPTrnrsEaxMMYh1S3Ci84ageOyv6wWnNDZ-a7aMbgV1gKhgE3fJOsSNvf6io1AjFlEyuh-IXVGp8I4s606ic7izL0BeAAvtMjw19iNcEyULpiiO/s1600/sparkev_year_of_dcfc_05_charge_power_vs_time.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="420" data-original-width="560" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiFxAp-TeL4RQIic1161dkG6smuJWMOkoPTrnrsEaxMMYh1S3Ci84ageOyv6wWnNDZ-a7aMbgV1gKhgE3fJOsSNvf6io1AjFlEyuh-IXVGp8I4s606ic7izL0BeAAvtMjw19iNcEyULpiiO/s1600/sparkev_year_of_dcfc_05_charge_power_vs_time.gif" /></a></div>
As with plastic surgery, making the data look good is subjective. One might think that since we know the average of both sets of data (samples 1 to 34 and 35 to end), simple scaling based on averages may work. Indeed, that’s what I did initially, but that still looked off. Best evenness is obtained by much trial and error, and that is shown in graph above. We will use this new “surgeried” data for further analysis.<br />
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<b>Curvy figures with angular jags</b><br />
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There are many things one can infer from the data. First is various raw data over charge time, and some linear fitting.<br />
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From the raw data, you can see that greater than 20 minutes of charging time result in lower percent and energy than a straight line fit. This is expected since SparkEV would taper charge after 80%, and 20 minutes would get you above 80%.<br />
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The curve fitting is performed on data that had ending percent less than 85%, not on the entire data. Why not 80%? We’ll go over that in next section. But for now, you can see the linear fit shows 20 minutes of charging would give about 4% per minute (80% in 20 minutes), 3.76 miles per minute (75 miles in 20 minutes), 0.74 kWh per minute (14.8 kWh from charger in 20 minutes). Compared to L2 charging of 0.05 kWh from charger per minute (3.3 kW charger), DCFC is almost 15 times faster!<br />
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<b>Charge taper</b><br />
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To get a better picture of charge taper, I plot average power (energy in kWh divided by charge time in hours) vs % charged. When the battery is above 80%, I would expect the power to dip, because that’s what I see at the charger if I’m staring at it.<br />
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As you can see, there aren’t too many charge sessions that ended below 80% (blue dots). This is one reason why 85% was chosen as the demarcation point for fitting the raw data in previous plot: not enough points below 80%.<br />
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In addition, I only recorded the total power after charging is done. That means all the readings are average of the entire charge session, not just to 80%. For example, had I started at 1% and charged to 90%, average power would be very high (45 kW?). But if I started at 80% and charged to 90%, average power would be much lower (25 kW?). <br />
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And the most relevant reason is that 85% gave pretty good looking fit. I could’ve used 86% of 84%, but they just didn’t look as good. There’s no fake data, just pretty data!<br />
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For total charge percent (red dots), the taper starts roughly about 70%. That means I typically started charging at over 10% battery and stopped when charge taper became significant beyond 80% state of charge.<br />
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For ending charge percent (blue dots), it shows bit over 80% begins to taper. Most charge sessions end above 80%, but less than 90%. What this shows is that I charge near full power most times, not plug in when I already have 80% battery and make others wait while the car has severely tapered, unlike some (many) Nissan Leaf drivers plugged in when they already have 90%.<br />
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For few weeks (maybe few months), I was experimenting to see if I can only use DCFC without home charging as if I’m living in an apartment without the ability to charge at home or work. I did not want to inconvenience others, so I disconnected as soon as I saw another EV pull up. This is why there are several charge cycles less than 50% change (red dots), and most of those are above 42 kW on average, full power without taper. In other words, no one waited for me needlessly, and I went out of my way to be polite to other EV.<br />
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<b>Overstuffing battery capacity</b><br />
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A question I had is if one sees reduced battery capacity as it’s charged fuller. For example, higher percent could use more cell balancing or more intensive battery management, thus slowing down the percentage as kWh from the charger increase.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZ8jVorAMQ0rIt6c5EkN-1DQkclPjFPhtq4ceO8U4uUwv1n3D73wyjr60efZn2d56OkUfmLXlw4EZiEx1t15um1ixc9ifXhQmandvo-xk7F2cZwdydHU68nCLaXtea9TySd1QcOWtTjFfJ/s1600/sparkev_year_of_dcfc_08_battery_capacity_vs_pct.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="420" data-original-width="560" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZ8jVorAMQ0rIt6c5EkN-1DQkclPjFPhtq4ceO8U4uUwv1n3D73wyjr60efZn2d56OkUfmLXlw4EZiEx1t15um1ixc9ifXhQmandvo-xk7F2cZwdydHU68nCLaXtea9TySd1QcOWtTjFfJ/s1600/sparkev_year_of_dcfc_08_battery_capacity_vs_pct.gif" /></a></div>
It’s not clear if there’s any kind of correlation. Certainly, temperature may have something to do with it as well as how long ago the cells were balanced. Unfortunately, I do not have access to battery temperature, so I never recorded the data. I call this inconclusive, though leaning towards higher charging (at least not to 100%) has no effect in capacity.<br />
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However, there seem to be some erroneous data. Some show battery capacity more than 20 kWh, and one shows almost 15 kWh. Obviously, those are bad data. My suspicion is that I was looking at some pretty girl nearby, and recorded the wrong data!<br />
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I count about 6 data points too high and one data point too low, so they will be discarded.<br />
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<b>Energy for percent</b><br />
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Now that I know what data to discard, I can plot other data, which is charger energy (provided by charger) vs percent charged (provided by the car). If charge taper did not expend extra energy, it should be a straight line.<br />
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Here, we can infer some interesting data. First, it fits in a straight line, even the 90% charge, so charging more would not waste energy. At 100%, battery would be 17.6 kWh (red line fitting at 100%), which is 18.7 kWh from the charger. This is not 18.4 kWh, supposed battery capacity of SparkEV! What happened?<br />
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Remember, I started logging the data after one year to second year, so this represents average battery capacity for day 365 to day 730 of car ownership. As such, it should be less than the peak advertised battery capacity.<br />
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<b>Battery capacity degradation</b><br />
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Now comes the biggie: battery capacity over time. We know the average battery capacity for the year that I recorded the data, but how did it degrade? Unfortunately, I did not log the day/time, so I can only guess even distribution of charge events. Then we plot this for each data set. Remember, sample 0 (shown as sample 1 in plot, damn you Matlab!) is one year after I started driving SparkEV.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgR8jD92TbJmqlBY6DyBgPOz8jZbpGffje9KEv4zJygdaqXLz39-wW4WyShwbp2U0WsXBHBJppDoNeqzRuReXrnz7qH7Y4hGRqs2vvcgawzUtNtzSKBnP-Zs6bYftnJ0brfwxqsY5txD5fp/s1600/sparkev_year_of_dcfc_10_battery_capacity_over_1_year.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="420" data-original-width="560" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgR8jD92TbJmqlBY6DyBgPOz8jZbpGffje9KEv4zJygdaqXLz39-wW4WyShwbp2U0WsXBHBJppDoNeqzRuReXrnz7qH7Y4hGRqs2vvcgawzUtNtzSKBnP-Zs6bYftnJ0brfwxqsY5txD5fp/s1600/sparkev_year_of_dcfc_10_battery_capacity_over_1_year.gif" /></a></div>
Note the same high and low samples discarded based on previous findings.<br />
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The curve fit is done using linear fit and exponential fit, and they look like they are on top of each other. Even if the degradation is exponential decay, such small number of samples would make it seem indistinguishable from linear. I suspect the actual degradation is exponential rather than linear, like much of natural processes. But linear is lot easier to interpret for us simple minds. We will discuss long term fitting later.<br />
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The graph shows that the battery was 18.1 kWh at beginning of the recording (1 year of degradation), and degrading about 0.007 kWh each sample (about half week). At the end of recording (2 years of degradation), battery has 17.3 kWh remaining. Average is about 17.7 kWh, which is close 100% capacity found in previous graph.<br />
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I took a more accurate reading of battery capacity about 2 months after recording started, and that showed 18.05 kWh. More recent reading showed 17.3 kWh, so it seems the battery is degrading according to the estimate. I will discuss battery capacity in more detail in some future blog post.<br />
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Of course, we’re looking at a tiny sliver of time, the reason why exponential decay and linear are practically the same.<br />
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<b>Battery capacity degradation extrapolated</b><br />
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Now that we can see how well the data fits over samples, we can extrapolate for many years. Recall that the data collection started a year after getting the car and 104 samples (about 2 samples per week) over a year, and only estimated to be evenly spaced two DCFC charging per week. But that’s close enough to real usage for this blog post (you didn't pay for it, did you?), and we extrapolate for many years using the same battery degradation equation from before.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgIXq8Ycf1XRePjsd1x4TrOzjiHihLClBhMFR1yye2_d_dGVnSC8O0LFhBLzBhgsDS_mcPfae68pZc-kkB8uUSG_a4M14HLmVB8Sft1_3-JWTP4uM_J6Pjxti2ye6fNI93jNFRaPEZP_77H/s1600/sparkev_year_of_dcfc_11_battery_capacity_over_time.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="420" data-original-width="560" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgIXq8Ycf1XRePjsd1x4TrOzjiHihLClBhMFR1yye2_d_dGVnSC8O0LFhBLzBhgsDS_mcPfae68pZc-kkB8uUSG_a4M14HLmVB8Sft1_3-JWTP4uM_J6Pjxti2ye6fNI93jNFRaPEZP_77H/s1600/sparkev_year_of_dcfc_11_battery_capacity_over_time.gif" /></a></div>
The years on x-axis are true years starting when the car was new. I extrapolated the data collected between year 1 to year 2 both ways, before data collection began (beginning of year 1 to year 0) and after last data collected (end of year 2 to end). It seems my car had 18.87 kWh available in the beginning (or did it?)<br />
<br />
One thing clear is that curves (green, blue, red) diverge significantly after about year 5. That means you won’t be able to tell which path the battery degradation is following until then. But even then, noisy data will make it hard to tell maybe until 5% divergence; raw data is fluctuating about 1kWh total, so 0.5 kWh deviations would be apparent. Between blue and green, that occurs about year 8, the end of the warranty period. Between blue and red, that occurs about year 5.<br />
<br />
Linear decay (blue) assumes same number of charging per given time interval for all time, 104 DCFC per year plus X number of home charging. But if I’m to keep driving same number of miles per year, there will be more charging. Simply, each charge cycle would be capable of fewer miles due to degraded battery, and more charging is needed to drive the same number of miles.<br />
<br />
More charging per mile means more degraded battery. I plot this scenario as red plot. I made two known points to intersect: beginning of year 0 and ending of year 2. I suppose I could've made the intersection to be beginning of year 1 (first data collected) to end of year 2 (last data collected), but I chose year 0 and year 2 since they would generate worse degradation plot. Seeing how they are really close before about year 5 anyway, it probably won't make much difference either way.<br />
<br />
The y-axis is divided into 10, so each represents 10%. To make it even easier to read, cyan line is 65%, and magenta line is 50%.<br />
<br />
<b>Life of a car</b><br />
<br />
MrDRMorgan from SparkEV forum found that SparkEV battery warranty is to 65% in 8 years and 100K miles. If one follows linear trend (same number of charging per year, fewer miles driven each year), 65% would be reached well after eighth year.<br />
<br />
If one has fewer charging events as time goes (much fewer miles), and follow the exponential decay curve (green plot), it could take bit over 10 years before hitting 65%. Unfortunately, this isn’t likely for most people, though some may get tired of frequent charging that they drive fewer miles with increasing degradation.<br />
<br />
BUT if one drives the same number of miles by increasing the number of charging events, it could hit 65% in seventh year. That could trigger the warranty service. It’s unknown what Chevy will do if that happens: they may not replace the battery with a new one, but one that is barely above 65% that will take it to eighth year. In any case, this is an unpleasant scenario to avoid.<br />
<br />
One might think that this is awful, but it may not be so bad.
Biggest reason is that I have no idea what is the major contributor to
capacity degradation. It may not be solely due to charge-discharge
cycles that the red plot is based on. For most (all?) LiIon batteries, just letting it sit there would also cause degradation. If the major cause of degradation is time, then the degradation would follow blue curve (probably bit more since there'd be more charge-discharge cycles).<br />
<br />
How do you tell if the major contributor to degradation is time or charge-discharge cycles? If there are same model year cars with much different number of miles (more or less charge cycles) and in similar climate and "abuse" that show similar degradation, that would indicate more of time dependence. Unfortunately, detailed battery capacity is hard to come by, not to mention finding other SparkEV with same usage pattern as mine.<br />
<br />
Even if the battery has degraded beyond 35% (65% remain), car would still be usable. How much is it usable depends on how far the DCFC stations are spaced. Currently in SoCal, DCFC between San Diego to Orange County is about 30 miles apart, which means car must be capable of 40 miles (10 miles as margin). That’s about 50% capacity, although slow driving (55 MPH) could make it 40%.<br />
<br />
Assuming no warranty service and looking at 50%, that occurs at about year 9 if driven same number of miles as current (red plot), year 12.5 if keeping the same number of charge events (linear, blue plot), and greater than year 15 if charging is reduced (fewer miles per year, green plot).<br />
<br />
From my first blog post, I estimated the car to last 10 years in amortizing purchase price / lease price.<br />
<br />
<a href="http://sparkev.blogspot.com/2015/05/first-of-all.html">http://sparkev.blogspot.com/2015/05/first-of-all.html</a><br />
<br />
It seems it can barely reach 10 years with careful driving.<br />
<br />
But remember what I wrote earlier in this blog post: <br />
<br />
<span style="font-size: x-large;"><b>All data and analysis are completely subjective, probably wrong, and should not be trusted!</b></span><br />
<br />
<b>Motivation</b><br />
<br />
You might be wondering what prompted me to keep such meticulous data keeping after 1 year of use. I can assure you, it wasn’t because I wanted to put up with even more hassle of writing down charge data.<br />
<br />
I use eVgo almost exclusively for DCFC. They give no receipt, and they didn’t even give a record of charging when I started using them in mid 2015. Couple of months later, they started sending emails of history of my usage, which they do about once a month. Fair enough.<br />
<br />
Then about 1.5 year ago, I started receiving two emails that showed two different billing. There were much overlap in session records, and they replied to my inquiry that they were charging my credit card correctly. The rep replied that they would fix it, but it went on for many more months.<br />
<br />
And then they charged me $5 out of the blue in addition to my monthly fee (including double billing)! I again inquired about the charge, to which the rep replied it was for something or another. I again asked them that there must be some error since I’m on $15/mo OTG plan and there’s no record of this $5 usage, but I never heard back from the rep.<br />
<br />
I’m not happy about the poor customer service, but I didn’t bother pursuing the matter further as that could result in even more problems with billing or even bigger $$ charged to my account. Evgo is about the only DCFC available in my area, and losing that service via billing problem would mean unable to drive the car except to supermarkets. When you live in a glass house (or drive in glass charging infrastructure), it’s best not to throw stones.<br />
<br />
From that point on, I decided to keep a record of DCFC sessions. Even if I can’t do anything about getting my money back, at least I’d know how much I’m getting ripped off. But keeping record has side benefits, which resulted in this wonderful blog post. Things don’t happen for a reason, but one can always turn a lemon into lemonade.<br />
<br />
<b>Appendix</b><br />
<br />
As before, analysis is done using Octave. Copy-paste the code below to a text file and run it with Octave or Matlab. I keep it simple, and made it somewhat modular so I can reuse this with my next EV. Side benefit to that is that it can easily be used with other EV, too. As usual, sparse commenting.<br />
<br />
<span style="font-family: "courier new" , "courier" , monospace;">close all; clear;
<br /><br />%raw data
<br />pct_start = [13 26 52 30 22 34 32 12 21 29 10 5 12 27 15 45 31 8 10 20 20 52 16 54 11 5 13 23 16 45 16 26 23 6 19 9 40 21 13 10 15 25 16 14 40 11 11 66 14 18 55 17 32 23 27 27 37 16 12 52 25 35 17 34 11 23 16 7 29 14 40 39 32 20 10 16 28 36 31 34 13 16 20 11 22 16 15 18 10 16 56 14 27 33 48 23 10 34 21 13 18 13 16 51];
<br />miles_start = [12 28 50 33 24 31 32 14 23 29 12 5 12 27 16 42 31 8 11 19 19 52 17 52 12 6 13 24 17 45 16 23 24 7 19 19 37 20 13 10 16 25 16 14 39 10 10 65 13 19 53 16 32 20 27 26 39 16 13 47 24 34 19 32 10 22 17 7 29 15 42 32 32 19 9 16 28 36 31 32 13 16 18 11 20 12 15 16 10 17 51 14 27 31 51 22 9 38 20 11 14 13 17 49];
<br />pct_end = [85 82 87 85 70 86 84 83 61 85 86 85 93 89 68 85 84 83 87 83 64 84 69 83 87 90 83 81 81 85 94 92 94 94 84 85 77 93 89 85 83 84 83 83 81 90 80 82 83 80 83 89 84 86 83 83 79 85 76 84 83 85 83 86 85 77 75 95 82 50 85 80 81 82 81 88 89 81 87 85 85 82 84 90 86 89 84 80 81 78 83 81 82 82 84 88 83 80 81 85 85 85 85 83];
<br />charge_kwh = [12.09 9.54 6.02 8.75 8.2 8.74 8.85 12.18 6.73 9.5 12.6 13.24 13.57 10.53 8.82 6.81 8.87 12.76 13.1 10.86 7.46 5.45 8.82 4.74 14.25 16.15 11.53 9.63 10.9 6.74 13.12 11.13 13.49 16.33 12.24 12.21 6.83 13.53 14.91 14.36 13 11.37 13 13.12 7.79 15.12 13.11 3.25 13.03 11.6 5.4 14 9.85 12 10.13 10.88 7.79 12.87 11.56 6 10.75 9.12 12.17 9.65 13.58 10.07 10.78 16.35 10.03 6.73 8.43 7.5 9.26 11.5 13.03 13.35 11.46 8.43 10.4 9.79 13.45 12.19 12.22 14.56 11.88 13.25 13 11.62 13.03 11.6 5.37 12.28 10.2 9.33 6.78 11.98 13.82 8.57 10.8 12.98 12.24 13 12.91 6.12];
<br />time_min = [18 14 9 13 12 13 13 18 10 14 19 20 22 16 13 10 13 19 20 16 11 8 13 7 19 22 17 14 16 10 22 18 20 24 16 16 11 19 20 19 17 15 17 17 10 21 17 4 17 15 7 19 13 16 14 14 10 17 15 8 14 12 16 13 22 13 14 25 13 9 11 12 12 15 17 18 16 11 14 13 18 16 16 20 16 18 17 15 17 15 7 16 13 12 9 16 18 11 14 17 16 17 17 8];
<br />miles_end = [83 82 86 81 68 81 80 90 65 86 87 85 91 86 66 79 83 82 89 82 64 83 66 80 86 95 82 79 79 84 92 87 88 91 81 83 72 87 85 84 83 82 82 81 78 84 74 77 77 77 78 83 80 79 80 77 74 78 70 76 76 76 82 84 77 71 70 88 76 50 85 73 74 71 71 79 83 76 81 79 78 74 75 83 77 76 73 70 70 71 76 76 77 80 83 82 77 76 74 75 69 70 82 80];
<br /><br />global plot_enable dcfc_efficiency_pct dcfc_per_year battery_waranty_pct year_started;
<br />plot_enable = 1;
<br />dcfc_efficiency_pct = 94;
<br />dcfc_per_year = length(pct_start);
<br />battery_waranty_pct = 65;
<br />year_started = 1; % year data collection started; needed for battery extrapolate
<br /><br />idx0=35; idx_last=length(time_min);
<br />%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%<br />% DCFC changed from updating every second to every 10 seconds, and that also
<br />% seedm to have changed power characteristics. Only look at relevant group data.
<br />function analyze_data(idx0, idx1, ...
<br /> pct_start, miles_start, pct_end, charge_kwh, time_min, miles_end)
<br /> global plot_enable dcfc_efficiency_pct dcfc_per_year battery_waranty_pct year_started;
<br />
<br /> pct_start = pct_start (idx0:idx1);
<br /> miles_start = miles_start(idx0:idx1);
<br /> pct_end = pct_end (idx0:idx1);
<br /> charge_kwh = charge_kwh (idx0:idx1);
<br /> time_min = time_min (idx0:idx1);
<br /> miles_end = miles_end (idx0:idx1);
<br />
<br /> charge_pwr = charge_kwh ./ time_min * 60;
<br /> pct_charged = pct_end - pct_start;
<br /> miles_charged = miles_end - miles_start;
<br /> batt_kwh = charge_kwh ./ pct_charged * dcfc_efficiency_pct;
<br /> n=(1:length(batt_kwh))+idx0-1;
<br /><br /> % pct charged vs time in min; can we really get 80% in 20 minutes?
<br /> idx_less_than_80pct = (pct_end <= 85);
<br /> time_min_polyval = 0:30;
<br /> pct_charged_poly = polyfit(time_min(idx_less_than_80pct), ...
<br /> pct_charged(idx_less_than_80pct), 1);
<br /> pct_charged_polyval = polyval(pct_charged_poly, time_min_polyval);
<br /> charge_kwh_poly = polyfit(time_min(idx_less_than_80pct), ...
<br /> charge_kwh(idx_less_than_80pct), 1);
<br /> charge_kwh_polyval = polyval(charge_kwh_poly, time_min_polyval);
<br /> miles_charged_poly = polyfit(time_min(idx_less_than_80pct), ...
<br /> miles_charged(idx_less_than_80pct), 1);
<br /> miles_charged_polyval = polyval(miles_charged_poly, time_min_polyval);
<br />
<br /> if plot_enable == 1
<br /> figure;
<br /> plot(time_min, pct_charged, 'b.', ...
<br /> time_min_polyval, pct_charged_polyval, 'b-', ...
<br /> time_min, miles_charged, 'g.', ...
<br /> time_min_polyval, miles_charged_polyval, 'g-', ...
<br /> time_min, charge_kwh, 'r.', ...
<br /> time_min_polyval, charge_kwh_polyval, 'r-');
<br /> grid on;
<br /> title('raw %, miles, energy charged vs charge time, ending under 85% fit');
<br /> xlabel('charge time (min)'); ylabel('%, miles energy charged');
<br /> legend('% charged raw data', ...
<br /> [num2str(pct_charged_poly(1)) ' * minutes + ' ...
<br /> num2str(pct_charged_poly(2))],
<br /> 'miles charged raw data', ...
<br /> [num2str(miles_charged_poly(1)) ' * minutes + ' ...
<br /> num2str(miles_charged_poly(2))],
<br /> 'energy kwh charged raw data', ...
<br /> [num2str(charge_kwh_poly(1)) ' * minutes + ' ...
<br /> num2str(charge_kwh_poly(2))], ...
<br /> 'location', 'northwest');
<br /> endif
<br />
<br /> if plot_enable == 1
<br /> % charge power vs ending percent
<br /> figure; plot(pct_end, charge_pwr, 'b.', pct_charged, charge_pwr, 'r.');
<br /> grid on;
<br /> title('average charge power vs %');
<br /> xlabel('%'); ylabel('power (kW)');
<br /> legend('% end', '% charged', 'location', 'northwest');
<br />
<br /> % battery capacity over pct_charged; should not change much
<br /> figure; plot(pct_end, batt_kwh, 'b.', pct_charged, batt_kwh, 'r.');
<br /> grid on;
<br /> title('battery capacity vs %');
<br /> xlabel('%'); ylabel('battery capacity (kWh)');
<br /> legend('% end', '% charged', 'location', 'northwest');
<br /> endif
<br />
<br /> % battery capacity over time and curve fitting
<br /> % drop suspect data point, top 6 data points and bottom 1
<br /> batt_kwh_sorted = sort(batt_kwh, 'descend');
<br /> batt_kwh_top = batt_kwh_sorted(6);
<br /> batt_kwh_bottom = batt_kwh_sorted(length(batt_kwh_sorted));
<br /> idx_good_data = (batt_kwh < batt_kwh_top) & (batt_kwh > batt_kwh_bottom);
<br /> idx_bad_data = (batt_kwh >= batt_kwh_top) | (batt_kwh <= batt_kwh_bottom);
<br />
<br /> % charged kwh vs % charged after dropping suspect data points
<br /> charge_kwh_poly = polyfit(pct_charged(idx_good_data), ...
<br /> charge_kwh(idx_good_data), 1);
<br /> pct_charged_polyval = 0:100;
<br /> charge_kwh_polyval = polyval(charge_kwh_poly, pct_charged_polyval);
<br />
<br /> if plot_enable == 1
<br /> figure; plot(pct_charged, charge_kwh, 'b.', ...
<br /> pct_charged_polyval, charge_kwh_polyval, 'b-', ...
<br /> pct_charged_polyval, charge_kwh_polyval * dcfc_efficiency_pct / 100, 'r-', ...
<br /> pct_charged(idx_bad_data), charge_kwh(idx_bad_data), 'rx'); grid on;
<br /> title('charge energy vs charge percent');
<br /> xlabel('charged (%)'); ylabel('charged (kWh)');
<br /> legend('raw data', ...
<br /> [ 'dcfc: ' num2str(charge_kwh_poly(1)) ' * pct\_charged + ' ...
<br /> num2str(charge_kwh_poly(2))], ...
<br /> [ 'battery: ' num2str(charge_kwh_poly(1) * dcfc_efficiency_pct / 100) ...
<br /> ' * pct\_charged + ' ...
<br /> num2str(charge_kwh_poly(2) * dcfc_efficiency_pct / 100)], ...
<br /> 'discarded data', ...
<br /> 'location', 'northwest');
<br /> endif
<br /> % polyfit bad-data dropped battery data, linear and exponential
<br /> batt_poly = polyfit(n(idx_good_data), batt_kwh(idx_good_data), 1);
<br /> batt_polyval = polyval(batt_poly, n);
<br /> batt_poly_log = polyfit(n(idx_good_data), log(batt_kwh(idx_good_data)), 1);
<br /> batt_polyval_log = exp(polyval(batt_poly_log, n));
<br />
<br /> if plot_enable == 1
<br /> figure; plot(n, batt_kwh, 'b.', ...
<br /> n, batt_polyval, 'b-', n, batt_polyval_log, 'r-', ...
<br /> n(idx_bad_data), batt_kwh(idx_bad_data),'rx' );
<br /> grid on;
<br /> axis([idx0-1 idx1+1]);
<br /> title('battery capacity over time');
<br /> xlabel('sample (n)'); ylabel('battery capacity (kWh)');
<br /> legend('raw data', ...
<br /> [num2str(batt_poly(1)) ' * n + ' num2str(batt_poly(2))], ...
<br /> ['e\^(' num2str(batt_poly_log(1)) ' * n + ' ...
<br /> num2str(batt_poly_log(2)) ')'], ...
<br /> 'discarded data', ...
<br /> 'location', 'northeast');
<br /> endif
<br />
<br /> %extrapolate battery capacity in years, assuming X DCFC per year
<br /> years1 = year_started + n(idx_good_data)/dcfc_per_year;
<br /> batt_poly = polyfit(years1, batt_kwh(idx_good_data), 1);
<br /> batt_poly_log = polyfit(years1, log(batt_kwh(idx_good_data)), 1);
<br />
<br /> years = 0:0.25:15;
<br /> batt_polyval = polyval(batt_poly, years);
<br /> batt_polyval_log = exp(polyval(batt_poly_log, years));
<br />
<br /> % we know the initial capacity (t=0), and end of year 2 (last sample point).
<br /> % "stretch" the years as years_eq(uivalent) so that those two points are the
<br /> % same as linear fit.
<br /> years_eq = years .* (polyval(batt_poly, year_started+1) ./ batt_polyval);
<br /> batt_polyval_eq = polyval(batt_poly, years_eq);
<br /> batt_max = batt_poly(2) * ones(1, length(years));
<br />
<br /> if plot_enable == 1
<br /> figure; plot(years, batt_polyval, 'b-', ...
<br /> years, batt_polyval_log, 'g-', years, batt_polyval_eq, 'r-', ...
<br /> years, battery_waranty_pct / 100 * batt_max, 'c-', ...
<br /> years, 50 / 100 * batt_max, 'm-' ...
<br /> ); grid on;
<br /> title('battery capacity extrapolated over time');
<br /> xlabel('time (years)'); ylabel('battery capacity (kWh)');
<br /> legend(
<br /> [num2str(batt_poly(1)) ' * yr + ' num2str(batt_poly(2))], ...
<br /> ['e\^(' num2str(batt_poly_log(1)) ' * yr + ' ...
<br /> num2str(batt_poly_log(2)) ')'], ...
<br /> 'constant miles equivalent use', ...
<br /> [num2str(battery_waranty_pct) '% of peak'], ...
<br /> '50% of peak' ...
<br /> );
<br /> max_y_val = ((max(batt_polyval))/10) * 10;
<br /> axis([0 max(years) 0 max_y_val]);
<br /> set (gca, 'xtick', 0:max(years));
<br /> set (gca, 'ytick', (0:max_y_val/10:max_y_val));
<br /> endif
<br />
<br />endfunction
<br /><br />%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
<br />% check raw data
<br /><br />if plot_enable == 1
<br /> figure; plot(time_min, charge_kwh, '.'); grid on;
<br /> title('average charge energy vs charge time');
<br /> xlabel('time (min)'); ylabel('energy (kWh)');
<br />
<br /> charge_pwr = charge_kwh ./ time_min * 60;
<br /> figure; plot(charge_pwr, '.'); grid on;
<br /> title('average charge power vs time');
<br /> xlabel('sample (n)'); ylabel('power (kW)');
<br /><br /> %DCFC changed; cut the initial points that may not be valid; 2 separate analysis
<br /> figure;
<br /> subplot(2, 1, 1); plot(time_min(1:(idx0-1)), charge_kwh(1:(idx0-1)), '.');
<br /> grid on;
<br /> title(['average charge energy vs charge time, sample 1 to ' num2str(idx0-1)]);
<br /> xlabel('time (min)'); ylabel('energy (kWh)');
<br /> subplot(2, 1, 2); plot(time_min(idx0:idx_last), charge_kwh(idx0:idx_last), '.');
<br /> grid on;
<br /> title(['average charge energy vs charge time, sample ' ...
<br /> num2str(idx0) ' to end']);
<br /> xlabel('time (min)'); ylabel('energy (kWh)');
<br />
<br /> % which is correct? plot efficiency to find out.
<br /> miles = miles_end - miles_start;
<br /> mikwh = miles ./ charge_kwh;
<br /> mikwh_5_3 = ones(1,idx_last) * 5.3;
<br /> mikwh_mean0 = ones(1,idx_last) * mean(mikwh(1:(idx0-1)));
<br /> mikwh_mean1 = ones(1,idx_last) * mean(mikwh(idx0:idx_last));
<br /><br /> figure; plot(mikwh, 'b.', mikwh_5_3, 'g-', ...
<br /> mikwh_5_3 * dcfc_efficiency_pct / 100, 'r-', ...
<br /> mikwh_mean0, 'c-', mikwh_mean1, 'm-');
<br /> grid on;
<br /> title('efficiency over time');
<br /> xlabel('sample (n)'); ylabel('efficiency (mi/kWh)');
<br /> legend('raw data', '5.3 shown on dash', ...
<br /> [num2str(dcfc_efficiency_pct) '% of 5.3'], ...
<br /> ['1 to ' num2str(idx0-1) ' samples mean'], ...
<br /> [num2str(idx0) ' to end samples mean']);
<br />endif
<br />
<br />%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
<br />%analyze each data set independently
<br /><br />%analyze_data(1, idx0-1, ...
<br />% pct_start, miles_start, pct_end, charge_kwh, time_min, miles_end);
<br />%analyze_data(idx0, idx_last, ...
<br />% pct_start, miles_start, pct_end, charge_kwh, time_min, miles_end);
<br /><br />%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
<br />%fix samples 1 to 34 energy so that power looks like the rest
<br />charge_kwh_original = charge_kwh;
<br />charge_kwh(1:(idx0-1)) = charge_kwh(1:(idx0-1)) * 1.137; % via trial and error
<br />charge_pwr = charge_kwh ./ time_min * 60;
<br /><br />if plot_enable == 1
<br /> figure;
<br /> plot(charge_pwr, '.'); grid on;
<br /> title('average charge power vs time');
<br /> xlabel('sample (n)'); ylabel('power (kW)');
<br />endif
<br /><br />analyze_data(1, idx_last, ...
<br /> pct_start, miles_start, pct_end, charge_kwh, time_min, miles_end);
</span>sparkevhttp://www.blogger.com/profile/04362518920979349841noreply@blogger.com4tag:blogger.com,1999:blog-6875771813122616391.post-4766556829962581272017-02-10T18:01:00.000-08:002017-07-03T15:36:21.961-07:00SparkEV is the most efficient car in world historyIn previous blog post, I analyzed SparkEV acceleration performance. It was shown to have 0 to 60 MPH time of 7.2 seconds as claimed by Chevy, making it the quickest accelerating car in the world that cost under $20K.<br />
<br />
<a href="http://sparkev.blogspot.com/2016/06/sparkev-performance-analysis.html">http://sparkev.blogspot.com/2016/06/sparkev-performance-analysis.html</a><br />
<br />
One would think that such quick accelerating car would have awful efficiency. After all, conventional wisdom is that quick cars like Ferrari and Porsche get about 10 miles per gallon while one of the slowest accelerating cars on the road like Mitsubishi Mirage get about 40 miles per gallon. Even among small cars, the “powerful” Chevy SparkGas with about 100 HP gets about 35 miles per gallon while 70 HP Mirage gets 5 miles more per gallon.<br />
<br />
But upturning this conventional wisdom is SparkEV. I find that SparkEV as the quickest car in the world under $20K is also the most efficient car in history!<br />
<br />
<b>EPA says otherwise, buddy!</b><br />
<br />
One could search the Internet and see that older model BMW i3 with 22 kWh battery was rated by EPA as 124 MPGe while SparkEV was only rated for 119 MPGe (second place, tied with Bolt). However, the new BMW i3 with 33 kWh battery is only rated 118 MPGe, making it less efficient than SparkEV.<br />
<br />
<a href="http://insideevs.com/longer-range-2017-bmw-i3-33-kwh-battery-94-ah-arrived-us/">http://insideevs.com/longer-range-2017-bmw-i3-33-kwh-battery-94-ah-arrived-us/</a><br />
<br />
But we know better than to take EPA’s word for it. After all, EPA rated 2014 SparkEV range the same as 2015 that has smaller battery while Tony Williams range test showed that both 2014 and 2015 have greater range than EPA rating when driven at 62 MPH. Since 2014 has bigger battery, Tony’s test also showed more range for 2014 than 2015. EPA’s average test speed for MPGe determination is far less than 62 MPH, so Tony’s real-world test should’ve resulted in less range than EPA rating, which it clearly was not. You can’t trust the EPA numbers when it comes to real-world efficiency.<br />
<br />
In this blog post, I’ll explore why SparkEV is the most efficient production car in the world as well as in history.<br />
<br />
<b>Average efficiency over 16K miles</b><br />
<br />
To start off with, my 2015 SparkEV has about 16K miles on the odometer and average efficiency in almost 2 years is 5.3 mi/kWh. At 33.7 kWh/gal of gasoline, that’s equivalent to 179 MPGe! I haven’t reset the trip meter since getting the car, and below is a screen shot of current trip meter that shows average miles per kWh.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNW1nNQYD3AXQnpdw4luiBc2cDegzpjcbC85nnksJQgr5urN60kdgjrs7IrKTVYtP8jaAGnKGjkB9f_Nw76n_980GfDqSK6HXkGpEVtgYqEeAac398d3K2_9e-bBvVL9NQDoMdojWM1qek/s1600/mi_per_kwh_after_16kmiles.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNW1nNQYD3AXQnpdw4luiBc2cDegzpjcbC85nnksJQgr5urN60kdgjrs7IrKTVYtP8jaAGnKGjkB9f_Nw76n_980GfDqSK6HXkGpEVtgYqEeAac398d3K2_9e-bBvVL9NQDoMdojWM1qek/s1600/mi_per_kwh_after_16kmiles.gif" /></a></div>
<br />
<br />
Some forum posters claim they have over 6 mi/kWh after over 10K miles of driving. I would've said that's impossible nonsense that defy the laws of Physics if I didn't experience this for myself. SparkEV routinely get over 6 mi/kWh (202 MPGe) when driven in traffic clogged city.<br />
<br />
Some might claim that I’m a hypermiler, which isn’t true. I drive mostly in rural roads with average speed of about 45 MPH. Still, there’s the question of my driving being too conservative. A more standard test is to set the cruise control at some speed without wind and roughly similar elevation and record the efficiency.<br />
<br />
There are several such tests: one by Digital trends web site at 24 MPH, one recorded by Tony Williams at 62 MPH (100 kph), and another by me at 70 MPH. While 24 MPH and 62 MPH are oddball speeds, 70 MPH is something that is done regularly on the freeway, especially since roads with speed limit of 65 MPH have people driving at 70 MPH or more.<br />
<br />
<b>24 MPH efficiency</b><br />
<br />
24 MPH resulted in 7.2 mi/kWh with 2014 SparkEV. 7.2 mi/kWh is equivalent to 243 MPGe! Unfortunately, there aren’t test done at this speed with other cars to compare this number.<br />
<br />
<a href="http://www.digitaltrends.com/cars/spark-ev-world-record/">http://www.digitaltrends.com/cars/spark-ev-world-record/</a><br />
<br />
<b>62 MPH (100 kph) efficiency</b><br />
<br />
Tony Williams performed range tests for various EV at 62 MPH (100 kph). His test results can be found at the following link, and below that is the summary of results sorted in order of efficiency. As you can see, SparkEV clearly dominates in terms of efficiency in the real world driving at 62 MPH.<br />
<br />
<a href="http://www.mybmwi3.com/forum/viewtopic.php?t=2718">http://www.mybmwi3.com/forum/viewtopic.php?t=2718</a><br />
<br />
<table border="1">
<tbody>
<tr><td><b><b>pre 2017 </b>Car @ 62 MPH</b></td><td><b>mi/kWh</b></td><td><b>MPGe</b></td></tr>
<tr><td>SparkEV</td><td>5</td><td>168.5</td></tr>
<tr><td>BMW i3</td><td>4.7</td><td>158.4</td></tr>
<tr><td>BMW i3 Rex</td><td>4.6</td><td>155.0</td></tr>
<tr><td>VW eGolf</td><td>4.1</td><td>138.2</td></tr>
<tr><td>Nissan Leaf</td><td>4</td><td>134.8</td></tr>
<tr><td>Kia Soul EV</td><td>4</td><td>134.8</td></tr>
<tr><td>Rav4EV</td><td>3.4</td><td>114.6</td></tr>
</tbody></table>
<br />
But do I trust some third party test result? Considering Tony Williams runs the best EV after market product company in the world, I have high degree of confidence that he ran the tests properly.<br />
<br />
<b>Public service announcement</b><br />
<br />
As a side note for those with Rav4EV or Tesla Roadster who wish to use DCFC, you can contact Tony’s company for installing Jdemo which allows you to use Chademo DCFC. If you have other EV without DCFC, watch for his company to see if they’ll announce DCFC product for you. Your “toy car without DCFC” that could only muster about 30 miles from home could drive literally thousand miles in a day with DCFC, just like real cars.<br />
<br />
<a href="http://www.quickchargepower.com/">http://www.quickchargepower.com</a><br />
<br />
And no, I don’t get commission from Tony. I like endorsing great products, just like how I endorsed ev-vin’s lease blog. If you’re interested in leasing an EV, check out ev-vin’s blog.<br />
<br />
<a href="http://ev-vin.blogspot.com/">http://ev-vin.blogspot.com</a><br />
<br />
<b>70 MPH efficiency</b><br />
<br />
I drove at 70 MPH, and found the efficiency to be 4.4 mi/kWh (148 MPGe). The test conditions were:<br />
<br />
1. Charged using DCFC to 80%. It showed 73 miles remaining. Elevation at starting DCFC was 452 feet. There were two dogs and about 50 lbs of gear in the car plus the driver for a total of about 400 lb additional weight.<br />
<br />
2. After charging to 80%, drove about 1 mile to freeway at about 30 MPH average speed (couple of traffic lights, all green).<br />
<br />
3. Set the cruise control at 70 MPH in freeway. There wasn’t much traffic, which allowed this speed all the way, although there were few instances that I had to accelerate beyond 70 MPH for short time to pass slow semi-trucks.<br />
<br />
4. After driving about 52 miles in freeway, I pull off the freeway.<br />
<br />
5. Drove about 1 mile at average speed of about 40 MPH to DCFC. Elevation at ending DCFC was 698 feet, about 250 ft elevation gain.<br />
<br />
6. Upon arrival at DCFC, car reported 8 miles remaining, and DCFC reported 10% battery remaining. Most importantly, it reported 4.4 mi/kWh for 54.05 miles trip.<br />
<br />
Yes folks. SparkEV driven for 70% of its battery at 70 MPH AND going up 250 ft in elevation resulted in 4.4 mi/kWh (148 MPGe). Sure, it had about 2 miles of lower speed from/to DCFC, but that’s more than compensated with elevation gain and sporadic speed-up to pass slow trucks.<br />
<br />
But you might be wondering if that’s any good. After all, Bolt is rated the same EPA highway MPGe as SparkEV, and old BMW i3 was EPA rated even higher. Unlike 62 MPH test by Tony Williams, there is no one place that ran the tests at 70 MPH in the real world for various cars. Then we google some test results from various places and come up with some numbers. Below table shows the findings and the source of the numbers.<br />
<br />
<table border="1">
<tbody>
<tr><td><b>pre 2017 Car @ 70 MPH</b></td><td><b>mi/kWh</b></td><td><b>MPGe</b></td><td><b>data source </b></td></tr>
<tr><td>SparkEV</td><td>4.4</td><td>148.3</td><td>Me!</td></tr>
<tr><td>Chevy Bolt</td><td>4</td><td>134.8</td><td><a href="http://insideevs.com/chevrolet-bolt-volt-real-world-efficiency-comparison-video/">http://insideevs.com/chevrolet-bolt-volt-real-world-efficiency-comparison-video/</a></td></tr>
<tr><td>BMW i3</td><td>3.7</td><td>124.7</td><td><a href="http://www.greencarreports.com/news/1093160_2014-bmw-i3-what-a-tesla-driver-thinks-of-new-electric-bmw/page-2">http://www.greencarreports.com/news/1093160_2014-bmw-i3-what-a-tesla-driver-thinks-of-new-electric-bmw/page-2</a></td></tr>
<tr><td>Fiat 500e</td><td>3.6</td><td>121.3</td><td><a href="http://www.fiat500usaforum.com/archive/index.php/t-17944.html">http://www.fiat500usaforum.com/archive/index.php/t-17944.html</a></td></tr>
<tr><td>Tesla S 70D</td><td>3.429</td><td>115.6</td><td><a href="https://teslamotorsclub.com/tmc/threads/epa-range-for-70d-240-miles-does-it-make-sense.45570/#post-968034">https://teslamotorsclub.com/tmc/threads/epa-range-for-70d-240-miles-does-it-make-sense.45570/#post-968034</a></td></tr>
<tr><td>Nissan Leaf</td><td>2.92</td><td>98.4</td><td><a href="http://www.mynissanleaf.com/posting.php?mode=quote&f=31&p=301555&sid=e7bb77cf3f59809ed9f0ac9f27dcccbd">http://www.mynissanleaf.com/posting.php?mode=quote&f=31&p=301555&sid=e7bb77cf3f59809ed9f0ac9f27dcccbd</a></td></tr>
</tbody></table>
<br />
Clearly, SparkEV is the most efficient car in the world!<br />
<br />
<b>Other cars and speeds</b><br />
<br />
For Renault Zoe, which is not available in US, a forum post shows 55 MPH resulting in 4 mi/kWh.<br />
<br />
<a href="http://myrenaultzoe.com/index.php/topic/how-fast-how-far/#post-13351">http://myrenaultzoe.com/index.php/topic/how-fast-how-far/#post-13351</a><br />
<br />
SparkEV’s 4.4 mi/kWh at 70 MPH is even better than Zoe’s 4 mi/kWh at 55 MPH.<br />
<br />
For Mitsubishi iMiev, a forum post shows 65-70 MPH result in 39 miles to low battery light and 45 miles to “turtle mode”.<br />
<br />
<a href="https://www.edmunds.com/mitsubishi/i-miev/2012/long-term-road-test/mpg.html">https://www.edmunds.com/mitsubishi/i-miev/2012/long-term-road-test/mpg.html</a><br />
<br />
iMiev has 16 kWh battery. Assuming only 14 kWh out of 16 kWh battery was used, 39 miles would be 2.79 mi/kWh. Even if you assume 45 miles, that still only 3.21 mi/kWh. (if you assume more battery used, that result in worse mi/kWh) Either way, they’re all worse than SparkEV’s 4.4 mi/kWh at constant 70 MPH.<br />
<br />
<b>Some caveats</b><br />
<br />
How trustworthy are these number from various forum posts? I leave it up to the reader to do deeper research. But from what I found, SparkEV is clearly the most efficient car in the world. Because EV are far more efficient than cars using any other form of energy, and modern EV came on the scene just few years ago, SparkEV is the most efficient car in history!<br />
<br />
Above discussion on efficiency was energy efficiency from battery-to-wheels point of view and assuming 33.7 kWh per gallon of gas in computing MPGe. It did not take into account charging loss. Charging efficiency using 120V is about 80%, 240V is about 85%, DCFC is about 94%. Since the 70 MPH test was done only using DCFC, we can analyze the actual energy from outlet-to-wheels rather than battery-to-wheels.<br />
<br />
At destination DCFC in my 70 MPH test, SparkEV at 10% took 17 minutes 30 seconds and 13.07 kWh to get back to 80%. That is average power of 13.07/(17.5/60) = 44.8 kW. You might be wondering why it’s so low since SparkEV is capable of 48 kW to 80%, making it the world’s quickest charging EV.<br />
<br />
<a href="http://sparkev.blogspot.com/2015/12/sparkev-is-quickest-charging-ev-in-world.html">http://sparkev.blogspot.com/2015/12/sparkev-is-quickest-charging-ev-in-world.html</a><br />
<br />
Higher voltage as the battery is filled result in higher power if the current is the same (power = voltage times current). SparkEV pulls roughly the same current to 80%, so the peak power is higher while the average power would be less. In any case, close to 45 kW to 80% isn’t bad. Moving on.<br />
<br />
54.05 miles taking 13.07 kWh is 4.14 mi/kWh.<br />
<br />
The charging efficiency for the trip is 4.14 / 4.4 = 94%<br />
<br />
To calculate outlet-to-wheels MPGe, one has to take 94% of battery-to-wheels figure. Even if we assume all other cars in 70 MPH test were from wall to wheels, which isn’t the case, none of them is more than 4 mi/kWh, a figure SparkEV easily beats with 4.14 mi/kWh.<br />
<br />
Some gasbags might argue that electricity distribution is only 90% efficient and generation is only 30% efficient. While technically true in some rare instances (ie, peaker gas turbine generators), gas cars only consider efficiency from what’s in the gas tank, not what energy was used to explore, drill, ship, refine, military to invade / protect countries with oil etc. Rather than analyzing all the complex scenarios, we simply analyze what comes out from the energy stored in the car (battery to wheels).<br />
<br />
<b>What will beat SparkEV in efficiency?</b><br />
<br />
The question that comes to mind is when will there be a car that is more efficient than SparkEV? Unfortunately, it doesn’t seem likely that will happen any time soon.<br />
<br />
First is the question of weight. SparkEV is only 2866 lb while Leaf, Bolt, etc. are close to 3500 lb. Even the BMW i3 that uses carbon fiber to reduce the weight now has larger battery and weighs similar to SparkEV while Tesla S weighs close to 4000 lb. From rolling resistance point of view, SparkEV with small eco-tires will probably remain the most efficient EV in the world.<br />
<br />
Second is the question of aerodynamics. While SparkEV has pretty awful drag coefficient at 0.324, it has very small frontal area. Combined, they contribute to small overall aerodynamic drag. While I haven’t investigated this further, the test result at 70 MPH shows that SparkEV performs quite well at highway speeds.<br />
<br />
Third is the question of drive train efficiency. SparkEV is unique among EV in the gear ratio. All the other EV hover around 9 to 1 ratio (9 motor turns for 1 wheel turn). Even the Chevy Bolt hover around 7 to 1 ratio. SparkEV by comparison is about 3.17 to 1 ratio (2015+ has 3.71 to 1 ratio). That means the motor is turning less than half the speed of other EV for given road speed. While the motor efficiency is a complicated subject, slower turning tend to be more efficient when all other factors being equal since moving parts don’t have to drag around as much “fluid” (aka, air, lubricants, bearing friction).<br />
<br />
A potential candidate that could beat SparkEV is Tesla model 3. Tesla 3 is supposed to have drag coefficient of about 0.21, but it’s also larger frontal area as well as heavier. It also has Tesla drive train that is much more powerful, which may not be as efficient as less powerful SparkEV drive train. Judging from Bolt that is more efficient than much less powerful Leaf, it seems GM engineers make the most efficient drive train even with more power. It is unlikely Tesla 3 will beat SparkEV in efficiency.<br />
<br />
Another candidate is Hyundai Ioniq electric version (not the hybrid/plug-in hybrid). Supposedly, that has the best EPA MPGe rating among any car at 136 MPGe and much less powerful motor than SparkEV. But I discussed EPA’s problem earlier in this blog post. Until someone performs a real world test when (if?) the car becomes available, we won’t know if it’ll be more efficient than SparkEV. I suspect SparkEV will be more efficient, just because I am thoroughly impressed with Chevy engineering.<br />
<br />
So for the foreseeable future (until SparkEV 2.0?), SparkEV will reign supreme as the most efficient car in history.<br />
<br />
<b>Profile of history’s most efficient car</b><br />
<br />
From the test results, it seems the 2015 SparkEV has the same efficiency curve of 2014 that I deduced in earlier blog post.<br />
<br />
<a href="http://sparkev.blogspot.com/2016/03/range-polynomial.html">http://sparkev.blogspot.com/2016/03/range-polynomial.html</a><br />
<br />
Below may be what the miles per kWh (or MPGe) profile of history’s most efficient car looks like. I challenge the world to beat that.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjQVrEhyphenhyphenRJ10KFAdja9xnuGm29uSreAv7umKJyflKk6R2ZwiqzmFpU0zwuhHvjzZd2JhqztAgVZM55_1VN28K3TlxhWRWw_8OTpXA8J945PX2TFu1pLEf_2XVj1G9MXngPDgebylZzUOlnZ/s1600/2014_mikwh_over_power.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjQVrEhyphenhyphenRJ10KFAdja9xnuGm29uSreAv7umKJyflKk6R2ZwiqzmFpU0zwuhHvjzZd2JhqztAgVZM55_1VN28K3TlxhWRWw_8OTpXA8J945PX2TFu1pLEf_2XVj1G9MXngPDgebylZzUOlnZ/s1600/2014_mikwh_over_power.gif" /></a></div>
<br />
<b>Edit: 2017-06-28</b><br />
<br />
Normally, I don’t pay attention to car’s efficiency. But going for a long drive (125 miles each way) and traffic slower than the speed limit, I got bored and started doing mi/kWh math in my head. The car shows MPH and kW of power being used, it’s simple matter of division to figure out mi/kWh (I think this is called mental masturbation, but I digress). I was mostly getting over 6 mi/kWh and often 8 or 9 mi/kWh! I was often under the speed limit but still about 45 MPH on average, not crawling at 20 MPH.<br />
<br />
When I got to the DCFC station about 80 miles away after about 1 hour 45 minutes of driving (1.75 hours), the car reported 6.4 mi/kWh (216 MPGe battery to wheels)! Average speed was 79/1.75 = 45 MPH. The elevation change was about 100 ft down from the starting point, but that has little effect. Basically, if one’s in light traffic, achieving such phenomenal efficiency with SparkEV can be expected. Below is the screen shot.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgId2pSRO6-r4pVwXWMrdJ20RTePi6_Nfw44IYf1EBfT26fkW4EDBRmKmbnKHWR8ZRkhV04lBIgPDPMl2y0Wjxs7LQP817wR37Dp4wvOEDutIQZF5sTgQgrYGs9vTWCrE-AlNajzVCGQRDn/s1600/efficiency_6.4mi_kwh.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="240" data-original-width="380" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgId2pSRO6-r4pVwXWMrdJ20RTePi6_Nfw44IYf1EBfT26fkW4EDBRmKmbnKHWR8ZRkhV04lBIgPDPMl2y0Wjxs7LQP817wR37Dp4wvOEDutIQZF5sTgQgrYGs9vTWCrE-AlNajzVCGQRDn/s1600/efficiency_6.4mi_kwh.gif" /></a></div>
<br />
The energy used in this drive was 79/6.4 = 12.34 kWh.<br />
<br />
Then on the way back, I was curious if I can achieve the same efficiency. Unfortunately, the starting DCFC was not the same as the ending DCFC location from previous drive. In addition, the traffic was moving quite well. There were some sections of stop-and-go, and other sections where the speed was over 65 MPH, but I generally kept the cruise control set to 60 MPH. I drove 65 miles taking 1 hour 15 minutes, average speed of 52 MPH. The efficiency showed 5.4 mi/kWh (182 MPGe battery to wheels)!<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNvgSiVUj2QX_zrctHpkLKVl6-1QvOLgp3c9dTfUl2OwoVVmx_HUxilwJ86kRAWLErCkhzdsuyabjbBUlOApRIpZnx37-0GuTZW5w93-jhZNALvFiRSAmL1oAbmBvpQ5HO3hx45ITsmd5Q/s1600/efficiency_5.4mi_kwh.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="240" data-original-width="380" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNvgSiVUj2QX_zrctHpkLKVl6-1QvOLgp3c9dTfUl2OwoVVmx_HUxilwJ86kRAWLErCkhzdsuyabjbBUlOApRIpZnx37-0GuTZW5w93-jhZNALvFiRSAmL1oAbmBvpQ5HO3hx45ITsmd5Q/s1600/efficiency_5.4mi_kwh.gif" /></a></div>
<br />
The energy used in this drive was 65/5.4 = 12.04 kWh<br />
<br />
Then the total distance for recorded section of the trip was 79+65=144 miles taking 12.34+12.04=24.38 kWh. That results in average efficiency of 5.9 mi/kWh (199 MPGe battery to wheels)!<br />
<br />
At $0.20/kWh in San Diego electric prices, 24.4 kWh is $4.88. Gas prices are about $2.75/gal, so the cost to drive 144 miles is about 1.77 gallons of gas, or 81 miles per gallon equivalent in terms of money out of pocket (MPGe$).<br />
<br />
That’s the real-deal: SparkEV costs less to drive than any gas car, probably less than any EV, while being the quickest car in the world that cost under $20K when new. Now THAT is an engineering marvel.sparkevhttp://www.blogger.com/profile/04362518920979349841noreply@blogger.com10tag:blogger.com,1999:blog-6875771813122616391.post-89828360728705695792016-06-30T15:47:00.002-07:002017-02-06T08:25:01.198-08:00SparkEV performance analysisYou get excited about a car's performance, and the most bold statement a car can make is acceleration, especially 0 to 60 MPH time. Indeed, we get excited about Tesla P90DL time of 2.9 seconds and even Veryon's 2.4 seconds, yet we hardly notice cars like Mitsubishi Mirage for getting 44 MPG as a gas engine car (not hybrid) with 0-60 MPH time close to 14 seconds.<br />
<br />
That's what makes SparkEV so exciting: it is the quickest car under $20K in 0-60 MPH at 7.2 seconds while achieving 119 MPGe (EPA) or equivalent to a gas car that gets over 64 MPGe$ when gas is $2.5/gal and electricity at $0.17/kWh (efficiency at 4.4 mi/kWh wall to battery). There is no car that achieves this level of performance and efficiency for such low price.<br />
<br />
But does SparkEV really get 0-60 MPH time of 7.2 seconds? In my informal testing, time is always less than 7 seconds, though I'm probably biased. Some claim that the time is exaggerated, and the actual time is closer to 8 seconds, but it's hard to know if they used correct conditions. To test the peak performance of any EV, the battery must be new, fully charged and cool, tires warm enough to hold traction, and many other factors. It might seem silly to talk about traction on 7.2 sec car, but if you drive SparkEV, you know that the traction control regularly kicks in when you stomp on the accelerator, especially on even slightly bumpy road. There is also the question of driver's reaction time as well as roll out uncertainty.<br />
<br />
In this blog post, I'll do what I did with "can stock Corvette beat Tesla P90DL in 0-60 MPH" and "range polynomial" blog posts : make a model of car's acceleration from power/torque curves. Then the acceleration curve can be applied without regard to such things as driver reaction time. As before, one should heed this giant caveat.<br />
<br />
<div style="text-align: center;">
<span style="font-size: x-large;">THESE ARE MADE UP NUMBERS, AND THEY SHOULD NOT BE TRUSTED!</span></div>
<br />
I will give explanations on how these plots are obtained as well as the source code. One is free to examine them and decide how valid these plots may be. Since the numbers come out roughly what's found through various other experiments, these are probably close to reality.<br />
<b><br /></b>
<b>Experimental data</b><br />
<br />
There are many experimental data on 2014 SparkEV, but none available for 2015/2016 other than Chevy's web site. While all years of SparkEV have the same power and rear wheel torque, 2014 had 21 kWh of A123 battery and it's heavier by about 100 lb compared to later years. As such, 2015/2016 would have better performance characteristics. Because we are making a model of performance, we have to start with 2014 and check/tweak our model until it matches the experimental data. Once that's done, same process can be applied to later years.<br />
<br />
We have the following experimental data for 2014 SparkEV.<br />
<br />
Chevy web site (no longer available)<br />
0-60 MPH: 7.5 seconds<br />
<br />
<a href="http://www.motortrend.com/news/2014-chevrolet-spark-ev-2lt-first-test">http://www.motortrend.com/news/2014-chevrolet-spark-ev-2lt-first-test</a><br />
0-60 MPH: 7.5 seconds<br />
1/4 mile: 16 sec at 87.6 MPH.<br />
<br />
<a href="http://insideevs.com/plug-vehicle-cross-section-acceleration-30-mph-60-mph-ev-mode">http://insideevs.com/plug-vehicle-cross-section-acceleration-30-mph-60-mph-ev-mode</a><br />
0-30 MPH: 3.2 seconds (car and driver)<br />
0-60 MPH: 7.9 seconds (car and driver)<br />
<br />
<a href="http://mychevysparkev.com/forum/viewtopic.php?f=9&t=3563">http://mychevysparkev.com/forum/viewtopic.php?f=9&t=3563</a><br />
0-60 MPH: 7.5 (best run)<br />
1/4 mile: 15.8 seconds @ 86.12 mph<br />
<br />
<a href="http://insideevs.com/whats-the-difference-0-30-mph-chevrolet-spark-ev-vs-nissan-leaf-videos">http://insideevs.com/whats-the-difference-0-30-mph-chevrolet-spark-ev-vs-nissan-leaf-videos</a><br />
0-30 MPH: 3.1 sec<br />
0-60 MPH: 8 sec<br />
<br />
In summary, following can be expected.<br />
0-30 MPH: bit over 3 seconds<br />
0-60 MPH: bit over 7.5 seconds<br />
1/4 mile: under 16 seconds at about 86 MPH<br />
<br />
<b>2014 SparkEV</b><br />
<br />
Since I don't know the test conditions, I plot several scenarios:<br />
<br />
1. 2014 with drag and 150 lb driver<br />
2. 2014 with drag but no driver<br />
3. 2014 with drag and 75 lb driver (dog driving?)<br />
4. 2014 without drag and 150 lb driver<br />
<br />
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<table border="1">
<tbody>
<tr bgcolor="#C0C0C0"><td width="64">speed (mph)</td><td width="64">2014 time (sec)</td><td width="64">2014 gforce</td><td width="64">2014 no driver time (sec)</td><td width="64">2014 no driver gforce</td><td width="64">2014 75lb driver time (sec)</td><td width="64">2014 75lb driver gforce</td><td width="64">2014 no drag time (sec)</td><td width="64">2014 no drag gforce</td></tr>
<tr><td width="64">0</td><td width="64">0.00</td><td width="64">0.39</td><td width="64">0.00</td><td width="64">0.41</td><td width="64">0.00</td><td width="64">0.40</td><td width="64">0.00</td><td width="64">0.39</td></tr>
<tr><td width="64">5</td><td width="64">0.56</td><td width="64">0.41</td><td width="64">0.53</td><td width="64">0.43</td><td width="64">0.55</td><td width="64">0.42</td><td width="64">0.56</td><td width="64">0.41</td></tr>
<tr><td width="64">10</td><td width="64">1.12</td><td width="64">0.41</td><td width="64">1.06</td><td width="64">0.43</td><td width="64">1.09</td><td width="64">0.42</td><td width="64">1.12</td><td width="64">0.41</td></tr>
<tr><td width="64">15</td><td width="64">1.68</td><td width="64">0.41</td><td width="64">1.59</td><td width="64">0.43</td><td width="64">1.63</td><td width="64">0.42</td><td width="64">1.67</td><td width="64">0.41</td></tr>
<tr><td width="64">20</td><td width="64">2.24</td><td width="64">0.41</td><td width="64">2.13</td><td width="64">0.43</td><td width="64">2.18</td><td width="64">0.42</td><td width="64">2.23</td><td width="64">0.41</td></tr>
<tr><td width="64">25</td><td width="64">2.80</td><td width="64">0.40</td><td width="64">2.66</td><td width="64">0.43</td><td width="64">2.73</td><td width="64">0.42</td><td width="64">2.79</td><td width="64">0.41</td></tr>
<tr><td width="64">30</td><td width="64">3.36</td><td width="64">0.40</td><td width="64">3.20</td><td width="64">0.43</td><td width="64">3.28</td><td width="64">0.41</td><td width="64">3.34</td><td width="64">0.41</td></tr>
<tr><td width="64">35</td><td width="64">3.93</td><td width="64">0.40</td><td width="64">3.74</td><td width="64">0.42</td><td width="64">3.83</td><td width="64">0.41</td><td width="64">3.90</td><td width="64">0.40</td></tr>
<tr><td width="64">40</td><td width="64">4.52</td><td width="64">0.38</td><td width="64">4.30</td><td width="64">0.40</td><td width="64">4.41</td><td width="64">0.39</td><td width="64">4.48</td><td width="64">0.39</td></tr>
<tr><td width="64">45</td><td width="64">5.15</td><td width="64">0.35</td><td width="64">4.90</td><td width="64">0.37</td><td width="64">5.02</td><td width="64">0.36</td><td width="64">5.08</td><td width="64">0.36</td></tr>
<tr><td width="64">50</td><td width="64">5.86</td><td width="64">0.30</td><td width="64">5.58</td><td width="64">0.31</td><td width="64">5.72</td><td width="64">0.31</td><td width="64">5.76</td><td width="64">0.32</td></tr>
<tr><td width="64">55</td><td width="64">6.70</td><td width="64">0.26</td><td width="64">6.37</td><td width="64">0.27</td><td width="64">6.54</td><td width="64">0.26</td><td width="64">6.54</td><td width="64">0.28</td></tr>
<tr><td width="64">60</td><td width="64">7.67</td><td width="64">0.22</td><td width="64">7.29</td><td width="64">0.23</td><td width="64">7.48</td><td width="64">0.23</td><td width="64">7.42</td><td width="64">0.25</td></tr>
<tr><td width="64">65</td><td width="64">8.79</td><td width="64">0.19</td><td width="64">8.36</td><td width="64">0.20</td><td width="64">8.57</td><td width="64">0.20</td><td width="64">8.40</td><td width="64">0.22</td></tr>
<tr><td width="64">70</td><td width="64">10.08</td><td width="64">0.17</td><td width="64">9.58</td><td width="64">0.18</td><td width="64">9.83</td><td width="64">0.17</td><td width="64">9.49</td><td width="64">0.20</td></tr>
<tr><td width="64">75</td><td width="64">11.58</td><td width="64">0.14</td><td width="64">11.00</td><td width="64">0.15</td><td width="64">11.29</td><td width="64">0.15</td><td width="64">10.68</td><td width="64">0.18</td></tr>
<tr><td width="64">80</td><td width="64">13.30</td><td width="64">0.13</td><td width="64">12.64</td><td width="64">0.13</td><td width="64">12.97</td><td width="64">0.13</td><td width="64">11.98</td><td width="64">0.17</td></tr>
<tr><td width="64">85</td><td width="64">15.30</td><td width="64">0.11</td><td width="64">14.53</td><td width="64">0.11</td><td width="64">14.91</td><td width="64">0.11</td><td width="64">13.37</td><td width="64">0.16</td></tr>
<tr><td width="64">90</td><td width="64">18.09</td><td width="64">0.06</td><td width="64">17.18</td><td width="64">0.07</td><td width="64">17.64</td><td width="64">0.07</td><td width="64">15.01</td><td width="64">0.12</td></tr>
</tbody></table>
<br />
The times range from 7.29 seconds without driver (#2) to 7.67 seconds with 150 lb driver (#1). Assuming 75 lb driver is 7.48 seconds, closer to Chevy's claim. But I think it's against the law in most places to have your dog drive the car!<br />
<br />
Kidding aside, the model is roughly in line with experimental data, though realistic case of driver + drag is about 0.17 seconds slower. Indeed, Mark from insideevs measured 3.1 seconds to 30 MPH using SparkEV with 1.5 year old and 16K miles worn battery, and the model shows 0.26 seconds slower at 3.36 seconds to 30 MPH. As you read forward, keep in mind that actual could be 0.17 to 0.26 seconds quicker than the graphs / tables shown in this blog post.<br />
<br />
Note the g-force that's slightly above 0.4g until about 35 MPH and the gradual decrease. While this is pitiful compared to motorcycles and Tesla P90DL, contrast that to Nissan Leaf that pull maximum g only up to about 25 MPH then takes 7 seconds to accelerate from 30 MPH to 60 MPH, and you can see why SparkEV is such an acceleration beast.<br />
<br />
I think this validates the model methodology as "close enough". Let's move on to 2015.<br />
<br />
<b>2015 SparkEV</b><br />
<br />
2015 is about 100 lb lighter than 2014 while having the same horsepower rating. Motor torque is less, but that is compensated with lower gearing to have the same torque at the wheels, and one would expect quicker times. Since one would typically carry "stuff" and make it heavier, I plot from 0 lb to 700 lb added weights in 100 lb increments (always assume 150 lb for driver as a given). 700 lb extra (which is 850 lb including the driver) is roughly the gross vehicle weight rating (GVWR) of the car, the maximum rated weight.<br />
<br />
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<table border="1">
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<tr bgcolor="#C0C0C0"><td width="64">speed (mph)</td><td width="64">3016lb time (sec)</td><td width="64">3016lb gforce</td><td width="64">3116lb time (sec)</td><td width="64">3116lb gforce</td><td width="64">3216lb time (sec)</td><td width="64">3216lb gforce</td><td width="64">3316lb time (sec)</td><td width="64">3316lb gforce</td><td width="64">3416lb time (sec)</td><td width="64">3416lb gforce</td><td width="64">3516lb time (sec)</td><td width="64">3516lb gforce</td><td width="64">3616lb time (sec)</td><td width="64">3616lb gforce</td><td width="64">3716lb time (sec)</td><td width="64">3716lb gforce
</td></tr>
<tr><td width="64">0</td><td width="64">0.00</td><td width="64">0.40</td><td width="64">0.00</td><td width="64">0.39</td><td width="64">0.00</td><td width="64">0.38</td><td width="64">0.00</td><td width="64">0.37</td><td width="64">0.00</td><td width="64">0.36</td><td width="64">0.00</td><td width="64">0.35</td><td width="64">0.00</td><td width="64">0.34</td><td width="64">0.00</td><td width="64">0.33</td></tr>
<tr><td width="64">5</td><td width="64">0.54</td><td width="64">0.43</td><td width="64">0.56</td><td width="64">0.41</td><td width="64">0.57</td><td width="64">0.40</td><td width="64">0.59</td><td width="64">0.39</td><td width="64">0.61</td><td width="64">0.38</td><td width="64">0.63</td><td width="64">0.36</td><td width="64">0.65</td><td width="64">0.35</td><td width="64">0.67</td><td width="64">0.34</td></tr>
<tr><td width="64">10</td><td width="64">1.07</td><td width="64">0.43</td><td width="64">1.11</td><td width="64">0.41</td><td width="64">1.15</td><td width="64">0.40</td><td width="64">1.18</td><td width="64">0.39</td><td width="64">1.22</td><td width="64">0.37</td><td width="64">1.26</td><td width="64">0.36</td><td width="64">1.29</td><td width="64">0.35</td><td width="64">1.33</td><td width="64">0.34</td></tr>
<tr><td width="64">15</td><td width="64">1.61</td><td width="64">0.42</td><td width="64">1.66</td><td width="64">0.41</td><td width="64">1.72</td><td width="64">0.40</td><td width="64">1.77</td><td width="64">0.39</td><td width="64">1.83</td><td width="64">0.37</td><td width="64">1.88</td><td width="64">0.36</td><td width="64">1.94</td><td width="64">0.35</td><td width="64">1.99</td><td width="64">0.34</td></tr>
<tr><td width="64">20</td><td width="64">2.15</td><td width="64">0.42</td><td width="64">2.22</td><td width="64">0.41</td><td width="64">2.29</td><td width="64">0.40</td><td width="64">2.36</td><td width="64">0.38</td><td width="64">2.44</td><td width="64">0.37</td><td width="64">2.51</td><td width="64">0.36</td><td width="64">2.58</td><td width="64">0.35</td><td width="64">2.66</td><td width="64">0.34</td></tr>
<tr><td width="64">25</td><td width="64">2.68</td><td width="64">0.42</td><td width="64">2.78</td><td width="64">0.41</td><td width="64">2.87</td><td width="64">0.39</td><td width="64">2.96</td><td width="64">0.38</td><td width="64">3.05</td><td width="64">0.37</td><td width="64">3.14</td><td width="64">0.36</td><td width="64">3.23</td><td width="64">0.35</td><td width="64">3.33</td><td width="64">0.34</td></tr>
<tr><td width="64">30</td><td width="64">3.23</td><td width="64">0.42</td><td width="64">3.33</td><td width="64">0.41</td><td width="64">3.44</td><td width="64">0.39</td><td width="64">3.55</td><td width="64">0.38</td><td width="64">3.66</td><td width="64">0.37</td><td width="64">3.77</td><td width="64">0.36</td><td width="64">3.89</td><td width="64">0.35</td><td width="64">4.00</td><td width="64">0.34</td></tr>
<tr><td width="64">35</td><td width="64">3.77</td><td width="64">0.41</td><td width="64">3.90</td><td width="64">0.40</td><td width="64">4.03</td><td width="64">0.39</td><td width="64">4.16</td><td width="64">0.37</td><td width="64">4.29</td><td width="64">0.36</td><td width="64">4.42</td><td width="64">0.35</td><td width="64">4.54</td><td width="64">0.34</td><td width="64">4.67</td><td width="64">0.33</td></tr>
<tr><td width="64">40</td><td width="64">4.34</td><td width="64">0.40</td><td width="64">4.49</td><td width="64">0.38</td><td width="64">4.63</td><td width="64">0.37</td><td width="64">4.78</td><td width="64">0.36</td><td width="64">4.93</td><td width="64">0.35</td><td width="64">5.08</td><td width="64">0.34</td><td width="64">5.23</td><td width="64">0.33</td><td width="64">5.38</td><td width="64">0.32</td></tr>
<tr><td width="64">45</td><td width="64">4.94</td><td width="64">0.36</td><td width="64">5.11</td><td width="64">0.35</td><td width="64">5.28</td><td width="64">0.34</td><td width="64">5.45</td><td width="64">0.33</td><td width="64">5.62</td><td width="64">0.32</td><td width="64">5.79</td><td width="64">0.31</td><td width="64">5.95</td><td width="64">0.30</td><td width="64">6.12</td><td width="64">0.29</td></tr>
<tr><td width="64">50</td><td width="64">5.63</td><td width="64">0.31</td><td width="64">5.82</td><td width="64">0.30</td><td width="64">6.01</td><td width="64">0.29</td><td width="64">6.20</td><td width="64">0.28</td><td width="64">6.40</td><td width="64">0.27</td><td width="64">6.59</td><td width="64">0.27</td><td width="64">6.78</td><td width="64">0.26</td><td width="64">6.98</td><td width="64">0.25</td></tr>
<tr><td width="64">55</td><td width="64">6.43</td><td width="64">0.27</td><td width="64">6.65</td><td width="64">0.26</td><td width="64">6.87</td><td width="64">0.25</td><td width="64">7.09</td><td width="64">0.24</td><td width="64">7.31</td><td width="64">0.24</td><td width="64">7.53</td><td width="64">0.23</td><td width="64">7.75</td><td width="64">0.22</td><td width="64">7.97</td><td width="64">0.22</td></tr>
<tr><td width="64">60</td><td width="64">7.36</td><td width="64">0.23</td><td width="64">7.61</td><td width="64">0.22</td><td width="64">7.86</td><td width="64">0.22</td><td width="64">8.12</td><td width="64">0.21</td><td width="64">8.37</td><td width="64">0.20</td><td width="64">8.62</td><td width="64">0.20</td><td width="64">8.88</td><td width="64">0.19</td><td width="64">9.13</td><td width="64">0.19</td></tr>
<tr><td width="64">65</td><td width="64">8.43</td><td width="64">0.20</td><td width="64">8.72</td><td width="64">0.19</td><td width="64">9.01</td><td width="64">0.19</td><td width="64">9.30</td><td width="64">0.18</td><td width="64">9.59</td><td width="64">0.18</td><td width="64">9.88</td><td width="64">0.17</td><td width="64">10.17</td><td width="64">0.17</td><td width="64">10.46</td><td width="64">0.16</td></tr>
<tr><td width="64">70</td><td width="64">9.67</td><td width="64">0.17</td><td width="64">10.00</td><td width="64">0.17</td><td width="64">10.34</td><td width="64">0.16</td><td width="64">10.67</td><td width="64">0.16</td><td width="64">11.00</td><td width="64">0.15</td><td width="64">11.34</td><td width="64">0.15</td><td width="64">11.67</td><td width="64">0.14</td><td width="64">12.01</td><td width="64">0.14</td></tr>
<tr><td width="64">75</td><td width="64">11.11</td><td width="64">0.15</td><td width="64">11.49</td><td width="64">0.15</td><td width="64">11.87</td><td width="64">0.14</td><td width="64">12.26</td><td width="64">0.14</td><td width="64">12.64</td><td width="64">0.13</td><td width="64">13.03</td><td width="64">0.13</td><td width="64">13.41</td><td width="64">0.12</td><td width="64">13.80</td><td width="64">0.12</td></tr>
<tr><td width="64">80</td><td width="64">12.76</td><td width="64">0.13</td><td width="64">13.20</td><td width="64">0.13</td><td width="64">13.64</td><td width="64">0.12</td><td width="64">14.09</td><td width="64">0.12</td><td width="64">14.53</td><td width="64">0.11</td><td width="64">14.98</td><td width="64">0.11</td><td width="64">15.43</td><td width="64">0.11</td><td width="64">15.87</td><td width="64">0.10</td></tr>
<tr><td width="64">85</td><td width="64">14.67</td><td width="64">0.11</td><td width="64">15.18</td><td width="64">0.11</td><td width="64">15.69</td><td width="64">0.10</td><td width="64">16.20</td><td width="64">0.10</td><td width="64">16.72</td><td width="64">0.10</td><td width="64">17.24</td><td width="64">0.09</td><td width="64">17.75</td><td width="64">0.09</td><td width="64">18.27</td><td width="64">0.09</td></tr>
<tr><td width="64">90</td><td width="64">17.34</td><td width="64">0.07</td><td width="64">17.95</td><td width="64">0.06</td><td width="64">18.57</td><td width="64">0.06</td><td width="64">19.18</td><td width="64">0.06</td><td width="64">19.80</td><td width="64">0.06</td><td width="64">20.42</td><td width="64">0.06</td><td width="64">21.04</td><td width="64">0.05</td><td width="64">21.66</td><td width="64">0.05</td></tr>
</tbody></table>
<br />
Chevy advertises 7.2 seconds in 0-60 MPH, but no one seem to have actual drag strip data for 2015, so we don't have any basis for comparison other than Chevy's claim. The data shows that 0 lb added (but with 150 lb rider) is 7.36 seconds. Going by 0.17 second discrepancy, I suspect it'd be closer to 7.2 seconds in actual test. Then the range of acceleration through all possible additional weight is between 7.2 seconds and 9.2 seconds.<br />
<br />
An interesting observation here is that SparkEV fully loaded with 700 lb (850 lb with driver) at 9.2 seconds would be quicker than Leaf and eGolf without any addtional load to 60 MPH (both around 10 seconds). In fact, fully loaded SparkEV is probably quicker than even unladen Toyota Mirai fuel cell car that cost $60K. That's very impressive for a car that costs $16K in CA ($18K outside of CA).<br />
<br />
Next, the question is, what happens when you start to shed weight? There was a guy who removed body parts from Nissan Leaf to make it lighter by about 1000 lb. End result was weight to power ratio of about SparkEV.<br />
<div>
<br /></div>
<div>
<a href="http://insideevs.com/stripped-nissan-leaf-vw-bus-conversion-model-s-speed">http://insideevs.com/stripped-nissan-leaf-vw-bus-conversion-model-s-speed</a></div>
<div>
<br /></div>
<div>
<div>
Then let's see what happens when SparkEV starts shedding weight. Certainly, things like passenger seats and rear hatch / doors would be hundreds of pounds. I plot from 0 lb to 1000 lb removed in 100 lb increments.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiUZPNdTxf5ZVCe-DYu49SYFo3D5tBsPXUnFYVwUDW1lcsheXPV6hXmjS2IeeuxY4zjHaIfhTiuk8zJwQ7czJFufVR8giXcuSwL7AvqUFZe9KVu2n4XQGamnxbiGHp-8aCTW4Z2KZG9sPFl/s1600/05+2015+weight+loss.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiUZPNdTxf5ZVCe-DYu49SYFo3D5tBsPXUnFYVwUDW1lcsheXPV6hXmjS2IeeuxY4zjHaIfhTiuk8zJwQ7czJFufVR8giXcuSwL7AvqUFZe9KVu2n4XQGamnxbiGHp-8aCTW4Z2KZG9sPFl/s1600/05+2015+weight+loss.gif" /></a></div>
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<table border="1">
<tbody>
<tr bgcolor="#C0C0C0"><td width="64">speed (mph)</td><td width="64">2016lb time (sec)</td><td width="64">2016lb gforce</td><td width="64">2116lb time (sec)</td><td width="64">2116lb gforce</td><td width="64">2216lb time (sec)</td><td width="64">2216lb gforce</td><td width="64">2316lb time (sec)</td><td width="64">2316lb gforce</td><td width="64">2416lb time (sec)</td><td width="64">2416lb gforce</td><td width="64">2516lb time (sec)</td><td width="64">2516lb gforce</td><td width="64">2616lb time (sec)</td><td width="64">2616lb gforce</td><td width="64">2716lb time (sec)</td><td width="64">2716lb gforce</td><td width="64">2816lb time (sec)</td><td width="64">2816lb gforce</td><td width="64">2916lb time (sec)</td><td width="64">2916lb gforce
</td></tr>
<tr><td width="64">0</td><td width="64">0.00</td><td width="64">0.61</td><td width="64">0.00</td><td width="64">0.58</td><td width="64">0.00</td><td width="64">0.55</td><td width="64">0.00</td><td width="64">0.53</td><td width="64">0.00</td><td width="64">0.51</td><td width="64">0.00</td><td width="64">0.49</td><td width="64">0.00</td><td width="64">0.47</td><td width="64">0.00</td><td width="64">0.45</td><td width="64">0.00</td><td width="64">0.43</td><td width="64">0.00</td><td width="64">0.42</td></tr>
<tr><td width="64">5</td><td width="64">0.36</td><td width="64">0.64</td><td width="64">0.38</td><td width="64">0.61</td><td width="64">0.39</td><td width="64">0.58</td><td width="64">0.41</td><td width="64">0.56</td><td width="64">0.43</td><td width="64">0.54</td><td width="64">0.45</td><td width="64">0.51</td><td width="64">0.47</td><td width="64">0.49</td><td width="64">0.48</td><td width="64">0.47</td><td width="64">0.50</td><td width="64">0.46</td><td width="64">0.52</td><td width="64">0.44</td></tr>
<tr><td width="64">10</td><td width="64">0.71</td><td width="64">0.64</td><td width="64">0.75</td><td width="64">0.61</td><td width="64">0.78</td><td width="64">0.58</td><td width="64">0.82</td><td width="64">0.56</td><td width="64">0.86</td><td width="64">0.53</td><td width="64">0.89</td><td width="64">0.51</td><td width="64">0.93</td><td width="64">0.49</td><td width="64">0.96</td><td width="64">0.47</td><td width="64">1.00</td><td width="64">0.46</td><td width="64">1.04</td><td width="64">0.44</td></tr>
<tr><td width="64">15</td><td width="64">1.07</td><td width="64">0.64</td><td width="64">1.12</td><td width="64">0.61</td><td width="64">1.17</td><td width="64">0.58</td><td width="64">1.23</td><td width="64">0.56</td><td width="64">1.28</td><td width="64">0.53</td><td width="64">1.34</td><td width="64">0.51</td><td width="64">1.39</td><td width="64">0.49</td><td width="64">1.45</td><td width="64">0.47</td><td width="64">1.50</td><td width="64">0.46</td><td width="64">1.55</td><td width="64">0.44</td></tr>
<tr><td width="64">20</td><td width="64">1.42</td><td width="64">0.64</td><td width="64">1.49</td><td width="64">0.61</td><td width="64">1.57</td><td width="64">0.58</td><td width="64">1.64</td><td width="64">0.55</td><td width="64">1.71</td><td width="64">0.53</td><td width="64">1.78</td><td width="64">0.51</td><td width="64">1.86</td><td width="64">0.49</td><td width="64">1.93</td><td width="64">0.47</td><td width="64">2.00</td><td width="64">0.45</td><td width="64">2.07</td><td width="64">0.44</td></tr>
<tr><td width="64">25</td><td width="64">1.78</td><td width="64">0.64</td><td width="64">1.87</td><td width="64">0.61</td><td width="64">1.96</td><td width="64">0.58</td><td width="64">2.05</td><td width="64">0.55</td><td width="64">2.14</td><td width="64">0.53</td><td width="64">2.23</td><td width="64">0.51</td><td width="64">2.32</td><td width="64">0.49</td><td width="64">2.41</td><td width="64">0.47</td><td width="64">2.50</td><td width="64">0.45</td><td width="64">2.59</td><td width="64">0.44</td></tr>
<tr><td width="64">30</td><td width="64">2.14</td><td width="64">0.64</td><td width="64">2.25</td><td width="64">0.61</td><td width="64">2.35</td><td width="64">0.58</td><td width="64">2.46</td><td width="64">0.55</td><td width="64">2.57</td><td width="64">0.53</td><td width="64">2.68</td><td width="64">0.51</td><td width="64">2.79</td><td width="64">0.49</td><td width="64">2.90</td><td width="64">0.47</td><td width="64">3.01</td><td width="64">0.45</td><td width="64">3.12</td><td width="64">0.44</td></tr>
<tr><td width="64">35</td><td width="64">2.50</td><td width="64">0.62</td><td width="64">2.63</td><td width="64">0.59</td><td width="64">2.75</td><td width="64">0.56</td><td width="64">2.88</td><td width="64">0.54</td><td width="64">3.01</td><td width="64">0.52</td><td width="64">3.13</td><td width="64">0.50</td><td width="64">3.26</td><td width="64">0.48</td><td width="64">3.39</td><td width="64">0.46</td><td width="64">3.52</td><td width="64">0.44</td><td width="64">3.64</td><td width="64">0.43</td></tr>
<tr><td width="64">40</td><td width="64">2.88</td><td width="64">0.60</td><td width="64">3.02</td><td width="64">0.57</td><td width="64">3.17</td><td width="64">0.54</td><td width="64">3.31</td><td width="64">0.52</td><td width="64">3.46</td><td width="64">0.50</td><td width="64">3.61</td><td width="64">0.48</td><td width="64">3.75</td><td width="64">0.46</td><td width="64">3.90</td><td width="64">0.44</td><td width="64">4.04</td><td width="64">0.42</td><td width="64">4.19</td><td width="64">0.41</td></tr>
<tr><td width="64">45</td><td width="64">3.28</td><td width="64">0.55</td><td width="64">3.44</td><td width="64">0.52</td><td width="64">3.61</td><td width="64">0.50</td><td width="64">3.77</td><td width="64">0.48</td><td width="64">3.94</td><td width="64">0.46</td><td width="64">4.11</td><td width="64">0.44</td><td width="64">4.27</td><td width="64">0.42</td><td width="64">4.44</td><td width="64">0.41</td><td width="64">4.61</td><td width="64">0.39</td><td width="64">4.77</td><td width="64">0.38</td></tr>
<tr><td width="64">50</td><td width="64">3.73</td><td width="64">0.47</td><td width="64">3.92</td><td width="64">0.45</td><td width="64">4.11</td><td width="64">0.43</td><td width="64">4.30</td><td width="64">0.41</td><td width="64">4.49</td><td width="64">0.39</td><td width="64">4.68</td><td width="64">0.38</td><td width="64">4.87</td><td width="64">0.36</td><td width="64">5.06</td><td width="64">0.35</td><td width="64">5.25</td><td width="64">0.33</td><td width="64">5.44</td><td width="64">0.32</td></tr>
<tr><td width="64">55</td><td width="64">4.26</td><td width="64">0.41</td><td width="64">4.48</td><td width="64">0.39</td><td width="64">4.69</td><td width="64">0.37</td><td width="64">4.91</td><td width="64">0.35</td><td width="64">5.13</td><td width="64">0.34</td><td width="64">5.34</td><td width="64">0.32</td><td width="64">5.56</td><td width="64">0.31</td><td width="64">5.78</td><td width="64">0.30</td><td width="64">6.00</td><td width="64">0.29</td><td width="64">6.21</td><td width="64">0.28</td></tr>
<tr><td width="64">60</td><td width="64">4.88</td><td width="64">0.35</td><td width="64">5.12</td><td width="64">0.34</td><td width="64">5.37</td><td width="64">0.32</td><td width="64">5.62</td><td width="64">0.31</td><td width="64">5.86</td><td width="64">0.29</td><td width="64">6.11</td><td width="64">0.28</td><td width="64">6.36</td><td width="64">0.27</td><td width="64">6.61</td><td width="64">0.26</td><td width="64">6.86</td><td width="64">0.25</td><td width="64">7.11</td><td width="64">0.24</td></tr>
<tr><td width="64">65</td><td width="64">5.58</td><td width="64">0.31</td><td width="64">5.86</td><td width="64">0.29</td><td width="64">6.15</td><td width="64">0.28</td><td width="64">6.43</td><td width="64">0.27</td><td width="64">6.71</td><td width="64">0.25</td><td width="64">7.00</td><td width="64">0.24</td><td width="64">7.29</td><td width="64">0.23</td><td width="64">7.57</td><td width="64">0.22</td><td width="64">7.86</td><td width="64">0.22</td><td width="64">8.15</td><td width="64">0.21</td></tr>
<tr><td width="64">70</td><td width="64">6.39</td><td width="64">0.27</td><td width="64">6.72</td><td width="64">0.25</td><td width="64">7.04</td><td width="64">0.24</td><td width="64">7.37</td><td width="64">0.23</td><td width="64">7.70</td><td width="64">0.22</td><td width="64">8.02</td><td width="64">0.21</td><td width="64">8.35</td><td width="64">0.20</td><td width="64">8.68</td><td width="64">0.19</td><td width="64">9.01</td><td width="64">0.19</td><td width="64">9.34</td><td width="64">0.18</td></tr>
<tr><td width="64">75</td><td width="64">7.33</td><td width="64">0.23</td><td width="64">7.71</td><td width="64">0.22</td><td width="64">8.08</td><td width="64">0.21</td><td width="64">8.45</td><td width="64">0.20</td><td width="64">8.83</td><td width="64">0.19</td><td width="64">9.21</td><td width="64">0.18</td><td width="64">9.58</td><td width="64">0.17</td><td width="64">9.96</td><td width="64">0.17</td><td width="64">10.34</td><td width="64">0.16</td><td width="64">10.72</td><td width="64">0.16</td></tr>
<tr><td width="64">80</td><td width="64">8.41</td><td width="64">0.20</td><td width="64">8.84</td><td width="64">0.19</td><td width="64">9.27</td><td width="64">0.18</td><td width="64">9.70</td><td width="64">0.17</td><td width="64">10.14</td><td width="64">0.17</td><td width="64">10.57</td><td width="64">0.16</td><td width="64">11.01</td><td width="64">0.15</td><td width="64">11.44</td><td width="64">0.15</td><td width="64">11.88</td><td width="64">0.14</td><td width="64">12.32</td><td width="64">0.14</td></tr>
<tr><td width="64">85</td><td width="64">9.65</td><td width="64">0.17</td><td width="64">10.15</td><td width="64">0.16</td><td width="64">10.64</td><td width="64">0.16</td><td width="64">11.14</td><td width="64">0.15</td><td width="64">11.64</td><td width="64">0.14</td><td width="64">12.14</td><td width="64">0.14</td><td width="64">12.64</td><td width="64">0.13</td><td width="64">13.15</td><td width="64">0.12</td><td width="64">13.65</td><td width="64">0.12</td><td width="64">14.16</td><td width="64">0.12</td></tr>
<tr><td width="64">90</td><td width="64">11.37</td><td width="64">0.11</td><td width="64">11.96</td><td width="64">0.10</td><td width="64">12.55</td><td width="64">0.10</td><td width="64">13.14</td><td width="64">0.09</td><td width="64">13.73</td><td width="64">0.09</td><td width="64">14.33</td><td width="64">0.08</td><td width="64">14.93</td><td width="64">0.08</td><td width="64">15.53</td><td width="64">0.08</td><td width="64">16.13</td><td width="64">0.07</td><td width="64">16.73</td><td width="64">0.07</td></tr>
</tbody></table>
<br />
With 1000 lb lighter, SparkEV would do 0-60 MPH in under 5 seconds, quicker than Tesla S70! But 1000 lb lighter is not realistic since that probably wouldn't be street legal. More realistic would be 200 lb lighter at most (ie. train your dog to drive!). That would result in 6.86 seconds. Chevy stated that Bolt will be under 7 seconds, so could SparkEV on mild diet be quicker than Bolt? At least for 0-30 MPH of 3 seconds and taking 0.17/0.26 second discrepancy into account, SparkEV would be quicker than Bolt's 2.9 seconds. We'll explore Bolt later in this post.<br />
<br />
<b>Climbing acceleration</b><br />
<br />
What happens when accelerating on hills? Obviously, it will be slower, but how much slower will it be? I plot 2015 SparkEV with 150 lb rider over various percent grades of hills from 0% (flat road) to 20%.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNVhkyj-jUeJr7u8YVSgNMQIAZrpve3WHQq4B26X_1EgYfS4VHe4ds5nsaPCd3hhyCmVSSZhbA74_mkTAfbMuMdILdX9JVVUlKox-nXyOfVaKIcYWXSKtcF7GbSERlig-2qlsL1vcXjdx0/s1600/06+hill+accelerate.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNVhkyj-jUeJr7u8YVSgNMQIAZrpve3WHQq4B26X_1EgYfS4VHe4ds5nsaPCd3hhyCmVSSZhbA74_mkTAfbMuMdILdX9JVVUlKox-nXyOfVaKIcYWXSKtcF7GbSERlig-2qlsL1vcXjdx0/s1600/06+hill+accelerate.gif" /></a></div>
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<table border="1">
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<tr bgcolor="#C0C0C0"><td width="64">2015 SparkEV acceleration over speed (mph)</td><td width="64">0% grade time (sec)</td><td width="64">0% grade gforce</td><td width="64">1% grade time (sec)</td><td width="64">1% grade gforce</td><td width="64">2% grade time (sec)</td><td width="64">2% grade gforce</td><td width="64">3% grade time (sec)</td><td width="64">3% grade gforce</td><td width="64">5% grade time (sec)</td><td width="64">5% grade gforce</td><td width="64">8% grade time (sec)</td><td width="64">8% grade gforce</td><td width="64">13% grade time (sec)</td><td width="64">13% grade gforce</td><td width="64">21% grade time (sec)</td><td width="64">21% grade gforce
</td></tr>
<tr><td width="64">0</td><td width="64">0.00</td><td width="64">0.40</td><td width="64">0.00</td><td width="64">0.39</td><td width="64">0.00</td><td width="64">0.38</td><td width="64">0.00</td><td width="64">0.37</td><td width="64">0.00</td><td width="64">0.35</td><td width="64">0.00</td><td width="64">0.33</td><td width="64">0.00</td><td width="64">0.28</td><td width="64">0.00</td><td width="64">0.20</td></tr>
<tr><td width="64">5</td><td width="64">0.54</td><td width="64">0.43</td><td width="64">0.55</td><td width="64">0.42</td><td width="64">0.56</td><td width="64">0.41</td><td width="64">0.58</td><td width="64">0.40</td><td width="64">0.61</td><td width="64">0.38</td><td width="64">0.66</td><td width="64">0.35</td><td width="64">0.77</td><td width="64">0.30</td><td width="64">1.05</td><td width="64">0.22</td></tr>
<tr><td width="64">10</td><td width="64">1.07</td><td width="64">0.43</td><td width="64">1.10</td><td width="64">0.42</td><td width="64">1.13</td><td width="64">0.41</td><td width="64">1.15</td><td width="64">0.40</td><td width="64">1.22</td><td width="64">0.38</td><td width="64">1.32</td><td width="64">0.35</td><td width="64">1.54</td><td width="64">0.30</td><td width="64">2.08</td><td width="64">0.22</td></tr>
<tr><td width="64">15</td><td width="64">1.61</td><td width="64">0.42</td><td width="64">1.65</td><td width="64">0.41</td><td width="64">1.69</td><td width="64">0.40</td><td width="64">1.73</td><td width="64">0.39</td><td width="64">1.82</td><td width="64">0.37</td><td width="64">1.98</td><td width="64">0.35</td><td width="64">2.31</td><td width="64">0.30</td><td width="64">3.11</td><td width="64">0.22</td></tr>
<tr><td width="64">20</td><td width="64">2.15</td><td width="64">0.42</td><td width="64">2.20</td><td width="64">0.41</td><td width="64">2.25</td><td width="64">0.40</td><td width="64">2.31</td><td width="64">0.39</td><td width="64">2.43</td><td width="64">0.37</td><td width="64">2.64</td><td width="64">0.34</td><td width="64">3.08</td><td width="64">0.29</td><td width="64">4.16</td><td width="64">0.22</td></tr>
<tr><td width="64">25</td><td width="64">2.68</td><td width="64">0.42</td><td width="64">2.75</td><td width="64">0.41</td><td width="64">2.82</td><td width="64">0.40</td><td width="64">2.89</td><td width="64">0.39</td><td width="64">3.04</td><td width="64">0.37</td><td width="64">3.31</td><td width="64">0.34</td><td width="64">3.86</td><td width="64">0.29</td><td width="64">5.20</td><td width="64">0.22</td></tr>
<tr><td width="64">30</td><td width="64">3.23</td><td width="64">0.42</td><td width="64">3.30</td><td width="64">0.41</td><td width="64">3.38</td><td width="64">0.40</td><td width="64">3.47</td><td width="64">0.39</td><td width="64">3.66</td><td width="64">0.37</td><td width="64">3.97</td><td width="64">0.34</td><td width="64">4.63</td><td width="64">0.29</td><td width="64">6.26</td><td width="64">0.22</td></tr>
<tr><td width="64">35</td><td width="64">3.77</td><td width="64">0.41</td><td width="64">3.86</td><td width="64">0.40</td><td width="64">3.96</td><td width="64">0.39</td><td width="64">4.06</td><td width="64">0.38</td><td width="64">4.28</td><td width="64">0.36</td><td width="64">4.65</td><td width="64">0.33</td><td width="64">5.43</td><td width="64">0.28</td><td width="64">7.34</td><td width="64">0.21</td></tr>
<tr><td width="64">40</td><td width="64">4.34</td><td width="64">0.40</td><td width="64">4.44</td><td width="64">0.39</td><td width="64">4.56</td><td width="64">0.38</td><td width="64">4.67</td><td width="64">0.37</td><td width="64">4.92</td><td width="64">0.35</td><td width="64">5.36</td><td width="64">0.32</td><td width="64">6.26</td><td width="64">0.27</td><td width="64">8.50</td><td width="64">0.19</td></tr>
<tr><td width="64">45</td><td width="64">4.94</td><td width="64">0.36</td><td width="64">5.06</td><td width="64">0.35</td><td width="64">5.19</td><td width="64">0.34</td><td width="64">5.33</td><td width="64">0.33</td><td width="64">5.62</td><td width="64">0.31</td><td width="64">6.12</td><td width="64">0.28</td><td width="64">7.18</td><td width="64">0.24</td><td width="64">9.82</td><td width="64">0.16</td></tr>
<tr><td width="64">50</td><td width="64">5.63</td><td width="64">0.31</td><td width="64">5.77</td><td width="64">0.30</td><td width="64">5.92</td><td width="64">0.29</td><td width="64">6.08</td><td width="64">0.28</td><td width="64">6.43</td><td width="64">0.26</td><td width="64">7.03</td><td width="64">0.23</td><td width="64">8.30</td><td width="64">0.18</td><td width="64">11.64</td><td width="64">0.11</td></tr>
<tr><td width="64">55</td><td width="64">6.43</td><td width="64">0.27</td><td width="64">6.61</td><td width="64">0.26</td><td width="64">6.79</td><td width="64">0.25</td><td width="64">6.98</td><td width="64">0.24</td><td width="64">7.40</td><td width="64">0.22</td><td width="64">8.15</td><td width="64">0.19</td><td width="64">9.78</td><td width="64">0.14</td><td width="64">14.61</td><td width="64">0.06</td></tr>
<tr><td width="64">60</td><td width="64">7.36</td><td width="64">0.23</td><td width="64">7.57</td><td width="64">0.22</td><td width="64">7.80</td><td width="64">0.21</td><td width="64">8.04</td><td width="64">0.20</td><td width="64">8.57</td><td width="64">0.18</td><td width="64">9.52</td><td width="64">0.15</td><td width="64">11.75</td><td width="64">0.10</td><td width="64">20.71</td><td width="64">0.03</td></tr>
<tr><td width="64">65</td><td width="64">8.43</td><td width="64">0.20</td><td width="64">8.70</td><td width="64">0.19</td><td width="64">8.98</td><td width="64">0.18</td><td width="64">9.29</td><td width="64">0.17</td><td width="64">9.97</td><td width="64">0.15</td><td width="64">11.24</td><td width="64">0.12</td><td width="64">14.49</td><td width="64">0.07</td><td width="64">719.16</td><td width="64">0.00</td></tr>
<tr><td width="64">70</td><td width="64">9.67</td><td width="64">0.17</td><td width="64">10.01</td><td width="64">0.16</td><td width="64">10.37</td><td width="64">0.15</td><td width="64">10.77</td><td width="64">0.14</td><td width="64">11.68</td><td width="64">0.12</td><td width="64">13.44</td><td width="64">0.09</td><td width="64">18.70</td><td width="64">0.05</td><td width="64">1000.00</td><td width="64">0.00</td></tr>
<tr><td width="64">75</td><td width="64">11.11</td><td width="64">0.15</td><td width="64">11.54</td><td width="64">0.14</td><td width="64">12.01</td><td width="64">0.13</td><td width="64">12.54</td><td width="64">0.12</td><td width="64">13.77</td><td width="64">0.10</td><td width="64">16.32</td><td width="64">0.07</td><td width="64">26.60</td><td width="64">0.02</td><td width="64">1000.00</td><td width="64">0.00</td></tr>
<tr><td width="64">80</td><td width="64">12.76</td><td width="64">0.13</td><td width="64">13.32</td><td width="64">0.12</td><td width="64">13.95</td><td width="64">0.11</td><td width="64">14.65</td><td width="64">0.10</td><td width="64">16.37</td><td width="64">0.08</td><td width="64">20.26</td><td width="64">0.05</td><td width="64">68.55</td><td width="64">0.00</td><td width="64">1000.00</td><td width="64">0.00</td></tr>
<tr><td width="64">85</td><td width="64">14.67</td><td width="64">0.11</td><td width="64">15.41</td><td width="64">0.10</td><td width="64">16.24</td><td width="64">0.09</td><td width="64">17.21</td><td width="64">0.08</td><td width="64">19.66</td><td width="64">0.06</td><td width="64">26.12</td><td width="64">0.03</td><td width="64">1000.00</td><td width="64">0.00</td><td width="64">1000.00</td><td width="64">0.00</td></tr>
<tr><td width="64">90</td><td width="64">17.34</td><td width="64">0.07</td><td width="64">18.45</td><td width="64">0.06</td><td width="64">19.78</td><td width="64">0.05</td><td width="64">21.45</td><td width="64">0.04</td><td width="64">27.18</td><td width="64">0.02</td><td width="64">1000.00</td><td width="64">0.00</td><td width="64">1000.00</td><td width="64">0.00</td><td width="64">1000.00</td><td width="64">0.00</td></tr>
</tbody></table>
<br />
Few interesting observations can be made.<br />
<br />
1. Leaf and eGolf have 0-60 MPH time of about 10 seconds. That's like SparkEV accelerating on 8% grade. 8% grade is steeper than most roads, like "grape vine" (aka, Tejon pass) in SoCal.<br />
<br />
2. 0-60 MPH time for iMiev is about 13 seconds and tiny 2 seater like SmartED has 11.5 seconds. That's like SparkEV accelerating on 13% to 14% grade. That is steeper than many driveways.<br />
<br />
3. Chevy's disgraceful Iron Duke Camaro supposedly did 0-60 MPH in 20 seconds. That's about SparkEV on 20% grade. 20% grade is incredibly steep when you see it in person, about 1000 ft rise for every mile driven, almost like airplane take off.<br />
<br />
One should keep in mind that these are only 0-60 MPH times. Those cars may be tuned for lower speed acceleration, and could be quicker than SparkEV on hill at different speeds (ie, Leaf to 30 MPH). Still, SparkEV accelerating up a hill could be kicking butt of many cars on flat road.<br />
<br />
<b>Climbing ability</b><br />
<br />
In previous blog post "SparkEV range polynomial climbing hill", I explored SparkEV's climbing ability.<br />
<br />
<a href="http://sparkev.blogspot.com/2016/03/range-polynomial-climbing-hill.html">http://sparkev.blogspot.com/2016/03/range-polynomial-climbing-hill.html</a><br />
<br />
While maximum climbing was left as homework for the reader, it's not possible to know the maximum without knowing the torque at the wheels, which this blog post is based on. Below plot shows maximum climbing ability over various weights. Again, lowest weight includes 150 lb driver on 2015 SparkEV and heaviest is about GVWR case.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjwzpcwL2wnJQTGUZ9mI702Uyqh-F6O2dXGckHhR5MJobEHRnAIdBBRh7_XbPg6hjIdslHzxdKBLWZ3c25gHiCbyUG12bCsUGS3WXGgdj_sly684onAOihnIKyoE1m9g4ZwubA2mdLpD9Qm/s1600/07+hill+grade.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjwzpcwL2wnJQTGUZ9mI702Uyqh-F6O2dXGckHhR5MJobEHRnAIdBBRh7_XbPg6hjIdslHzxdKBLWZ3c25gHiCbyUG12bCsUGS3WXGgdj_sly684onAOihnIKyoE1m9g4ZwubA2mdLpD9Qm/s1600/07+hill+grade.gif" /></a></div>
<div>
<br /></div>
<table border="1">
<tbody>
<tr bgcolor="#C0C0C0"><td width="64">speed (mph)</td><td width="64">3016lb climb (%)</td><td width="64">3116lb climb (%)</td><td width="64">3216lb climb (%)</td><td width="64">3316lb climb (%)</td><td width="64">3416lb climb (%)</td><td width="64">3516lb climb (%)</td><td width="64">3616lb climb (%)</td><td width="64">3716lb climb (%)
</td></tr>
<tr><td width="64">0</td><td width="64">25.00</td><td width="64">25.00</td><td width="64">25.00</td><td width="64">25.00</td><td width="64">25.00</td><td width="64">25.00</td><td width="64">25.00</td><td width="64">25.00</td></tr>
<tr><td width="64">5</td><td width="64">47.17</td><td width="64">45.30</td><td width="64">43.57</td><td width="64">41.99</td><td width="64">40.51</td><td width="64">39.15</td><td width="64">37.87</td><td width="64">36.68</td></tr>
<tr><td width="64">10</td><td width="64">47.04</td><td width="64">45.18</td><td width="64">43.46</td><td width="64">41.88</td><td width="64">40.41</td><td width="64">39.05</td><td width="64">37.78</td><td width="64">36.59</td></tr>
<tr><td width="64">15</td><td width="64">46.92</td><td width="64">45.06</td><td width="64">43.35</td><td width="64">41.77</td><td width="64">40.31</td><td width="64">38.95</td><td width="64">37.68</td><td width="64">36.50</td></tr>
<tr><td width="64">20</td><td width="64">46.75</td><td width="64">44.89</td><td width="64">43.19</td><td width="64">41.62</td><td width="64">40.17</td><td width="64">38.81</td><td width="64">37.55</td><td width="64">36.37</td></tr>
<tr><td width="64">25</td><td width="64">46.52</td><td width="64">44.68</td><td width="64">42.99</td><td width="64">41.43</td><td width="64">39.98</td><td width="64">38.64</td><td width="64">37.38</td><td width="64">36.21</td></tr>
<tr><td width="64">30</td><td width="64">46.51</td><td width="64">44.67</td><td width="64">42.98</td><td width="64">41.42</td><td width="64">39.97</td><td width="64">38.63</td><td width="64">37.38</td><td width="64">36.20</td></tr>
<tr><td width="64">35</td><td width="64">45.17</td><td width="64">43.40</td><td width="64">41.77</td><td width="64">40.26</td><td width="64">38.87</td><td width="64">37.57</td><td width="64">36.36</td><td width="64">35.22</td></tr>
<tr><td width="64">40</td><td width="64">43.06</td><td width="64">41.39</td><td width="64">39.86</td><td width="64">38.44</td><td width="64">37.12</td><td width="64">35.89</td><td width="64">34.74</td><td width="64">33.67</td></tr>
<tr><td width="64">45</td><td width="64">39.08</td><td width="64">37.60</td><td width="64">36.24</td><td width="64">34.97</td><td width="64">33.80</td><td width="64">32.70</td><td width="64">31.67</td><td width="64">30.70</td></tr>
<tr><td width="64">50</td><td width="64">32.84</td><td width="64">31.64</td><td width="64">30.53</td><td width="64">29.49</td><td width="64">28.52</td><td width="64">27.62</td><td width="64">26.77</td><td width="64">25.97</td></tr>
<tr><td width="64">55</td><td width="64">27.87</td><td width="64">26.87</td><td width="64">25.95</td><td width="64">25.08</td><td width="64">24.27</td><td width="64">23.51</td><td width="64">22.80</td><td width="64">22.12</td></tr>
<tr><td width="64">60</td><td width="64">23.91</td><td width="64">23.06</td><td width="64">22.28</td><td width="64">21.54</td><td width="64">20.85</td><td width="64">20.20</td><td width="64">19.59</td><td width="64">19.02</td></tr>
<tr><td width="64">65</td><td width="64">20.55</td><td width="64">19.83</td><td width="64">19.16</td><td width="64">18.53</td><td width="64">17.94</td><td width="64">17.38</td><td width="64">16.86</td><td width="64">16.36</td></tr>
<tr><td width="64">70</td><td width="64">17.69</td><td width="64">17.07</td><td width="64">16.49</td><td width="64">15.95</td><td width="64">15.44</td><td width="64">14.96</td><td width="64">14.51</td><td width="64">14.08</td></tr>
<tr><td width="64">75</td><td width="64">15.21</td><td width="64">14.68</td><td width="64">14.18</td><td width="64">13.71</td><td width="64">13.27</td><td width="64">12.86</td><td width="64">12.47</td><td width="64">12.10</td></tr>
<tr><td width="64">80</td><td width="64">13.23</td><td width="64">12.76</td><td width="64">12.33</td><td width="64">11.92</td><td width="64">11.54</td><td width="64">11.18</td><td width="64">10.84</td><td width="64">10.51</td></tr>
<tr><td width="64">85</td><td width="64">11.21</td><td width="64">10.81</td><td width="64">10.44</td><td width="64">10.09</td><td width="64">9.77</td><td width="64">9.46</td><td width="64">9.17</td><td width="64">8.89</td></tr>
<tr><td width="64">90</td><td width="64">6.76</td><td width="64">6.51</td><td width="64">6.27</td><td width="64">6.05</td><td width="64">5.84</td><td width="64">5.65</td><td width="64">5.46</td><td width="64">5.29</td></tr>
</tbody></table>
<br />
Chevy claims maximum grade at start is only about 25%. But if we go by the torque available at the wheels, it's closer to 45%! Why the discrepancy? Maybe the computer limits the torque at low speed? Regardless, I just set it to 25% at 0 MPH in the analysis.<br />
<br />
Note that climbing ability is less than 7% grade at 90 MPH, the maximum speed of the car limited by electronics. But even if it's not limited by electronics, maximum speed may not be much more. Torque graph drops almost linearly while the force to overcome drag would increase proportional to the square of speed (power is cube of speed). I suspect SparkEV won't go much faster than 95 MPH, if that, even without electronic speed limit.<br />
<br />
<div>
<div>
<b>Theoretical top speed</b></div>
<div>
<br /></div>
<div>
Often the forum discussion turns to top speed of SparkEV. It's electronically limited to 90 MPH, but if there is no such restriction, what would be the top speed? Simply going by gears, and assuming the motor can spin to 10,000 RPM like other EV motors, it yields top speed close to 200 MPH! Obviously, that won't happen due to drag forces. Since we have the driving force, we can extend (ie, make up numbers, my favorite activity) to see at what speed the driving force would not be enough to overcome the drag force.</div>
</div>
<div>
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgf0UlK-bdi6ZwQ8hgLBJQpgdXszrUt10nSDRUn976n7oU5Cgo_jhdoiUxVp37Zs5SY-qW8FjJ2GXNGq-uxqvol7qj6nXtKS228b46_b85SaxRzL49pBwY4SnD_v8Y0Q5iBRrRfOJf4kBDk/s1600/11+peak+speed.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgf0UlK-bdi6ZwQ8hgLBJQpgdXszrUt10nSDRUn976n7oU5Cgo_jhdoiUxVp37Zs5SY-qW8FjJ2GXNGq-uxqvol7qj6nXtKS228b46_b85SaxRzL49pBwY4SnD_v8Y0Q5iBRrRfOJf4kBDk/s1600/11+peak+speed.gif" /></a></div>
<div>
<div>
<br /></div>
<div>
What I do is to take the last few seemingly linear samples of torque data (blue plot) and interpolate a straight line from there (green plot). Then I plot the drag data (red plot) and see where they intersect. That occurs at about 96 MPH. But even if there's no drag, the motor would top out at about 103 MPH. Were they shooting for 105 MPH to match it to 105 kW the motor is capable of? Maybe this is a little Easter egg for us! Or not; remember, these are all made up numbers.</div>
<div>
<br /></div>
<div>
<b>Bolt guess</b></div>
</div>
<br />
From Chevy's web site, Bolt is expected to be 2.9 seconds for 0-30 MPH. Chevy claims under 7 seconds for 0-60 MPH, but they don't say how much less. Something we can guess is Bolt's performance if it has torque profile of SparkEV. We simply scale SparkEV's torque curve to Bolt's peak torque and run the analysis. Yes, it's a total guess, but what the heck, let's see what happens.<br />
<br />
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<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<br />
<table border="1">
<tbody>
<tr bgcolor="#C0C0C0"><td width="64">speed (mph)</td><td width="64">bolt time (sec)</td><td width="64">bolt gforce</td><td width="64">bolt no driver time (sec)</td><td width="64">bolt no driver gforce</td><td width="64">bolt 75lb driver time (sec)</td><td width="64">bolt 75lb driver gforce</td><td width="64">bolt no drag time (sec)</td><td width="64">bolt no drag gforce
</td></tr>
<tr><td width="64">0</td><td width="64">0.00</td><td width="64">0.44</td><td width="64">0.00</td><td width="64">0.46</td><td width="64">0.00</td><td width="64">0.45</td><td width="64">0.00</td><td width="64">0.44</td></tr>
<tr><td width="64">5</td><td width="64">0.50</td><td width="64">0.46</td><td width="64">0.48</td><td width="64">0.48</td><td width="64">0.49</td><td width="64">0.47</td><td width="64">0.50</td><td width="64">0.46</td></tr>
<tr><td width="64">10</td><td width="64">0.99</td><td width="64">0.46</td><td width="64">0.95</td><td width="64">0.48</td><td width="64">0.97</td><td width="64">0.47</td><td width="64">0.99</td><td width="64">0.46</td></tr>
<tr><td width="64">15</td><td width="64">1.49</td><td width="64">0.46</td><td width="64">1.43</td><td width="64">0.48</td><td width="64">1.46</td><td width="64">0.47</td><td width="64">1.49</td><td width="64">0.46</td></tr>
<tr><td width="64">20</td><td width="64">1.98</td><td width="64">0.46</td><td width="64">1.90</td><td width="64">0.48</td><td width="64">1.94</td><td width="64">0.47</td><td width="64">1.98</td><td width="64">0.46</td></tr>
<tr><td width="64">25</td><td width="64">2.48</td><td width="64">0.46</td><td width="64">2.38</td><td width="64">0.48</td><td width="64">2.43</td><td width="64">0.47</td><td width="64">2.48</td><td width="64">0.46</td></tr>
<tr><td width="64">30</td><td width="64">2.98</td><td width="64">0.46</td><td width="64">2.86</td><td width="64">0.48</td><td width="64">2.92</td><td width="64">0.47</td><td width="64">2.97</td><td width="64">0.46</td></tr>
<tr><td width="64">35</td><td width="64">3.48</td><td width="64">0.45</td><td width="64">3.34</td><td width="64">0.47</td><td width="64">3.41</td><td width="64">0.46</td><td width="64">3.47</td><td width="64">0.45</td></tr>
<tr><td width="64">40</td><td width="64">4.01</td><td width="64">0.43</td><td width="64">3.84</td><td width="64">0.45</td><td width="64">3.92</td><td width="64">0.44</td><td width="64">3.98</td><td width="64">0.44</td></tr>
<tr><td width="64">45</td><td width="64">4.56</td><td width="64">0.40</td><td width="64">4.37</td><td width="64">0.41</td><td width="64">4.47</td><td width="64">0.41</td><td width="64">4.51</td><td width="64">0.41</td></tr>
<tr><td width="64">50</td><td width="64">5.19</td><td width="64">0.34</td><td width="64">4.97</td><td width="64">0.36</td><td width="64">5.08</td><td width="64">0.35</td><td width="64">5.12</td><td width="64">0.36</td></tr>
<tr><td width="64">55</td><td width="64">5.92</td><td width="64">0.30</td><td width="64">5.67</td><td width="64">0.31</td><td width="64">5.79</td><td width="64">0.30</td><td width="64">5.81</td><td width="64">0.31</td></tr>
<tr><td width="64">60</td><td width="64">6.75</td><td width="64">0.26</td><td width="64">6.47</td><td width="64">0.27</td><td width="64">6.61</td><td width="64">0.26</td><td width="64">6.59</td><td width="64">0.28</td></tr>
<tr><td width="64">65</td><td width="64">7.71</td><td width="64">0.23</td><td width="64">7.39</td><td width="64">0.24</td><td width="64">7.55</td><td width="64">0.23</td><td width="64">7.46</td><td width="64">0.25</td></tr>
<tr><td width="64">70</td><td width="64">8.80</td><td width="64">0.20</td><td width="64">8.44</td><td width="64">0.21</td><td width="64">8.62</td><td width="64">0.20</td><td width="64">8.42</td><td width="64">0.23</td></tr>
<tr><td width="64">75</td><td width="64">10.05</td><td width="64">0.17</td><td width="64">9.63</td><td width="64">0.18</td><td width="64">9.84</td><td width="64">0.18</td><td width="64">9.48</td><td width="64">0.21</td></tr>
<tr><td width="64">80</td><td width="64">11.46</td><td width="64">0.16</td><td width="64">10.98</td><td width="64">0.16</td><td width="64">11.22</td><td width="64">0.16</td><td width="64">10.63</td><td width="64">0.19</td></tr>
<tr><td width="64">85</td><td width="64">13.04</td><td width="64">0.14</td><td width="64">12.50</td><td width="64">0.14</td><td width="64">12.77</td><td width="64">0.14</td><td width="64">11.86</td><td width="64">0.18</td></tr>
<tr><td width="64">90</td><td width="64">15.14</td><td width="64">0.09</td><td width="64">14.50</td><td width="64">0.09</td><td width="64">14.82</td><td width="64">0.09</td><td width="64">13.31</td><td width="64">0.14</td></tr>
</tbody></table>
<br />
<div>
Model shows 0-30 MPH time of 2.98 seconds, pretty close to Bolt's advertised time. Does this mean model's 0-60 MPH time of 6.75 seconds will be about 6.7 seconds? Maybe, maybe not. I'll be very surprised if it turns out that way. That might be the day I buy some lottery tickets.</div>
<div>
<br /></div>
<div>
<b>Tangent thoughts: more gears</b></div>
<div>
<br /></div>
<div>
This blog post was re-written countless times. I started with simple analysis, which turned into dozens of plots, and into tangents like trying to find the gear ratio that will maximize 0-60 MPH time. Of course, gear change is not possible, so much of that was meaningless; they were just out of curiosity. While I won't clutter this blog post with all other tangents, I will add peak acceleration gear ratios. Who knows? Some lunatic may replace the gearbox to have quicker 0-60 MPH time, or maybe even have 3 speed massless gearbox.</div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjQ9ok4m0zAD-tFYx5TsTqayauC7N8I9MVZqoRor88-89AuIk_yE7XweCn-u4IwwUJwIlTFQbnn3l8lelgGvtyozC6VkQEOX3RZBEKVfmtw3EpmcZrKxCim-ZQxteyGYsL1AHkfmIJJEl3Z/s1600/10+best+gear+ratio.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjQ9ok4m0zAD-tFYx5TsTqayauC7N8I9MVZqoRor88-89AuIk_yE7XweCn-u4IwwUJwIlTFQbnn3l8lelgGvtyozC6VkQEOX3RZBEKVfmtw3EpmcZrKxCim-ZQxteyGYsL1AHkfmIJJEl3Z/s1600/10+best+gear+ratio.gif" /></a></div>
<div>
<div>
<br /></div>
<div>
We know the stock acceleration is based on top speed of 90 MPH. Then to achieve quicker acceleration, one must reduce the peak speed. Above plots' abscissa shows peak speed with gearing from 90 MPH. Essentially, 31 MPH is bit over 1/3 ratio, 62 MPH is bit over 2/3. With those gear changes, 0-30 MPH can be about 1.56 seconds, 0-60 MPH can be about 6.57 seconds.</div>
<div>
<br /></div>
<div>
Those are some quick times, rivaling BMW i3 and maybe even Bolt, but the top speed would be impractical. It's too bad SparkEV doesn't have 3 speed transmission. But then again, the tires squeal even with current level of acceleration, and even higher acceleration may not achieve much quicker times.</div>
<div>
<br /></div>
<div>
<div>
Something one can try is to see what would be the absolute maximum speed with changing the gear ratio. Recall above plot that SparkEV can barely make 103 MPH with current gearing. With gear change to move the torque curve to higher speed and sacrificing acceleration, what gear ratio would allow the highest possible speed? Homework for the reader!</div>
<div>
<br />
<b>Edit: 2016-10-20</b><br />
<br />
While browsing youtube, I came across an excellent episode by Engineering Explained about front wheel drive cars. He uses an example of 50-50 weight distribution car with low center of mass and short wheel base to analyze the maximum acceleration of a car that has tires with coefficient of friction of 1. That seems to describe SparkEV, except for the tires' coefficient of friction.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<iframe allowfullscreen="" class="YOUTUBE-iframe-video" data-thumbnail-src="https://i.ytimg.com/vi/dM5_rOKpnBw/0.jpg" frameborder="0" height="266" src="https://www.youtube.com/embed/dM5_rOKpnBw?feature=player_embedded" width="320"></iframe></div>
<br />
<br />
In the episode, the conclusion is that such car would have peak acceleration of about 0.4g. And what do you know? That's about the peak acceleration of SparkEV! And as anyone who drive SparkEV could tell you, stomping on the throttle regularly kicks in the traction control. So it seems SparkEV power is tuned for what is possible for "typical" tires, and no more. Unless torque can be increased above 30 MPH, times shown in this blog post are close to the maximum one could get with SparkEV, even with different gearing.<br />
<br /></div>
</div>
<div>
<b>Comparisons to other cars</b></div>
</div>
<div>
<div>
<br /></div>
<div>
Now that the model data validates experimental data to some degree, let's compare to some other cars. Insideevs has nice compilation of various EV performance.</div>
</div>
<div>
<br /></div>
<table border="1">
<tbody>
<tr bgcolor="#C0C0C0"><td width="128">Model</td><td width="32">0-30</td><td width="32">0-60</td><td width="32">30-60</td><td width="32">Source 30-60</td></tr>
<tr><td width="128">Tesla Model S P85</td><td width="32">1.7</td><td width="32">4.2</td><td width="32">2.5</td><td width="32">Insideevs(1) (Tesla Motors)</td></tr>
<tr><td width="128">Tesla Model S 85 base</td><td width="32">2.7</td><td width="32">5.6</td><td width="32">2.9</td><td width="32">Insideevs(2) (Consumer reports)</td></tr>
<tr><td width="128">BMW i3 (BEV version)</td><td width="32">2.9</td><td width="32">6.6</td><td width="32">3.7</td><td width="32">Insideevs(1) Edmunds</td></tr>
<tr><td width="128">V6 Camaro 323 HP</td><td width="32">2.6</td><td width="32">6.6</td><td width="32">4</td><td width="32">Insideevs(2) (Consumer reports)</td></tr>
<tr><td width="128">SparkEV 2014</td><td width="32">3.4</td><td width="32">7.6</td><td width="32">4.2</td><td width="32">model</td></tr>
<tr><td width="128">SparkEV 2015</td><td width="32">3.2</td><td width="32">7.4</td><td width="32">4.2</td><td width="32">model</td></tr>
<tr><td width="128">BMW i3 Rex</td><td width="32">3.3</td><td width="32">7.5</td><td width="32">4.2</td><td width="32">Insideevs(2) (Consumer reports)</td></tr>
<tr><td width="128">SparkEV 2014</td><td width="32"></td><td width="32"></td><td width="32">4.7</td><td width="32">Insideevs(1)</td></tr>
<tr><td width="128">SparkEV 2014</td><td width="32">3.1</td><td width="32">8</td><td width="32">4.9</td><td width="32">Insideevs(3)</td></tr>
<tr><td width="128">Honda Fit</td><td width="32"></td><td width="32"></td><td width="32">5.4</td><td width="32">Insideevs(1)</td></tr>
<tr><td width="128">2011 Volt</td><td width="32"></td><td width="32"></td><td width="32">5.8</td><td width="32">Insideevs(1)</td></tr>
<tr><td width="128">Fiat 500e</td><td width="32"></td><td width="32"></td><td width="32">5.9</td><td width="32">Insideevs(1)</td></tr>
<tr><td width="128">FocusEV</td><td width="32"></td><td width="32"></td><td width="32">6.1</td><td width="32">Insideevs(1)</td></tr>
<tr><td width="128">SmartED</td><td width="32"></td><td width="32"></td><td width="32">6.7</td><td width="32">Insideevs(1)</td></tr>
<tr><td width="128">LEAF</td><td width="32"></td><td width="32"></td><td width="32">6.8</td><td width="32">Insideevs(1)</td></tr>
<tr><td width="128">imiev</td><td width="32"></td><td width="32"></td><td width="32">10.6</td><td width="32">Insideevs(1)</td></tr>
<tr><td width="128">Cmax</td><td width="32"></td><td width="32"></td><td width="32">11</td><td width="32">Insideevs(1)</td></tr>
<tr><td width="128">2016 Volt</td><td width="32"></td><td width="32"></td><td width="32"></td><td width="32">Insideevs(4)</td></tr>
</tbody></table>
<br />
Insideevs(1)=<a href="http://insideevs.com/plug-vehicle-cross-section-acceleration-30-mph-60-mph-ev-mode">http://insideevs.com/plug-vehicle-cross-section-acceleration-30-mph-60-mph-ev-mode</a><br />
Insideevs(2)=comments in <a href="http://insideevs.com/plug-vehicle-cross-section-acceleration-30-mph-60-mph-ev-mode">http://insideevs.com/plug-vehicle-cross-section-acceleration-30-mph-60-mph-ev-mode</a><br />
Insideevs(3)=<a href="http://insideevs.com/whats-the-difference-0-30-mph-chevrolet-spark-ev-vs-nissan-leaf-videos">http://insideevs.com/whats-the-difference-0-30-mph-chevrolet-spark-ev-vs-nissan-leaf-videos</a><br />
Insideevs(4)=2016 Volt stat<br />
<br />
SparkEV is 1.4 seconds quicker to 60 MPH than the next on the list, Honda FitEV that's been discontinued for years. SparkEV even rivals BMW i3 REx that cost double and incorporate carbon fiber in its body. SparkEV even comes close to 323 HP V6 Camaro in 30-60 MPH acceleration. This is from a $16K subcompact city car. That is just WOW!<br />
<br />
<b>Conclusion of results</b><br />
<br />
Using a model based on torque curve, I showed that 2014 experimental data roughly matches the model data. Using the model, I showed that Chevy's claim of 0-60 MPH in 7.2 second for 2015 is plausible, though bit optimistic. I explored hill climbing ability and showed that 90 MPH is close to the maximum speed of the car even without electronic speed limiting.<br />
<br />
<b>How they're made</b><br />
<br />
Once again, we go to the sausage factory to see the meat grinder doing the work. As before, Octave is used.<br />
<br />
Following parameters are needed:<br />
<br />
1. Lots of free time to read sparsely commented code<br />
2. Freeware GNU Octave (Matlab may not work due to plotyy function)<br />
3. Experimental data from various sources<br />
4. Motor torque characteristics plot<br />
5. Drag force for various speeds and weight<br />
6. Other data such as gear ratio, tire diameter, etc.<br />
<br />
<b>Motor torque characteristics plot</b><br />
<br />
The essense of the model is torque available at the wheels at various speeds. Combined with the tire diameter, we can find the force that's pushing the car. Such data is available in graph form.<br />
<div>
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgLOVDaruEdmXj41QY5ibrEtBrdv7PPyas1KlHKVcnnHE7wjWquV5E4NQiCjsdoOepGG2VnqZimLmc6tenWSDF6R_ubdJA-kf1OLuaPe7KeOIztKIUuAOZdXYrKWKtFdRYSuJqcPu3aDOQC/s1600/2014_sparkev_torque_curve.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="491" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgLOVDaruEdmXj41QY5ibrEtBrdv7PPyas1KlHKVcnnHE7wjWquV5E4NQiCjsdoOepGG2VnqZimLmc6tenWSDF6R_ubdJA-kf1OLuaPe7KeOIztKIUuAOZdXYrKWKtFdRYSuJqcPu3aDOQC/s640/2014_sparkev_torque_curve.jpg" width="640" /></a></div>
<br />
I don't know where this plot came from, but from the looks of it, it probably came from Chevy. Are we to trust it? Well, if the model fits experimental data from other sources, it's probably good. Combined with drag data from ecomodder web site, we can make a model of the car's performance.<br />
<br />
First thing to do is to extract numbers from torque curve graph. One can do this manually by relating pixel locations to axis. Fortunately, there are tools that allow you to do this without manually finding pixels. An excellent tool is called "WebPlotDigitizer" that works in web browser.<br />
<br />
<a href="http://arohatgi.info/WebPlotDigitizer/app/?">http://arohatgi.info/WebPlotDigitizer/app/?</a><br />
<br />
Then we get these data points.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhvZ8Yn7azuFWy-U6AXK_-tCTOM3jpzgP_kjoDcXRsNT4so5YAyYW7kIX-jW4Y7x59D8eCzz6OeOoxmfYdNn929EcRktL0WIK6L0J_ssnZsoXtegjt199kGW82PueXZTaEJ-NR8ySTSvtBr/s1600/2014_sparkev_torque_curve_dotted.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhvZ8Yn7azuFWy-U6AXK_-tCTOM3jpzgP_kjoDcXRsNT4so5YAyYW7kIX-jW4Y7x59D8eCzz6OeOoxmfYdNn929EcRktL0WIK6L0J_ssnZsoXtegjt199kGW82PueXZTaEJ-NR8ySTSvtBr/s1600/2014_sparkev_torque_curve_dotted.gif" /></a></div>
<br />
The data from the graph is not quite correct since the graph could be based on top of the "dot", middle, bottom, or anywhere in between. What we do is to correct the torque values based on known data. We know the peak torque on 2014 is 400 ft-lb at the motor with 3.17 reduction gear ratio. 2016 data is obtained from Chevy web site.<br />
<br />
<a href="http://media.chevrolet.com/media/us/en/chevrolet/vehicles/spark-ev/2016.html">http://media.chevrolet.com/media/us/en/chevrolet/vehicles/spark-ev/2016.html</a><br />
<br />
Torque is 327 ft-lb at the motor with 3.87 reduction gear ratio. Doing the math shows 1268 ft-lb for 2014 vs 1266 ft-lb for 2016 (note: above plot is N-m, not ft-lb), close enough to say that rear wheel torque are the same. Power is rated to be 105 kW (140 HP), but I recall some older publications showed 103 kW (137 HP). Let's stick to 105 kW.<br />
<br />
Torque data from the graph is first scaled to match this peak torque number, and power at the wheels is computed. Then we "stretch" the speed corresponding to torque until this peak power is achieved. Resulting data would have 400 ft-lb peak with 3.17 gearing and 105 kW (140 HP) peak.<br />
<br />
Below are plots with just torque scaling (uncorrected) and power correction (corrected). Peak power occurs at 45 MPH. Assuming power out of the battery is 120 kW, it would be almost 88% efficient. Where did I get 120 kW? That's the maximum number I saw on display while hard accelerating up a hill.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj9yGAYU7NZpxLLIblMU3v-0rmoxx-geRF7ZVkVBKKzODYKmvzMkmxZs29i5BuAlGQbYWvTHgqbd8PzVE6ZKz5-mHG3BGvi1llZ3uWgbp-j7Mo3GS7Tf84NGnpbm6EulPPNiFykx5M-ciL6/s1600/01+power.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj9yGAYU7NZpxLLIblMU3v-0rmoxx-geRF7ZVkVBKKzODYKmvzMkmxZs29i5BuAlGQbYWvTHgqbd8PzVE6ZKz5-mHG3BGvi1llZ3uWgbp-j7Mo3GS7Tf84NGnpbm6EulPPNiFykx5M-ciL6/s1600/01+power.gif" /></a></div>
<br />
A word of caution on efficiency. It is only with regard to fully stepping down on the accelerator, a worst case scenario. If the accelerator is only partially depressed, it is unknown what the efficiency would be. It may not scale linearly and most likely, it would be much higher, though the exact number is impossible to know without experiments. Still, be gentle with the accelerator if you want to conserve energy.<br />
<br />
Something that's not clear is if the torque values are from braking horsepower (BHP) or if it's taken while accelerating. The distinction is important, because acceleration would result in angular acceleration of rotating parts (motor, gears, wheels) eating into the torque budget. Since the model seems to match the experimental data, we assume the torque figure takes into account the angular acceleration of rotating parts.<br />
<br />
Then the question is how quick was the angular acceleration when measured? Using the most powerful engineering tool in the universe as described in the The hitchhiker's guide to the galaxy, SEP (someone else's problem)!<br />
<br />
<b>Dyno for everyone!</b><br />
<br />
A side thought: a poor man's dyno can be made by simply measuring the angular acceleration of the tires at full throttle while the car is on jacks. One can use cheap optical sensors with strips of aluminum tape from dollar store taped to tires and microcontroller to measure the angular acceleration as the throttle is fully stomped on. Due to differential gear, it may need some tweaks, but it could be a way to measure dynamic torque / horsepower of the car very cheaply, albeit dangerously. Moment of inertia of the wheels/tires is easy to measure with standard apple (the fruit, not the computer/phone) and some strings. It would only take seconds to measure the torque / power. Ok, now back to SparkEV.<br />
<br />
<b>Drag force for various speeds and weight</b><br />
<br />
Drag forces for various speeds are found by using ecomodder web site. The weight and aerodynamic parameters are from "reputable sources" (haha!), and drag only depend on them as opposed to power that also depend on motor efficiency. The drag values should be pretty close to actual.<br />
<br />
Driver weight is assumed to be 150 lb. Below is the case for 2014 model year.<br />
<br />
<a href="http://ecomodder.com/forum/tool-aero-rolling-resistance.php?Weight=3139&WeightUnits=lbs&CRR=.01&Cd=.326&FrontalArea=27&FrontalAreaUnits=ft^2&FuelWh=33557&IceEfficiency=.9&DrivetrainEfficiency=.95&ParasiticOverhead=500&rho=1.225&FromToStep=5-200-5">http://ecomodder.com/forum/tool-aero-rolling-resistance.php?Weight=3139&WeightUnits=lbs&CRR=.01&Cd=.326&FrontalArea=27&FrontalAreaUnits=ft^2&FuelWh=33557&IceEfficiency=.9&DrivetrainEfficiency=.95&ParasiticOverhead=500&rho=1.225&FromToStep=5-200-5</a><br />
<br />
Below is to get drag data for 2015 model year by simply changing the weight.<br />
<br />
<a href="http://ecomodder.com/forum/tool-aero-rolling-resistance.php?Weight=3016&WeightUnits=lbs&CRR=.01&Cd=.326&FrontalArea=27&FrontalAreaUnits=ft^2&FuelWh=33557&IceEfficiency=.9&DrivetrainEfficiency=.95&ParasiticOverhead=500&rho=1.225&FromToStep=5-200-5">http://ecomodder.com/forum/tool-aero-rolling-resistance.php?Weight=3016&WeightUnits=lbs&CRR=.01&Cd=.326&FrontalArea=27&FrontalAreaUnits=ft^2&FuelWh=33557&IceEfficiency=.9&DrivetrainEfficiency=.95&ParasiticOverhead=500&rho=1.225&FromToStep=5-200-5</a><br />
<br />
Below is to get drag data for GVWR (3761 lb)<br />
<br />
<a href="http://ecomodder.com/forum/tool-aero-rolling-resistance.php?Weight=3761&WeightUnits=lbs&CRR=.01&Cd=.326&FrontalArea=27&FrontalAreaUnits=ft^2&FuelWh=33557&IceEfficiency=.9&DrivetrainEfficiency=.95&ParasiticOverhead=500&rho=1.225&FromToStep=5-200-5">http://ecomodder.com/forum/tool-aero-rolling-resistance.php?Weight=3761&WeightUnits=lbs&CRR=.01&Cd=.326&FrontalArea=27&FrontalAreaUnits=ft^2&FuelWh=33557&IceEfficiency=.9&DrivetrainEfficiency=.95&ParasiticOverhead=500&rho=1.225&FromToStep=5-200-5</a><br />
<br />
One thing to note is that Webplotdigitizer spits out 80 data points while ecomodder spits out 19 data points. To reconcile, I again use polynomial on drag data. Since drag force data is determined by running a math model at ecomodder web site, I'm basically reversing that process by using second order polynomial (recall power is third order, then force is second order). Then I plug in 80 speed parameters to the polynomial, and it will be accurate to any speed. In essence, it's interpolation with 100% accuracy at any speed! (yeah, sure).<br />
<br />
<b>Other data</b><br />
<br />
Tire diameter for 185/55R15 tires is found from <a href="https://tiresize.com/chart">https://tiresize.com/chart</a> as 23 inches.<br />
<br />
All the others can be found in Chevy web site or various google searches.<br />
<br />
<b>Appendix</b><br />
<br />
I can go through the code and explain each line, but this blog post is running way too long as is. Besides, I think the code is entirely self explanatory, no further comment needed (the famous last words before software engineer getting fired)! So without further delay, below is the m-file for you to try out in Octave.<br />
<div>
<br /></div>
<div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">close all; clear;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">global fname; fname = 'acceleration.csv';</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">dlmwrite(fname, '');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% parameters from torque graph</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">speed_mph =[0.00 0.89 2.17 3.35 4.53 5.71 6.89 8.07 9.25 10.43 11.61 ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> 12.79 13.96 15.14 16.32 17.50 18.68 19.86 21.04 22.22 ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> 23.40 24.58 25.76 26.94 28.12 29.29 30.47 31.65 32.83 ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> 34.01 35.19 36.37 37.55 38.73 39.94 41.09 42.27 43.45 ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> 44.30 45.28 46.32 47.30 48.27 49.23 50.25 51.38 52.56 ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> 53.74 54.92 56.09 57.27 58.45 59.63 60.81 61.99 63.17 ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> 64.35 65.53 66.71 67.89 69.07 70.25 71.42 72.60 73.78 ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> 74.96 76.14 77.32 78.50 79.68 80.86 82.04 83.22 84.40 ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> 85.58 86.54 87.49 88.38 89.36 90];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">torque_nm =[1630 1631 1718 1724 1717 1715 1715 1715 1715 1715 1715 ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> 1715 1715 1715 1715 1715 1715 1715 1715 1715 1715 1715 ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> 1715 1717 1722 1723 1719 1710 1701 1691 1681 1668 1654 ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> 1639 1615 1595 1565 1530 1494 1457 1418 1378 1340 1303 ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> 1265 1234 1199 1166 1134 1104 1075 1047 1021 995.4 970.5 ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> 946.5 924.3 902.4 882.3 862.9 844.6 826.8 809.8 792.9 ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> 777.3 764.2 752.6 741.9 731.3 720.1 706.7 690.4 669.3 ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> 640.0 602.8 558.9 519.9 480.4 443.2 411.2];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% SparkEV gear ratios</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">gear_ratio_2014 = 3.17;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">gear_ratio_2015 = 3.87;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% maximum power displayed when accelerating hard on steep slope</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">global battery_power_kw; battery_power_kw = 120;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">motor_power_kw = 105;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% stock tire diameter of 185/55R15</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">tire_ft = 23/12/2; </span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% drag force data from ecomooder</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">global speed_mph_integer; speed_mph_integer = 0:5:90;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% mass is always assumed with 150 lb driver</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">mass_2014_lb = 2989 + 150;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">mass_2015_lb = 2866 + 150;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">mass_gvwr_lb = 3761;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% drag values from ecomodder web site in newtons</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">drag_2014_n = [142.13 142.13 149.64 162.15 179.67 202.19 229.71 ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> 262.25 299.78 342.32 389.87 442.42 499.97 562.53 ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> 630.09 702.66 780.23 862.81 950.4];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">drag_2015_n = [136.66 136.66 144.17 156.68 174.2 196.72 224.24 ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> 256.77 294.31 336.85 384.39 436.94 494.5 557.06 ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> 624.62 697.19 774.76 857.34 944.92];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">drag_gvwr_n = [169.8 169.8 177.31 189.82 207.34 229.86 257.38 ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> 289.91 327.45 369.99 417.53 470.08 527.64 590.2 ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> 657.76 730.33 807.9 890.48 978.06];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% some conversion factors</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">global feet_in_mile; global rpm_ftlb_to_hp; global hp_to_kw;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">feet_in_mile = 5280; rpm_ftlb_to_hp = 5252; hp_to_kw = 0.7457;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">nm_to_ftlb = 0.737562149;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">newton_to_pound = 0.224809;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">torque_ftlb = torque_nm * nm_to_ftlb;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">driveforce_lb = torque_ftlb / tire_ft;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% polynomial for drag force so we can interpolate for higher speeds.</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">drag_2014_lb_poly = polyfit(speed_mph_integer, ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> drag_2014_n * newton_to_pound, 2);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">drag_2015_lb_poly = polyfit(speed_mph_integer, ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> drag_2015_n * newton_to_pound, 2);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">drag_gvwr_lb_poly = polyfit(speed_mph_integer, ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> drag_gvwr_n * newton_to_pound, 2);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% Functions to write to file</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">global csv_head; global csv_data;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">csv_head = cellstr('speed (mph)');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">csv_data = speed_mph_integer';</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">function fwrite_text(data)</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> global fname;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> fid=fopen(fname,'at');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> fprintf(fid, data);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> fclose(fid);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">endfunction</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">function csv_data_append(header, speed_mph, data_raw)</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> global speed_mph_integer; global csv_head; global csv_data;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> csv_head = [csv_head cellstr(header)];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> data = interp1(speed_mph, data_raw, speed_mph_integer)';</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> csv_data = [csv_data data];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">endfunction</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">function csv_file_write(fname)</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> global speed_mph_integer; global csv_head; global csv_data;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> fid=fopen(fname,'at');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> [rows,cols]=size(csv_head);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> for i=1:rows</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> fprintf(fid,'%s,',csv_head{i,1:end-1})</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> fprintf(fid,'%s\n',csv_head{i,end})</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> end</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> fclose(fid);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> dlmwrite(fname, csv_data, '-append');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> csv_head = cellstr('speed (mph)');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> csv_data = speed_mph_integer';</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">endfunction</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% octave plotyy has a bug as well as not recommended for Matlab</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">function [ax, h1, h2] = myplotyy(x, y1, y2, alegend, alocation)</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> % global EXECUTABLE</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> % if EXECUTABLE==MATLAB</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> % yyaxis or some such</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> % else % OCTAVE</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> % Octave has problem with legend and data order with plotyy</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> [ax,h1,h2]=plotyy( x, y1, x, y2 );</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> legend(fliplr(alegend)', 'location', alocation);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> set(h2, {'Color'},get(h1,'Color'));</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> % end</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">endfunction</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% find peak power and make minor adjustment to data to match spec</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">function [tire_power_kw,efficiency_pct] = ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> compute_power(atitle, speed_mph, tire_ft, torque_ftlb)</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> global feet_in_mile; global rpm_ftlb_to_hp; global hp_to_kw;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> global battery_power_kw;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> tire_rpm = speed_mph * feet_in_mile / 60 / (2 * pi * tire_ft);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> tire_power_kw = torque_ftlb .* tire_rpm / rpm_ftlb_to_hp * hp_to_kw;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> efficiency_pct = tire_power_kw / battery_power_kw * 100;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> csv_data_append([atitle ' tire power (kW)'], speed_mph, tire_power_kw);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> csv_data_append([atitle ' efficiency (%)'], speed_mph, efficiency_pct);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">endfunction</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">function plot_power(legend_2, speed_mph, tire_power_kw_2, efficiency_pct_2)</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> global battery_power_kw;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> figure;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> [ax,h1,h2]=myplotyy(speed_mph, tire_power_kw_2, efficiency_pct_2, ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> legend_2, 'east');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> ylabel(ax(2), 'efficiency (%)'); ylabel(ax(1), 'power (kW)');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> axis(ax(2), [0 90 0 100]); axis(ax(1), [0 90 0 battery_power_kw]);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> set(ax(2), 'ytick', 0:10:100); set(ax(1), 'ytick', 0:12:battery_power_kw);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> grid on; xlabel('speed (mph)'); set(ax(1), 'xtick', 0:10:90);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> title('Power efficiency at peak torque');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> nn=2; %was for loop, but too messy</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> peak_eff = max(efficiency_pct_2(:,nn));</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> peak_eff_speed = speed_mph( efficiency_pct_2(:,nn) == peak_eff );</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> peak_power = max(tire_power_kw_2(:,nn));</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> hold on;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> plot(peak_eff_speed:peak_eff_speed, 0:battery_power_kw, 'r-');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> hold off;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> text(peak_eff_speed+1, peak_power+1, ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> [num2str(round(peak_eff_speed*10)/10) ' mph, ' ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> num2str(round(peak_eff*10)/10) '%, ' ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> num2str(round(peak_power*10)/10) ' kW']);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">endfunction</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">fwrite_text('SparkEV power and efficiency\n');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% we know 2014 torque at 400 ft-lb and gear ratio. adjust torque so that</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% peak torque matches specified data.</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">correction_torque = (400*gear_ratio_2014) / max(torque_ftlb);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">torque_nm = torque_nm * correction_torque;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">torque_ftlb = torque_ftlb * correction_torque;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">driveforce_lb = driveforce_lb * correction_torque;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% find power with new torque value; peak power may not match, so uncorrected</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">atitle = 'uncorrected';</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">[tire_power_kw,efficiency_pct] = ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> compute_power(atitle, speed_mph, tire_ft, torque_ftlb);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">tire_power_kw_2 = tire_power_kw';</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">efficiency_pct_2 = efficiency_pct';</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">legend_2 = cellstr(atitle);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% Chevy specifies peak power of 105 kW. Expand speed to achieve that.</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% It should also match 60 kW at 90MPH shown in power curve.</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">correction_power = motor_power_kw / max(tire_power_kw);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">speed_mph = speed_mph * correction_power;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">atitle = 'corrected';</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">[tire_power_kw,efficiency_pct] = ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> compute_power(atitle, speed_mph, tire_ft, torque_ftlb);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">tire_power_kw_2 = [tire_power_kw_2 tire_power_kw'];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">efficiency_pct_2 = [efficiency_pct_2 efficiency_pct'];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">legend_2 = [legend_2 cellstr(atitle)];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">plot_power(legend_2, speed_mph, tire_power_kw_2, efficiency_pct_2);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">csv_file_write(fname);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% Function to find drag force for different weights</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% In absense of full formula to find drag, we have to figure out how to compute</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% various drag force for different weights rather than running ecomodder</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% website each time. It seems drag polynomial coefficient for lowest order</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% changes for various weights at 1% (rolling resistance). That's totally</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% expected. Therefore, it's simply replacing lowest order coefficient with</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% 1% of mass to find new drag.</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">function drag_force_lb = find_drag(drag_lb_poly, mass_lb, speed_mph)</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> % finds new drag force for any mass</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> drag_poly = drag_lb_poly;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> drag_poly(3) = mass_lb * 0.01;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> drag_force_lb = polyval(drag_poly, speed_mph);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">endfunction</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% Function to find acceleration times, gforce, distance traveled. Note that </span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% time for speed is different from distance traveled</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">function [time_sec, gforce, time_dist_sec, dist_miles] = ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> find_time_dist(driveforce_lb, mass_lb, drag_lb, speed_mph)</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> ft_per_sec_to_mph = 1.4666667;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> gravity_ft_sec_sec = 32.2;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> % find gforce and speed over time</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> gforce = (driveforce_lb-drag_lb) ./ (mass_lb);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> acc_mph_per_sec = gforce * gravity_ft_sec_sec / ft_per_sec_to_mph;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> speed_delta_mph = [0 ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> (speed_mph(2:length(speed_mph)) - speed_mph(1:length(speed_mph)-1))];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> time_delta_sec = speed_delta_mph ./ acc_mph_per_sec;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> time_sec = cumsum(time_delta_sec);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> % find distance over time</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> speed_extend_mph = [speed_mph ones(1, 1000)*max(speed_mph)];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> time_delta_extend_sec = [time_delta_sec ones(1, 1000)*0.1];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> distance_delta_miles = (speed_extend_mph/3600) .* time_delta_extend_sec;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> time_dist_sec = cumsum(time_delta_extend_sec);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> dist_miles = cumsum(distance_delta_miles);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">endfunction</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% function to compute and plot single car data</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">function plot_one_car(car_name, mass_base_lb, drag_base_lb_poly, speed_mph, ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> driveforce_lb)</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> time_sec_2=[]; gforce_2=[]; time_dist_sec_2=[]; dist_miles_2=[];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> legend_2 = [];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> for nn=1:4</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> if nn==1</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> atitle = car_name; mass_lb = mass_base_lb;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> elseif nn==2</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> atitle = [car_name ' no driver']; mass_lb = mass_base_lb - 150;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> elseif nn==3</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> atitle = [car_name ' 75lb driver']; mass_lb = mass_base_lb - 75;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> elseif nn==4</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> atitle = [car_name ' no drag']; mass_lb = mass_base_lb;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> drag_base_lb_poly = zeros(1, length(drag_base_lb_poly));</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> end</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> drag_lb = find_drag(drag_base_lb_poly, mass_lb, speed_mph);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> [time_sec, gforce, time_dist_sec, dist_miles] = ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> find_time_dist(driveforce_lb, mass_lb, drag_lb, speed_mph);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> csv_data_append([atitle ' time (sec)'], speed_mph, time_sec);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> csv_data_append([atitle ' gforce'], speed_mph, gforce);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> </span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> if (nn==1)</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> legend_2 = cellstr(atitle);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> else</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> legend_2 = [legend_2 cellstr(atitle)];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> end</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> time_sec_2 = [time_sec_2 time_sec'];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> gforce_2 = [gforce_2 gforce'];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> time_dist_sec_2 = [time_dist_sec_2 time_dist_sec'];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> dist_miles_2 = [dist_miles_2 dist_miles'];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> end</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> figure; </span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> [ax,h1,h2]=myplotyy(time_sec_2, gforce_2, speed_mph', legend_2, 'east');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> xlabel('time (sec)'); set(gca, 'xtick', 0:1:10);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> ylabel(ax(2), 'speed (mph)'); ylabel (ax(1), 'g force');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> miny=.15; maxy=.5;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> axis(ax(2), [0 10 0 70]); axis(ax(1), [0 10 miny maxy]); grid on;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> set(ax(2), 'ytick', 0:10:70); set(ax(1), 'ytick', miny:(maxy-miny)/7:maxy);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> title([car_name ' acceleration speed vs time']);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> max_x = 20;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> figure; plot(time_dist_sec_2, dist_miles_2);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> xlabel('time (sec)'); ylabel('distance (miles)');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> axis([0 max_x 0 0.3]); grid on;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> set(gca, 'xtick', 0:max_x); set(gca, 'ytick', 0:0.025:0.3);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> title([car_name ' acceleration distance vs time']);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> legend(legend_2, 'location', 'east');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">endfunction</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% find data for 2014</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">plot_one_car('2014', mass_2014_lb, drag_2014_lb_poly, speed_mph, driveforce_lb);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">csv_file_write(fname);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% run data for all mass, from -1000 lb to +700 lb based on 2015 mass</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% function to plot acceleration for various weights</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">function plot_acc_over_weights(atitle, speed_mph, mass_min_lb, mass_max_lb, ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> drag_base_lb_poly, driveforce_lb)</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> mass_lb_2=[]; time_sec_2=[]; gforce_2=[]; time_dist_sec_2=[]; dist_miles_2=[];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> for mass_lb=[mass_min_lb:100:mass_max_lb]</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> drag_lb = find_drag(drag_base_lb_poly, mass_lb, speed_mph);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> [time_sec, gforce, time_dist_sec, dist_miles] = ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> find_time_dist(driveforce_lb, mass_lb, drag_lb, speed_mph);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> mass_lb_2 = [mass_lb_2 mass_lb];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> time_sec_2 = [time_sec_2 time_sec'];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> gforce_2 = [gforce_2 gforce'];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> time_dist_sec_2 = [time_dist_sec_2 time_dist_sec'];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> dist_miles_2 = [dist_miles_2 dist_miles'];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> csv_data_append([num2str(mass_lb) 'lb time (sec)'], speed_mph, time_sec);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> csv_data_append([num2str(mass_lb) 'lb gforce'], speed_mph, gforce);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> end</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> figure; </span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> [ax,h1,h2]=myplotyy(time_sec_2, gforce_2, speed_mph', ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> cellstr(num2str(mass_lb_2'))', 'east');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> grid on; xlabel('time (sec)'); set(gca, 'xtick', 0:1:10);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> ylabel(ax(2), 'speed (mph)'); ylabel (ax(1), 'g force');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> if mass_min_lb > 3000</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> axis(ax(2), [0 10 0 70]); set(ax(2), 'ytick', 0:10:70);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> miny=0.15; maxy=0.5; divy=7;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> else</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> axis(ax(2), [0 10 0 90]); set(ax(2), 'ytick', 0:10:90);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> miny=.15; maxy=0.69; divy=9;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> end</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> axis(ax(1), [0 10 miny maxy]);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> set(ax(1), 'ytick',miny:((maxy-miny)/divy):maxy);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> title(atitle);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">endfunction</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">atitle = '2015 SparkEV acceleration for weight gain speed vs time';</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">plot_acc_over_weights(atitle, ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> speed_mph, mass_2015_lb, mass_2015_lb+700, ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> drag_2015_lb_poly, driveforce_lb);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">fwrite_text([atitle '\n']); csv_file_write(fname);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">atitle = '2015 SparkEV acceleration for weight reduction speed vs time';</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">plot_acc_over_weights(atitle, ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> speed_mph, mass_2015_lb-1000, mass_2015_lb-100, ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> drag_2015_lb_poly, driveforce_lb);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">fwrite_text([atitle '\n']); csv_file_write(fname);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% acceleration over hills</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">function plot_hill_acceleration(atitle, speed_mph, mass_lb, ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> drag_base_lb_poly, driveforce_lb)</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> grade_pct_2=[];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> time_sec_2=[]; gforce_2=[]; time_dist_sec_2=[]; dist_miles_2=[];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> for grade_pct=[0 1 2 3 5 8 13 21]</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> hill_angle = atan(grade_pct/100);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> mass_normal = mass_lb * cos(hill_angle);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> drag_lb = find_drag(drag_base_lb_poly, mass_normal, speed_mph);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> hill_driveforce_lb = driveforce_lb - mass_lb * sin(hill_angle);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> [time_sec, gforce, time_dist_sec, dist_miles] = ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> find_time_dist(hill_driveforce_lb, mass_lb, drag_lb, speed_mph);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> %zero out negative values due to too steep hill</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> time_sec(gforce<0) = 1000; gforce(gforce<0) = 0;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> time_sec(time_sec<0) = 1000; gforce(time_sec<0) = 0;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> grade_pct_2 = [grade_pct_2 grade_pct];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> time_sec_2=[time_sec_2 time_sec'];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> gforce_2=[gforce_2 gforce'];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> time_dist_sec_2=[time_dist_sec_2 time_dist_sec'];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> dist_miles_2=[dist_miles_2 dist_miles'];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> csv_data_append([num2str(grade_pct) '% grade time (sec)'], ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> speed_mph, time_sec);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> csv_data_append([num2str(grade_pct) '% grade gforce'], speed_mph, gforce);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> end</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> figure; </span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> [ax,h1,h2]=myplotyy(time_sec_2, gforce_2, speed_mph', ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> cellstr(num2str(grade_pct_2'))', 'east');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> xlabel('time (sec)'); set(gca, 'xtick', 0:2:20); grid on;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> ylabel(ax(2), 'speed (mph)'); ylabel (ax(1), 'g force');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> axis(ax(2), [0 20 0 70]); set(ax(2), 'ytick', 0:10:70);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> miny=0; maxy=0.49; divy=7;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> axis(ax(1), [0 20 miny maxy]);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> set(ax(1), 'ytick',miny:((maxy-miny)/divy):maxy);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> title(atitle);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">endfunction</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">atitle = '2015 SparkEV acceleration over % grades speed vs time';</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">plot_hill_acceleration(atitle, speed_mph, mass_2015_lb, ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> drag_2015_lb_poly, driveforce_lb);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">fwrite_text([atitle '\n']); csv_file_write(fname);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% climbing ability for various weights</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">function plot_climbing(atitle, speed_mph, mass_2015_lb, drag_base_lb_poly, ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> driveforce_lb)</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> mass_lb_2=[]; climb_pct_2=[];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> for mass_delta=[0:100:700]</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> mass_lb = mass_2015_lb+mass_delta;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> drag_lb = find_drag(drag_base_lb_poly, mass_lb, speed_mph);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> force_lb = driveforce_lb - drag_lb;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> climb_pct = tan(asin((force_lb)/(mass_lb))) * 100;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> %Chevy specifies max hill start as 25% at 0 MPH</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> climb_pct(1)=25;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> mass_lb_2 = [mass_lb_2; mass_lb];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> climb_pct_2 = [climb_pct_2 climb_pct'];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> csv_data_append([num2str(mass_lb) 'lb climb (%)'], speed_mph, climb_pct);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> end</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> figure; plot( speed_mph, climb_pct_2);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> xlabel('speed (mph)'); ylabel('grade (%)');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> axis([0 90 0 50]); grid on;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> set(gca, 'xtick', 0:5:90); set(gca, 'ytick', 0:5:50);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> title(atitle);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> legend(cellstr(num2str(mass_lb_2)), 'location', 'northeast');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">endfunction</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">atitle = '2015 SparkEV climbing ability vs speed over weight';</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">plot_climbing(atitle, speed_mph, mass_2015_lb, drag_2015_lb_poly, ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> driveforce_lb);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">fwrite_text([atitle '\n']); csv_file_write(fname);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% Bolt guess</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">bolt_peak_motor_torque_ftlb = 266;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">bolt_gear_ratio = 7.05;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">bolt_tire_radius_ft = 25.5 / 12 / 2;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">bolt_mass_lb = 3580 + 150;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">bolt_peak_power_kw = 150;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% find the speed at which Bolt's peak power will occur</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">bolt_rpm_to_mph = (2*pi*bolt_tire_radius_ft/feet_in_mile) / bolt_gear_ratio* 60;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">bolt_peak_motor_power_rpm = ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> rpm_ftlb_to_hp * bolt_peak_power_kw/hp_to_kw / bolt_peak_motor_torque_ftlb;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">bolt_peak_motor_power_mph = bolt_peak_motor_power_rpm * bolt_rpm_to_mph;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% SparkEV torque to Bolt by simply scaling</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">bolt_torque_ftlb = bolt_peak_motor_torque_ftlb * bolt_gear_ratio * ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> (torque_ftlb / max(torque_ftlb));</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">bolt_driveforce_lb = bolt_torque_ftlb / bolt_tire_radius_ft;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">plot_one_car('bolt', bolt_mass_lb, drag_2015_lb_poly, speed_mph, bolt_driveforce_lb);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">csv_file_write(fname);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% find quickest gear ratio for speeds by going through all ratios</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">function find_best_gear_ratio(drag_lb_poly, mass_lb, speed_mph, driveforce_lb)</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> time_max_30mph=[]; time_max_60mph=[];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> peak_speeds = 31:90;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> for peak_speed=peak_speeds</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> gear_ratio = peak_speed / 90;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> gear_driveforce_lb = driveforce_lb / gear_ratio;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> gear_speed_mph = speed_mph * gear_ratio;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> </span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> drag_lb = find_drag(drag_lb_poly, mass_lb, gear_speed_mph);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> [time_sec, gforce, time_dist_sec, dist_miles] = ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> find_time_dist(gear_driveforce_lb, mass_lb, drag_lb, gear_speed_mph);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> </span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> gear_int_speed_mph = 0:fix(max(gear_speed_mph));</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> gear_int_time_sec = interp1(gear_speed_mph, time_sec, gear_int_speed_mph);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> </span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> time_max_30mph = [time_max_30mph gear_int_time_sec(gear_int_speed_mph==30)];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> if (max(gear_int_speed_mph) < 60)</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> time_max_60mph = [time_max_60mph 0];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> else</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> time_max_60mph = [time_max_60mph gear_int_time_sec(gear_int_speed_mph==60)];</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> end</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> end</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> figure;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> subplot(2, 1, 1); plot(peak_speeds, time_max_30mph, 'o-');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> xlabel('peak speed (mph)'); ylabel('time (sec)');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> axis([31 37 1.55 1.63]); grid on;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> title('best peak speed gearing for 30 MPH acceleration');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> subplot(2, 1, 2); plot( peak_speeds, time_max_60mph, 'o-');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> xlabel('peak speed (mph)'); ylabel('time (sec)');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> axis([60 66 6.56 6.64]); grid on;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> title('best peak speed gearing for 60 MPH acceleration');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">endfunction</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">find_best_gear_ratio(drag_2015_lb_poly, mass_2015_lb, speed_mph, driveforce_lb)</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">% find theoretical maximum speed with gear change</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">function plot_maxspeed_with_gear_chage(speed_mph, driveforce_lb, drag_poly, ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> mass_lb)</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> ext_min_speed = 88; ext_max_speed=105; ext_plot_min_speed = 75;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> ext_speed_mph = ext_min_speed:ext_max_speed;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> ext_driveforce_poly = polyfit(speed_mph(speed_mph > ext_min_speed), ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> driveforce_lb(speed_mph > ext_min_speed), 1);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> ext_driveforce_lb = polyval(ext_driveforce_poly, ext_speed_mph);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> ext_drag_speed = ext_plot_min_speed:ext_max_speed;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> ext_drag_lb = find_drag(drag_poly, mass_lb, ext_drag_speed);</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> figure;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> plot(speed_mph(speed_mph > ext_plot_min_speed), </span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> driveforce_lb(speed_mph > ext_plot_min_speed), 'bo-');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> hold on;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> plot(ext_speed_mph, ext_driveforce_lb, 'go-');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> plot(ext_drag_speed, ext_drag_lb, 'ro-');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> hold off;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> xlabel('speed (mph)'); ylabel('force (lb)');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> axis([75 105 0 600]); grid on;</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> title('SparkEV theoretical peak speed');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> legend('drive force', 'extended drive force', 'drag force');</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">endfunction</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;">plot_maxspeed_with_gear_chage(speed_mph, driveforce_lb, drag_2015_lb_poly, ...</span></div>
<div>
<span style="font-family: "courier new" , "courier" , monospace;"> mass_2015_lb);</span></div>
</div>
<div>
<br /></div>
sparkevhttp://www.blogger.com/profile/04362518920979349841noreply@blogger.com11tag:blogger.com,1999:blog-6875771813122616391.post-48907300507427931702016-05-11T13:43:00.001-07:002016-05-21T08:46:59.833-07:00Regenerative braking efficiencyAs I drive along, I was always curious about regenerative braking efficiency. With Prius, there was small yellow tags on display to show 50 Wh (0.05 kWh) of energy regenerated. For a long down hill, I got multiple of these tags in any 5 minute window (Prius keeps track at 5 minute intervals). But the regeneration efficiency was always suspect. Prius regeneration is very weak, and brake pedal must be applied. Then how much of that is wasted as heat and how much to regen?<br />
<br />
On SparkEV, there is no indication of how much energy was regenerated. However, it shows Watts in power being used and regenerated. It also has strong regen in L mode such that one does not need to apply the brakes for many hills. This makes it a good platform for testing regen efficiency.<br />
<br />
<b>Hilly road</b><br />
<br />
My method is to take a hilly road of some length and drive down then up, both at same speed. Whatever regen power shown is compared against power to drive up the hill to come up with efficiency.<br />
<br />
The key here is to pick the right road. The hill should be steep enough to allow only regen using L mode to slow the car on the way down while keeping up with traffic, yet not too steep that brakes must be applied. Once the brakes are applied, some energy may (or may not) waste as heat, so the experiment becomes invalid. The best is to have the hill long enough so that cruise control takes care of the speed.<br />
<br />
Fortunately, I happen to drive on such road regularly: slope of about 8% and 4 miles long. Using cruise control at 50 MPH, I obtain the following.<br />
<br />
Flat road: 9 kW to 10 kW<br />
Up hill: 32 kW<br />
Down hill: -9 kW<br />
<br />
Power regenerated going down the hill is flat road power plus regen displayed, or 18 kW to 19 kW.<br />
<br />
Power used to go up the hill is total power minus power going on flat road, or 22 kW to 23 kW.<br />
<br />
Then the efficiencies are<br />
<br />
18 / 23 = 78% (worst case)<br />
19 / 22 = 86% (best case)<br />
<br />
<b>Power to the battery</b><br />
<br />
These are power shown at the display. But exactly where is that power applied/coming from? Is it at the motor? At the electronics between motor and battery? At the battery terminal? Obviously, it's not inside the battery. We have to make some guesses.<br />
<br />
When you step on the accelerator, displayed power goes beyond 100 kW, maybe even beyond 110 kW. Since the motor is rated for 104 kW, the power shown is not at the motor. It could be at the electronics or even the battery.<br />
<br />
When you use DCFC, power shown is sometimes 48 kW, which makes <a href="http://sparkev.blogspot.com/2015/12/sparkev-is-quickest-charging-ev-in-world.html">SparkEV the quickest charging EV in the world</a>. Given that the charger is capable of 50 kW, 48 kW would be 96%. It seems the power displayed is at the battery terminal.<br />
<br />
Then we can adjust by considering the battery efficiency. Let's assume 96% is the estimate of battery efficiency. The result we get is<br />
<br />
78% * 96% = 75% (worst case)<br />
<div>
86% * 96% = 82% (best case)</div>
<div>
<br /></div>
<b>Significant figures</b><br />
<br />
SparkEV only gives integer values for power. Indeed, this is why I picked some high power speed and hill to do the experiment to minimize the errors. If I had done this test in slight hill that resulted in only 1 kW difference, I may not even see the difference and large errors would result. For example, 1 kW shown might be 0.5 kW or 1.5 kW, resulting in 100% error! But for 10 kW (roughly), the errors are about 10%.<br />
<br />
However, it's not known how the rounding occurs. If 10 kW is shown, there are many possibilities. Some examples are 9.01 kW to 10.0kW, 9.5kW to 10.49 kW, 10.0 kW to 10.9 kW. Then which is it? Unfortunately, I don't dig that deep into this topic. I'll just assume 10% at nominal.<br />
<br />
Then the new estimates are<br />
<br />
75% * 90% = 68% (worst case)<br />
82% * 110% = 91% (best case)<br />
<br />
<b>If I had to choose...</b><br />
<br />
Well, there are lots of values, which one is correct? Probably none of them! We are trying to estimate the efficiency, not come up with absolutely correct value. My pick would be somewhere around 75%. Why? It's convenient to remember: 3/4 (three-fourth).<br />
<br />
<b>Ramifications</b><br />
<br />
If one drives up a hill, one has to drive down a hill eventually. For a gas car, all that energy to drive up a hill would be lost as heat when coming down. In effect, that's money floating away as brake dust and heat.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgQIoYZiK11AlQccyZEnbUT3lIjDihaKHGv0WSVKN9sfw-q3HLNYR93xT-BUcq9zr0Xj-04t2pgTIx-6UDO6CUsyDuszI_tHEK3KbrIErm-WFZiI_0MSQT3pXNjZnAx68shuLYmPulHC1iz/s1600/170410448.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgQIoYZiK11AlQccyZEnbUT3lIjDihaKHGv0WSVKN9sfw-q3HLNYR93xT-BUcq9zr0Xj-04t2pgTIx-6UDO6CUsyDuszI_tHEK3KbrIErm-WFZiI_0MSQT3pXNjZnAx68shuLYmPulHC1iz/s1600/170410448.jpg" /></a></div>
<br />
For SparkEV, 75% of that energy gets put back into the battery. That's money in the pocket (or battery). In addition, it saves wear and tear on the brakes. Indeed, this is why my brakes had cross-hatch pattern on the rotors as if they're new even after 7000 miles of driving. Also the lack of heat would result in much longer life for brake components and fluid, although Chevy still has brake fluid change interval at 30K miles.<br />
<br />
Combined, total monetary savings would be far more. Since gas car is 0%, it's meaningless to talk about percentage compared to those. But as energy cost savings and factoring in reduced brake wear, it could exceed 100% savings calculated as energy cost.<br />
<br />
<b>Alternative experiments</b><br />
<br />
Above experiment was just on a hill. One could also perform an experiment on typical driving scenarios. If the regen efficiency I found hold throughout the speed range, one could think of low speed traffic (slow and go) range to be about 75% of what's shown in <a href="http://sparkev.blogspot.com/2016/03/range-polynomial.html">range polynomial blog post</a> if one does not use the brake pedal to slow down. However, the efficiency may not hold at 75% throughout the speed range and regen power level. Also, one must apply the brakes to come to a stop or to stop rapidly. As such, 75% is meaningful only as one data point and nothing more. There should be more experiments to find out other values.<br />
<br />
One such experiment would be to capture the video of the display as one's driving. Integrating over time would give data even without driving on hills. I asked my dog to hold the camera, but the result was camera with bite marks, and no usable video. Maybe you'll have better luck.<br />
<br />
But even with video, one can only go so far. Display is still integer, and the update rate is about once a second and varying whereas hilly experiment was roughly constant power for many minutes. For slow acceleration and regen, this might be acceptable. But for high power regen (60 kW?) and acceleration (over 100 kW), there may not be enough to get much better data. As we all remember from second grade Simpson's rule, you need more boxes to get accurate result.<br />
<br />
<b>Beauty of SparkEV</b><br />
<br />
As mentioned before, this test is not possible with Prius, even if it had power display. One reason is that regen is so weak that hilly road test would not be possible without using friction brakes. I suspect this is true with all cars that have regen always tied to brake pedal.<br />
<br />
But there's another extreme. There are some cars that tout "one pedal driving" where releasing the accelerator pedal is used to bring the car to a stop. Since regen would get weaker at low speed, the car would expend energy from the battery to slow down. Some say BMW i3 and Tesla behave this way. In effect, this introduces the uncertainly similar to brake pedal induced braking (aka, blended brake); you wouldn't know if the car is using the power from the battery to slow down. That kind of car would be unsuited for this experiment.<br />
<br />
The beauty of SparkEV is that regen in L is strong enough, yet knowing that it is only used for regen if the brake pedal is not applied. Supposedly, the new Volt and Bolt have even more modes of regen, but there's nothing like simplicity of SparkEV. In fact, if L is not max regen already, GM should do an update so that L result in max regen without using the battery or the brakes. You really only need D (regen like gas car for old timers), and L (strongest regen using accelerator pedal for most efficiency).<br />
<br />sparkevhttp://www.blogger.com/profile/04362518920979349841noreply@blogger.com6tag:blogger.com,1999:blog-6875771813122616391.post-40400354423018906122016-05-03T20:01:00.000-07:002016-05-14T04:24:56.566-07:00Green car awardThere's a list by AAA for various cars for being "green". I think that list is flawed crock of sh*t, so I'll present a better list in this blog post.<br />
<br />
<a href="http://newsroom.aaa.com/2016/04/aaa-green-car-year-tesla-model-s-70d/">http://newsroom.aaa.com/2016/04/aaa-green-car-year-tesla-model-s-70d/</a> <br />
<br />
Tesla S70D takes the top spot despite the fact that it's one of the least efficient EV on the market. Reason given is that it's due to being luxury car and some other nebulous metric.<br />
<br />
Limited availability VW eGolf (83 miles range) takes third place, but it doesn't include other limited availability cars like Ford Focus Electric that's sometimes called poor man's Tesla for being "luxurious".<br />
<br />
Worse, far longer range Leaf with 107 miles range isn't even mentioned, despite the fact that it's sold far more widely. <br />
<br />
And most egregious, many gas cars are mentioned, but not SparkEV! Again, limited availability cars like SparkEV should be on the list since eGolf is. That is outrageous!<br />
<br />
You can make up anything you want when measured so subjectively. In other words, that list is crock of sh*t. In this blog post, I'll present a more objective list of "green" cars. For me, "green" is least use of energy, so it's pretty easy to quantify objectively.<br />
<br />
For EV, DCFC is a must. That's because DCFC allows one to drive far more than rated battery capacity in a day. For example, SparkEV is rated for 82 miles range, yet it's capable of driving 1000 miles in a day by using multiple DCFC sessions. That allows the car to be driven far more than non-DCFC cars, thus avoiding gas use.<br />
<br />
One might argue that Tesla S70D has far longer range, almost eliminating the need for gas car. While Tesla does get more range, one cannot always drive a sedan. Often, one would drive much larger van or SUV or even truck to haul stuff when gas car is needed.<br />
<br />
Also, BMW i3 gets about 25% better efficiency than S70D. To get equivalent energy use, Tesla driver would have to skip driving for a day every 5 days (drive 4 days, skip fifth day). Even against SparkEV would be skip driving 1 out of 6 days for Tesla S70D, still highly unlikely scenario.<br />
<br />
Rather than taking such scenarios into account, I simply list them in order of EPA's MPGe, a metric of efficiency. Then the list is completely objective without bias (sans DCFC). Approximate prices are after US tax credit plus nominal CA rebate, total of $10K off the MSRP.<br />
<br />
<table border="1">
<tbody>
<tr bgcolor="#AAAAAA"><td>Make/model</td><td>EPA MPGe</td><td>appx price USD</td></tr>
<tr><td>BMW i3</td><td>124</td><td>$35K</td></tr>
<tr><td>Chevy SparkEV</td><td>119</td><td>$16K</td></tr>
<tr><td>VW eGolf</td><td>116</td><td>$25K</td></tr>
<tr><td>Nissan Leaf (SV/SL)</td><td>114</td><td>$25K</td></tr>
<tr><td>Mitsubishi iMiev</td><td>112</td><td>$13K</td></tr>
<tr><td>Kia SoulEV</td><td>105</td><td>$25K</td></tr>
<tr><td>Tesla S70D</td><td>101</td><td>$65K</td></tr>
</tbody></table>
<br />sparkevhttp://www.blogger.com/profile/04362518920979349841noreply@blogger.com4tag:blogger.com,1999:blog-6875771813122616391.post-38345783568276142962016-03-24T16:14:00.000-07:002016-04-05T12:33:59.758-07:00Range polynomial climbing hillPreviously, I wrote about SparkEV range by finding a polynomial that fits observed power at various speeds. If you haven't, you should read that first as this post will expand on that idea to cover driving on hills.<br />
<br />
<a href="http://sparkev.blogspot.com/2016/03/range-polynomial.html">http://sparkev.blogspot.com/2016/03/range-polynomial.html</a><br />
<br />
Of course, that post was based on actual measurements and using parameters that mimic physical characteristics of the car, which was covered in an even earlier blog post.<br />
<br />
<a href="http://sparkev.blogspot.com/2016/01/sparkev-range.html">http://sparkev.blogspot.com/2016/01/sparkev-range.html</a><br />
<br />
In this post, we'll discuss what happens to power and range as the car is driven over various hills. Only uphill case will be discussed, because it's more important to know how far one can get up a hill. You can guesstimate that downhill will be 1/2 to 3/4 regeneration back into the battery. As such, starting with full battery charge on top of a hill is not a good idea. One would waste energy by using the friction brakes to slow down rather than getting "free" energy, which also wastes money by wearing out the brakes.<br />
<br />
<b>Caveat: these are made up numbers, and should not be trusted!</b> <br />
<br />
But remember, these are "made up" numbers, and plenty of seasoning should be used before digesting. See my methodology later in this post and make up your own mind as to the validity.<br />
<br />
While the simple case of power on flat road was probably closer to reality, additional power with hill climbing could be way off if the electrical efficiency does not stay constant. For smaller hills where the extra power is not all that much, it's probably accurate enough. But for very steep hills that require almost full power, they will be way off.<br />
<br />
How much off? Consider a hill so steep that the car cannot accelerate. Then full 100kW of power out of the battery would be used to maintain whatever speed it had when the hill was first encountered. If that speed was 1 MPH, then the range would be<br />
<br />
1 MPH * 18 kWh / 100 kW = 0.18 miles<br />
<br />
Worse, let's say the hill was so steep that the car started moving backwards even under full power out of the battery. Then the range would be negative! <br />
<br />
However, it's reasonable to assume things are not so bad when the power is much less than 100kW. You might think that efficiency change linearly with power, but that isn't the case. Efficiency explanation is too messy, involving back EMF and such, but you're welcome to research the topic.<br />
<br />
How much worse can it be? Without having motor efficiency figures and tables, it's impossible to know. I guesstimate up to about half of full power could be estimated as reasonably close to typical efficiency. So that's a spiciest seasoning: all these figures are probably good enough up to about half the full power. Where did half of full power being "good enough" come from? As I often tell you, <span style="font-size: large;"><b><br /></b></span><br />
<div style="text-align: center;">
<span style="font-size: large;"><b>I JUST MAKE STUFF UP!</b></span></div>
<br />
<b>Parameters</b><br />
<br />
First is to recognize what the hills are. Typically, hills are specified as percent grade: distance rise over distance run. One can look it up in Wikipedia and other sources to see what they mean.<br />
<br />
But what are the typical values? Infinite would be vertical, which is not possible while 100% would be 45 degrees. From google, we find "The National Road (built in 1806) had a maximum grade of 8.75%. Local roads are much higher (12% or 15% are sometimes allowed) Otter Tail MN County roads 6%, alleys 8% Driveways can be as much as 30% for a short distance."<br />
<br />
The dreaded "grapevine" (aka Tejon Pass) in CA is under 7% grade for about 12 miles.<br />
<br />
<a href="http://www.crashforensics.com/tejonpass.cfm">http://www.crashforensics.com/tejonpass.cfm</a><br />
<br />
There are steeper roads as well, as steep as 38%. But those roads are far shorter.<br />
<br />
<a href="http://www.foxnews.com/travel/2014/03/03/worlds-steepest-roads/">http://www.foxnews.com/travel/2014/03/03/worlds-steepest-roads/</a><br />
<br />
For those who are allergic to foxnews, huffpo shows similar.<br />
<br />
<a href="http://www.huffingtonpost.com/2014/02/28/steepest-streets-america_n_4871559.html">http://www.huffingtonpost.com/2014/02/28/steepest-streets-america_n_4871559.html</a><br />
<br />
There are also slight slopes in local freeways. I pick following grades and show the corresponding angles and additional force required from the motor.<br />
<center>
<table border="1">
<tbody>
<tr bgcolor="#C0C0C0">
<td bgcolor="#C0C0C0">grade%</td><td>0</td><td>1</td><td>2</td><td>3</td><td>5</td><td>8</td><td>13</td><td>21</td><td>34</td>
</tr>
<tr bgcolor="#C0C0C0">
<td bgcolor="#C0C0C0">degrees</td><td>0.0</td><td>0.6</td><td>1.1</td><td>1.7</td><td>2.9</td><td>4.6</td><td>7.4</td><td>11.9</td><td>18.8</td>
</tr>
<tr>
<td bgcolor="#C0C0C0">2014 (lb)</td><td>0</td><td>31</td><td>62</td><td>93</td><td>156</td><td>248</td><td>402</td><td>640</td><td>1003</td>
</tr>
<tr>
<td bgcolor="#C0C0C0">2015/16 (lb)</td><td>0</td><td>30</td><td>60</td><td>90</td><td>151</td><td>241</td><td>389</td><td>620</td><td>971</td>
</tr>
</tbody></table>
</center>
<br />
Keen observers will note that grade numbers are roughly Fibonacci numbers. Yeah, well, we're off by 1.<br />
<br />
Angles are simple arc tangent of grades. 2015 weighs 2866 lb and 2014 is heavier at 2967 lb. SparkEV cannot drive itself (yet), so I add 150 lb as driver weight and multiply by the sine of the angle for added force. See theory section below for math explanation.<br />
<br />
Something to note is that one could theoretically "push" SparkEV up Tejon pass at 8% grade if they can push 250 lb. I used to be able to do so, but not anymore. This is where having girlfriends with strong muscles could come in handy.<br />
<div>
<br /></div>
<b>Power</b><br />
<br />
Going up the hill requires extra power (duh!). How much extra depends on weight and speed. Weight is assumed to be empty car's weight + 150 lb (driver). We'll explore heavier case later in this post. Following are plots for additional power required at various speeds and grades.<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgbD-t8mjkPwc3MCgwcyjQRh_FfmIzfKEZzXCDhh7Q2qIYKvm62shlgvm2oTedInOPkYC_jKvgQlKzUL1cKT3UcJ1pI9hqG0MGHGBxcsf-RBc-7RdPJCUESo9C7JnduQIA2_A77Rfu8BPD7/s1600/2014_power_extra.gif"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgbD-t8mjkPwc3MCgwcyjQRh_FfmIzfKEZzXCDhh7Q2qIYKvm62shlgvm2oTedInOPkYC_jKvgQlKzUL1cKT3UcJ1pI9hqG0MGHGBxcsf-RBc-7RdPJCUESo9C7JnduQIA2_A77Rfu8BPD7/s1600/2014_power_extra.gif" /></a>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiYta6ZYsPeh4I3GHGbmpKPRElTCjUgSgdJ6Gf47Muqi6TO1zh50ARanLiAF8ve-GPCUKKwPokmvSRuEps3QLBc110kuRHPxQrmdRTnNnhtEadkbp0o_JgCu6ahvHNgu1j8glklak707WZR/s1600/2015_power_extra.gif"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiYta6ZYsPeh4I3GHGbmpKPRElTCjUgSgdJ6Gf47Muqi6TO1zh50ARanLiAF8ve-GPCUKKwPokmvSRuEps3QLBc110kuRHPxQrmdRTnNnhtEadkbp0o_JgCu6ahvHNgu1j8glklak707WZR/s1600/2015_power_extra.gif" /></a></div>
<br />
Note that additional power increase linearly with speed. But that doesn't mean going 0% grade will not use power. What's needed is the total power that includes driving at flat road found in previous blog post. Following plots show the total power.<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEitil5rRZRWM_AArdyg1HwhGzt5ZXpD5T0UXTiTMSNDJ4sLIu5VrBzjmG2ZP7VZrv0kVVuQO263UMhpG5MbWNhEpxk2M-jxMRpX8vUHP3ZpcRnRCC-GdeDDNfiK3vhMmVwIPgPxsG6MLMgT/s1600/2014_power_total.gif"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEitil5rRZRWM_AArdyg1HwhGzt5ZXpD5T0UXTiTMSNDJ4sLIu5VrBzjmG2ZP7VZrv0kVVuQO263UMhpG5MbWNhEpxk2M-jxMRpX8vUHP3ZpcRnRCC-GdeDDNfiK3vhMmVwIPgPxsG6MLMgT/s1600/2014_power_total.gif" /></a>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgv2PN_IXHJ6KWkYH7L5IHRPBawY4TO8CC6Myn82cuPznlXLf7Aa4PnvcsDNxRfZM7lgOwGqdatYHh0HQst7PZaszNvCydAaLmmv-1woosd1P9gkmUP8ZCYGDcmfzUGGn2_0Q2jY2QvWE_Q/s1600/2015_power_total.gif"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgv2PN_IXHJ6KWkYH7L5IHRPBawY4TO8CC6Myn82cuPznlXLf7Aa4PnvcsDNxRfZM7lgOwGqdatYHh0HQst7PZaszNvCydAaLmmv-1woosd1P9gkmUP8ZCYGDcmfzUGGn2_0Q2jY2QvWE_Q/s1600/2015_power_total.gif" /></a></div>
Something of interest would be to estimate the road grade based on car's power. For example, if the car shows power as 30 kW while traveling 45 MPH constant speed, the road has roughly 8% grade (tan color plot). Of course, this is with only the 150 lb driver and making sure there is no acceleration involved; cruise control is helpful. More cargo or twitch on the accelerator pedal will mean less grade, but it is useful as an estimate for maximum grade of the road.<br />
<br />
How well does grade estimation based on power work? For a particular stretch of road that I got 51.1 mi/kWh going down hill, the steep section is about 2.5 miles. From plugshare terrain view, topo map shows the elevation is from 800 ft to 1600 ft, or 800 / 5280 = 0.15 miles. Then the actual grade is <br />
<br />
0.15 / ((2.5^2-0.15^2)^0.5) * 100 = about 6%<br />
<br />
Driving through this area up hill, power shows between 28 kW to 33 kW at 55 MPH. From the graph, that occurs between 5% grade (magenta color plot) and 8% (tan color plot). That's pretty close, and I'm fairly confident that powers are pretty close to actual, especially at lower power levels under 50 kW. I had the dogs with me that added 125 lb extra. But I'll show later that the extra weight does not change this much at this grade.<br />
<br />
<b> </b><br />
<b>Range</b><br />
<br />
Now we can use total power to estimate the range at various speeds. Following plots show the range vs speeds. SparkEV is capable of 100 kW, but DCFC is only 50 kW, and even 90 MPH on flat road is less than 50 kW. It's not known what may happen when using power greater than 50 kW for extended periods of time, so the grade + speed that result in greater than 50 kW are shown as 0 miles range. One could go faster, but what I show is safest speed based on extended usage (ie, 20 minutes of DCFC).<br />
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<br />
Unlike the case of constant power use, such as using the heater / AC, that resulted in better range with slight speed increase, the shape of the range over speed for hilly road is the same as flat road case. Therefore, keep the speed low to maximize range, just like how one would drive on flat road for maximum range.<br />
<br />
Because the power needed to climb the hill can be substantial, it doesn't extend the range all that much with speed for steeper hills. For example, 8% grade (about that of maximum on Tejon pass) would result in roughly 30 miles range at 25 MPH vs 25 miles range at 65 MPH. As a percentage, it's large, but 5 miles make little difference. If the destination is at the top of a hill, speed is largely irrelevant at grades more than 5%.<br />
<br />
However, if one expects to drive beyond the hill top (going down or flat after climb), it may make sense to slow down a bit to save some energy.<br />
<br />
<b>Energy</b><br />
<br />
But range isn't as useful. We don't typically drive uphill for entire battery capacity. What we'd like to know is how much energy is used to drive certain number of miles uphill. This would require 3D plot. Simpler is to take some boundary conditions: 25 MPH, 45 MPH, 65 MPH.<br />
<br />
Following plots show the energy use over distance for various speeds. Since we're talking about shorter distances, we don't have to play safe with power, and we consider full power case. Power greater than 100kW are shown as full battery energy (not recommended / possible). But remember what I wrote in caveat above: they could be way off with higher power.<br />
<br />
25 MPH case<br />
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<br />
45 MPH case<br />
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<br />
65 MPH case<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpMlatdJjIDXzUfHBAk2qE95BnCr1zy5vhc2hrrUbar3qV59xRtKkUv2PpxYi9V9HeHjIY0VcF5UXQuprBc7oiDGKa9nW3zieoBevfVvaxhTta3AkheNpvUD9A_nS9YLnliBeE6ExOSnuC/s1600/2014_energy_65mph.gif"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpMlatdJjIDXzUfHBAk2qE95BnCr1zy5vhc2hrrUbar3qV59xRtKkUv2PpxYi9V9HeHjIY0VcF5UXQuprBc7oiDGKa9nW3zieoBevfVvaxhTta3AkheNpvUD9A_nS9YLnliBeE6ExOSnuC/s1600/2014_energy_65mph.gif" /></a>
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<br />
Note that SparkEV cannot drive 34% grade at more than 45 MPH. It's just as well; those roads are local, and one should not speed on them.<br />
<br />
<b>GVWR case</b><br />
<br />
All of the above are with 150 lb driver, probably the best case. With more passengers and cargo, weight will be more. The maximum weight is the gross vehicle weight rating. I can't seem to find this number through google, but I find it printed on the car's door as 3761 lb (3761-2866 = 895 lb of "cargo"). Only 2015 data is available.<br />
<br />
But there is a problem. With added weight, there will be more friction from rolling from the tires and wheel bearings. Since the range polynomial was derived using "light weight" as cargo, it could be very different with full GVWR. Unfortunately, we can't do much about that since we don't have the data; we can only assume things will be worse. Did I mention I make stuff up?<br />
<br />
Then we have the following. Remember, actual will be worse, though not quantified how much worse. And again, remember the caveat about higher power efficiency being much different than typical.<br />
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<br />
Something to note is that top speed at GVWR is only 40 MPH on 34% grade hills. It's just as well; on such steep hill, even 25 MPH might seem scary.<br />
<br />
Recall from total power discussion above that I drove 55 MPH through 6% grade and the power display showed between 28 kW and 33 kW with two dogs, about 125 lb extra. Even if I had almost 750 lb extra, the power would be only slightly more, maybe around 35 kW. Of course, this still neglects the rolling resistance effect, but it should be pretty close.<br />
<br />
<b>Can SparkEV climb Tejon Pass?</b><br />
<br />
In theory, SparkEV can easily climb over Tejon Pass. It's only 6% grade for about 12 miles.<br />
<br />
First, let's check the power. 8% grade at 65 MPH is about 50kW (half power) while 5% grade is much less. 6% grade at 65 MPH would probably (PROBABLY) have similar efficiency as typical, so we can use above plots.<br />
<br />
On the way down, it would recapture 50% to 75% of the energy via regenerative braking. But the problem is how much energy would it have when it gets to the bottom of the hill before the actual climb. If there's DCFC at the bottom of the hill, this is not a problem. Alas, that isn't the case.<br />
<br />
Going from South to North as of Mar. 2016, closest DCFC is at Castaic (1200 ft), some 36 miles away from Gorman peak at about 4200 ft, difference of 3000 ft (0.57 miles).<br />
<br />
23901 Creekside Rd, Santa Clarita, CA 91355<br />
<br />
That is average of 0.57 / 36 = 1.6% grade. Let's assume 2% (red color plot from 65 MPH energy graph) and things operate within the model parameters (efficiency stays at typical levels).<br />
<br />
2015 SparkEV would easily make it at 65 MPH for 35 miles of 2% grade with solo driver by using 70% to 80% of new battery capacity. Given that battery warranty kicks in at 65%, one could theoretically make it over the hill even with slightly worn battery. Remember, we need some margin, so we don't consider 100% case. Another interesting data is that average power required is roughly that of driving at 80 MPH on flat road.<br />
<br />
For GVWR case, it's unknown, because the range polynomial doesn't take added rolling resistance into account. But we can guesstimate by taking 3% grade case (about double actual grade, cyan color plot). That shows 65 MPH for 35 miles to use over 90% of new battery capacity. Unless one has a new battery and charged to 100%, SparkEV isn't likely to make it over the hill. It's also about average power at 90 MPH on flat road.<br />
<br />
But what if we go really slowly? It's too dangerous to drive at 25 MPH on freeway, so one should not do this. But as a thought experiment, is it possible? From 25 MPH graph, we see that 3% grade for 35 miles will need about 70% to 80% battery. So in theory, one can make it over the hill going really slowly. It's also about average power at 50 MPH on flat road, but going half the speed.<br />
<br />
Going up to the top of the hill is one thing, but getting to the charger on the other side is equally important. Next DCFC is located at Selma, CA, some 180 miles away from previous DCFC at Castaic.<br />
<br />
2950 Pea Soup Anderson Blvd, Selma, CA 93662<br />
<br />
This would make it impossible to use DCFC to travel over Tejon Pass. There really need to be DCFC at the bottom of the hill on both sides for this to work. For now, the only option for SparkEV is along 101 freeway to travel between SoCal and NoCal as in my fictional trans CA EV race blog post.<br />
<br />
<a href="http://sparkev.blogspot.com/2016/02/the-great-trans-california-ev-race.html">http://sparkev.blogspot.com/2016/02/the-great-trans-california-ev-race.html</a><br />
<b><br /></b>
<b>Theory</b><br />
<b><br /></b>
Theory on the basics of range polynomial was discussed in previous blog post, aptly named "range polynomial". Here, we add additional, which is basic Trigonometry and Physics.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEggBaxD2giu2UbdUwC-2EEQjn3or8obcMjYOHxB9_7WxnjcsTMP-Wt_W1pGN9tmVEVabeRUMz9gTd6-LxHq33_eFm11K7Uji9h0fggyop7G92QQNDt2bdx4OwAQDibjh4f5BoE1dDNHwxwx/s1600/06flR.gif" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEggBaxD2giu2UbdUwC-2EEQjn3or8obcMjYOHxB9_7WxnjcsTMP-Wt_W1pGN9tmVEVabeRUMz9gTd6-LxHq33_eFm11K7Uji9h0fggyop7G92QQNDt2bdx4OwAQDibjh4f5BoE1dDNHwxwx/s1600/06flR.gif" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">http://i.stack.imgur.com/06flR.gif</td></tr>
</tbody></table>
In the picture above, W is the weight of the car + cargo. Theta is the angle. But the angle is not given, only percent grade.<br />
<br />
Percent grade on a hill is rise over run. Then the angle is simply the arc tangent of percent (divided by 100). A quick review of Trigonometric magic word, so-caaaa-toe-ahhhh.<br />
<br />
SOH : <b>S</b>ine of an angle is <b>O</b>pposite side length divided by <b>H</b>ypotenuse length of a right triangle.<br />
CAH : <b>C</b>osine of an angle is <b>A</b>djacent side length divided by <b>H</b>ypotenuse length of a right triangle.<br />
TOA : <b>T</b>angent of an angle is <b>O</b>pposite side length divided by <b>A</b>djacent side length of a right triangle.<br />
<br />
Quick side note: sine in Spanish is "seno" which is also the body part. Math and anatomy, like peas in a pod!<br />
<br />
We invoke the TOA clause from above, and take inverse tangent (aka, arc tangent) to get the angle.<br />
<br />
Angle = arctan (grade_in_percent / 100)<br />
<br />
Once we have the angle, we can simply multiply the weight by the sine of the angle to find the additional force needed. Of course, we don't really need that at all; we can use Pythagorean theorem to bypass sine and tangent altogether, but that's left as exercise to your high school kids taking Trigonometry.<br />
<br />
Once the force is known, we need to find the power needed to overcome the added force as the car is traveling up. Obviously, faster speed, quicker one would acquire potential energy. It's simply force multiplied by speed.<br />
<br />
power_climbing = force * speed<br />
<br />
Because the power is specified as kiloWatts, conversions are needed. Doing bunch of hocus pocus conversions from magic miles and pound and slugs to MKS units, we arrive at power just for the climbing portion in kiloWatts.<br />
<br />
Because the operations are linear, power will simply add. You can prove it yourself or pay your kids to do it. We add flat road power from range polynomial to the additional power for climbing to get the total power for climbing at various speeds.<br />
<br />
power_total = power_flat_road + power_climbing<br />
<br />
Once we have the total power, we can multiply by time needed to travel some distance to find the required energy. Time, of course, is distance divided by speed. Once again, make sure the units are converted to MKS and arrive at the following.<br />
<br />
Energy = power_total * time = power_total * (distance / speed)<br />
<br />
After all this, we generate various plots of interest. Are they correct? It's homework!<br />
<br />
<b>Edit Apr. 5, 2016</b><br />
<br />
After some discussion on unrelated topic of SparkEV's fake noise maker (thanks for poking me, Norton), aka Pedestrian Friendly Alert Feature, PFAF (completely useless as my Prius is silent), I thought of a new way to estimate rolling resistance. It is roughly when low speed has about 1/2 of the range of flat road. From above, that occurs at about 2% grade (65 miles at 10 MPH). That shows the force to be about 60 lb.<br />
<br />
While air resistance may not be substantial at 10 MPH, static power of 1 kW could be taking significant portion. Plugging in the number to polynomial, 10 MPH result in 1.66kW, taking 60%. Then the rolling resistance force is 40% of 60 lb, or 24 lb.<br />
<br />
One can experiment this value on flat road. Using a bathroom scale pressed against the back of the bumper, push the car until it's moving at constant speed. I read about 35 lb when I do this, though it's changing much due to irregular pushing. I think that's close enough, so it's about 35/3100 = 1.13%<br />
<br />
Then the force calculation in appendix should change as follows. Since baseline includes the weight of the car and 150 lb driver, added force is only applicable to added weight minus the baseline.<br />
<br />
<span style="font-family: "courier new" , "courier" , monospace;"> if (year==2014) mass_baseline = (2967+150); end</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> if (year==2015) mass_baseline = (2866+150); end</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> force1 = ( mass_lb * sin(angle_radians) ...</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> + ( mass_lb - mass_baseline) * 0.0113 * cos(angle_radians) ...</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> ) / 2.2 * gravity; % Newtons</span><br />
<br />
Below are new graphs for GVWR case for 2015. Range penalty is about 5 miles for low slopes with GVWR.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEieutlYJRrEWZvTFEhLWARsrwUtYJ4MUov1LmJF9_9CRoeXZj-Ge_8Y9EtN99L6gY9n94bm-Y9tdN8Ks2X-1uZ8E28sFiFMYWc0iySkmn-HMuEu4jbWheYn-p94Jp_GxbO8Sls0sKAZ9W8d/s1600/2015gvwr1_power_extra.gif"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEieutlYJRrEWZvTFEhLWARsrwUtYJ4MUov1LmJF9_9CRoeXZj-Ge_8Y9EtN99L6gY9n94bm-Y9tdN8Ks2X-1uZ8E28sFiFMYWc0iySkmn-HMuEu4jbWheYn-p94Jp_GxbO8Sls0sKAZ9W8d/s1600/2015gvwr1_power_extra.gif" /></a>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgvEIwxivFf3w4-PG-6joDRvQq5vn_Xoc6aH6bSwH8iPe89w3Kp7KXXHQf3nJvIDcm5XJNgHGpaDkI1UXc-U23f4bh5KdVP83ug6AmH7M10yv9Q1ptzMVA3dNuss14Umb_Isw3x7-6Ktz_c/s1600/2015gvwr1_power_total.gif"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgvEIwxivFf3w4-PG-6joDRvQq5vn_Xoc6aH6bSwH8iPe89w3Kp7KXXHQf3nJvIDcm5XJNgHGpaDkI1UXc-U23f4bh5KdVP83ug6AmH7M10yv9Q1ptzMVA3dNuss14Umb_Isw3x7-6Ktz_c/s1600/2015gvwr1_power_total.gif" /></a></div>
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<br />
<b>Appendix</b><br />
<b><br /></b>
As before, Octave is used to analyze and generate the plots. New convention is adopted for this m-file: those ending with "1" are vectors (1D arrays) and "2" are matrices (2D arrays). For example, "force1" would indicate 1D array of force values.<br />
<br />
Copy-paste this into Octave to generate the plots or save to a file and play with it as you see fit. What grade would SparkEV fail to climb at any speed? What road would SparkEV fail to travel at specified speed limit due to steep grade?<br />
<br />
<span style="font-family: "courier new" , "courier" , monospace;">clear; close all;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">batt_2014 = 19;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">speed1_2014=[0 24 55 62];</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">power1_2014=[1 3.33 10.2 12.7];</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">batt_2015 = 18;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">speed1_2015=[0 30 55 60];</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">power1_2015=[1 3.9 10.6 12.73];</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">% power polynomial and max range</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">poly1_2014=polyfit(speed1_2014, power1_2014, 3)</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">poly1_2015=polyfit(speed1_2015, power1_2015, 3)</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">% range over slope</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">function added_power_vs_speed(year, mass_lb, poly1, batt)</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> speed1=0:5:90;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> grade1=[0 1 2 3 5 8 13 21 34]; %grade in percent</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> mph2kmps = 0.44704 / 1000;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> gravity = 9.8; %m/sec/sec</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> angle_radians=atan(grade1/100); %radians</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;"> % OLD! force1 = mass_lb / 2.2 * gravity * sin(angle_radians); % Newtons</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> if (year==2014) mass_baseline = (2967+150); end</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> if (year==2015) mass_baseline = (2866+150); end</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> force1 = ( mass_lb * sin(angle_radians) ...</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> + ( mass_lb - mass_baseline) * 0.0113 * cos(angle_radians) ...</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> ) / 2.2 * gravity; % Newtons</span><br />
<div>
<br /></div>
<span style="font-family: "courier new" , "courier" , monospace;"></span>
<span style="font-family: "courier new" , "courier" , monospace;"> % power only to overcome hill</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> force2 = repmat(force1, length(speed1), 1)';</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> speed2 = repmat(speed1, length(force1), 1);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> power_grade2 = force2 .* speed2 * mph2kmps; % kW extra for grades</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;"> figure; plot(speed1, power_grade2, 'o-'); grid on;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> axis([min(speed1) max(speed1) 0 100]);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> set(gca, 'xtick', speed1, 'ytick', 0:10:100);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> xlabel('speed (mph)'); ylabel('power (kw)');</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> legend(cellstr(num2str(grade1')), "location", "northwest");</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> title ([num2str(year) ' extra power vs speed various % grades']);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;"> % total power including extra power for grades</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> power1 = polyval(poly1, speed1);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> power2 = repmat(power1, length(force1), 1) + power_grade2;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;"> figure; plot(speed1, power2, 'o-'); grid on;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> axis([min(speed1) max(speed1) 0 100]);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> set(gca, 'xtick', speed1, 'ytick', 0:10:100);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> xlabel('speed (mph)'); ylabel('power (kw)');</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> legend(cellstr(num2str(grade1')), "location", "northwest");</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> title ([num2str(year) ' total power vs speed various % grades']);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;"> % ranges at slopes</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> range2 = speed2 * batt ./ power2;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> range2(power2>50) = 0;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> figure; plot(speed1, range2, 'o-'); grid on;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> axis([min(speed1) max(speed1) 0 100]);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> set(gca, 'xtick', speed1, 'ytick', 0:10:100);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> xlabel('speed (mph)'); ylabel('range (miles)');</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> legend(cellstr(num2str(grade1')), "location", "northwest");</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> title ([num2str(year) ' range vs speed various % grades']);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;"> %energy use over distance</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> miles2meters = 1/1609.344;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> hour2seconds = 3600;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> distance1 = 0:5:50;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> for speed_a1 = 25:20:65</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> force2 = repmat(force1, length(distance1), 1)';</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> power_grade2 = force2 * speed_a1 * mph2kmps; % kW extra for grades</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> power2 = polyval(poly1, speed_a1) + power_grade2;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;"> distance2 = repmat(distance1, length(force1), 1); %miles</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> time2 = distance2 ./ speed_a1; %hours</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> energy2 = power2 .* time2;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> energy2(power2 > 100)=batt;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;"> figure; plot(distance1, energy2, 'o-'); grid on;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> axis([min(distance1) max(distance1) 0 batt]);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> set(gca, 'xtick', distance1, 'ytick', round((0:(batt/10):batt)*10)/10);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> xlabel('distance (miles)'); ylabel('energy (kWh)');</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> legend(cellstr(num2str(grade1')), "location", "northwest");</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> title ([num2str(year) ' energy vs distance at ' ...</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> num2str(speed_a1) 'mph various % grades']);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> end</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">endfunction</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">added_power_vs_speed(2014, 2967+150, poly1_2014, batt_2014);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">added_power_vs_speed(2015, 2866+150, poly1_2015, batt_2015);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">added_power_vs_speed(2015, 3761, poly1_2015, batt_2015); %GVWR, 900 lb of cargo</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">%resize all plots for easy viewing</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">% for n=1:18; a=figure(n); set(a, 'Position',[200,100,440,300]); end</span><br />
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<br />sparkevhttp://www.blogger.com/profile/04362518920979349841noreply@blogger.com0tag:blogger.com,1999:blog-6875771813122616391.post-35764402099880998222016-03-03T16:52:00.000-08:002016-10-20T12:55:45.955-07:00Range polynomialPreviously, I wrote a blog post in trying to analyze SparkEV's range. It was done using known parameters of the car, such as weight, drag coefficient, and some guesses as to rolling resistance and efficiency. Basically, it was an attempt to model the car and estimate the range. If you haven't already, that blog post should be read first, because I discuss where the real world data comes from.<br />
<br />
<a href="http://sparkev.blogspot.com/2016/01/sparkev-range.html">http://sparkev.blogspot.com/2016/01/sparkev-range.html</a><br />
<br />
Since we're guessing some parameters, we can ignore the entire car, and only use observed range data to make some models. In this blog post, we'll do just that: model the power using polynomial, and derive the range and other interesting values using the polynomial. In short,<br />
<div style="text-align: center;">
<span style="font-size: x-large;"><b>WE'LL JUST MAKE STUFF UP!</b></span></div>
As such, one should read this blog post with plenty of seasoning (ie, should not trust any of it). I'll describe my methodology later in this post, so you can judge for yourself how accurate they might be.<br />
<br />
Below are plots of ranges as functions of speeds and various battery capacities.<br />
<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgr2hFN_6ndVcn4gcRPZF44LPBdWtWi0oKhI0gP0o86TrHva_yP9eTHi4BDYP9JV76Fz87JhN994mwernjuO3W5His6gDycVKEFzzunpACxhyphenhyphen6geI7Y4YjyWOkPDyfc4udrCVnIZYfXtb-O/s1600/2014_range_over_battery.gif"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgr2hFN_6ndVcn4gcRPZF44LPBdWtWi0oKhI0gP0o86TrHva_yP9eTHi4BDYP9JV76Fz87JhN994mwernjuO3W5His6gDycVKEFzzunpACxhyphenhyphen6geI7Y4YjyWOkPDyfc4udrCVnIZYfXtb-O/s1600/2014_range_over_battery.gif" /></a>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEijOMK6TqxbIVy2jU3rwoC0pj6qry8noEV7sAZhKvR85TDgsHL15M3TgyWP88pcUjVarrqGFi29kYa2Rpr2hu8MpUcWt2tSd4ULPorI4H_qysEmzuAxX3SEm8FLt3-UoJhTSXJI0jPE8bai/s1600/2015_range_over_battery.gif"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEijOMK6TqxbIVy2jU3rwoC0pj6qry8noEV7sAZhKvR85TDgsHL15M3TgyWP88pcUjVarrqGFi29kYa2Rpr2hu8MpUcWt2tSd4ULPorI4H_qysEmzuAxX3SEm8FLt3-UoJhTSXJI0jPE8bai/s1600/2015_range_over_battery.gif" /></a>
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Because the graphs show maximum ranges at various speeds and various battery capacities, one can estimate the range for partial battery. For example, if one charges 14 kWh using DCFC, and speed is about 45 MPH with little stopping, the maximum range for each DCFC session would be about 85 miles. If one charges 1.5 hours using 3.3kW L2AC (assume 80% efficient = 4kW) and drove at 45 MPH, maximum could be about 25 miles. As always, leave 10 miles as margin, so the actual could be 75 miles and 15 miles, respectively. Again, this is without running down the battery completely, but merely to get back to state of charge before the drive began.<br />
<br />
One can also guesstimate the battery capacity. For example, if one normally got 75 miles with 10 miles remaining driving 60 MPH with new battery that would be 18 kWh battery. Later, if he (or she; hi Lindsay!) is getting 60 miles with 10 miles remaining under same conditions (same road, driving habit, weather, etc), then the battery capacity would be about 15 kWh.<br />
<br />
<b>Range with extra power use</b><br />
<br />
Another interesting graph is to find what happens when extra power is used, such as with heater, AC, open windows with dogs sticking their heads out. The plots show ranges at speeds for various additional power use in kW. They are based on brand new battery, so old battery ranges would not apply. Still, one can get a "feel" for what extra power use would do to the range.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4HTjuxL0NdGHITaqZfhbb04YMoXqP4lN1RP0gNIdfABUNSYN09gRBbejZsZ79aYHvZCWoXkWkL5woid9kOKkf7KAIrtr4jIyp8OZIvnx2x3dZA0BfJwTFMv0VyvucysR4FwQVHNmQyeRy/s1600/2015_range_over_power.gif"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4HTjuxL0NdGHITaqZfhbb04YMoXqP4lN1RP0gNIdfABUNSYN09gRBbejZsZ79aYHvZCWoXkWkL5woid9kOKkf7KAIrtr4jIyp8OZIvnx2x3dZA0BfJwTFMv0VyvucysR4FwQVHNmQyeRy/s1600/2015_range_over_power.gif" /></a></div>
<br />
To read the graph, you have to convert the parameters to power in kW. For example, we can assume the heater takes 2kW on average, about two space heaters you might have in the bathroom, and windows up and driving at constant speed at 65 MPH. Then the maximum range would be bit under 70 miles with 2015 (red line). Leaving 10 miles as margin, usable range would be 60 miles.<br />
<br />
But if you decided to waste energy by rolling down the windows and blasting the heater, that could result in lot more power use. Let's guess 9 kW. Then the range at 65 MPH for 2015 would be bit under 50 miles (also red line), with 10 miles as margin would leave about 40 miles.<br />
<br />
We really should investigate lower battery capacity range with additional power use. I could do that and generate a 3 dimensional plot, but there'd be no way to effectively display it without using some active code such as Javascript. I hate active code in a web page; it's just inviting malware. Ah, the good old days of strict HTML when you never had to worry about malware, but I digress.<br />
<br />
What we can do is to find the worst case battery degradation, and use that as the basis for additional power drain. What is the worst case? SparkEV battery warranty is to about 65% capacity (35% below peak). According to MrDRMorgan of forum, this is found in warranty booklet page 14.<br />
<br />
<a href="http://www.mychevysparkev.com/forum/viewtopic.php?f=9&t=4457&start=28">http://www.mychevysparkev.com/forum/viewtopic.php?f=9&t=4457&start=28</a><br />
<br />
Then I guesstimate 60% capacity as maximum degradation, and plot the ranges with additional power drains.<br />
<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjfFa8NThopKEZG5nrcNWzb3hMrddqg2VmAJBllD72z-gEm4O3jEaFNXHYdp4JHttCOWMxUKv_v_a7-Kvi26J_iuxjRqLTe87iIYQK9lsbAcw6m7pMxV_RiDgFX3u0UW5P53gEX9R7P0APy/s1600/2014_range_over_power_worse.gif"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjfFa8NThopKEZG5nrcNWzb3hMrddqg2VmAJBllD72z-gEm4O3jEaFNXHYdp4JHttCOWMxUKv_v_a7-Kvi26J_iuxjRqLTe87iIYQK9lsbAcw6m7pMxV_RiDgFX3u0UW5P53gEX9R7P0APy/s1600/2014_range_over_power_worse.gif" /></a>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh1bDNW0GzyFU4RXwg5IwsOqYOgVeD77uivz8fhhCp70hknf_4BH-QHu5jrCkFc-WJ8WNurcYpc3YDuqB7Jv1vAWkfhzyFb5RPyFfidEFOEIx-VLaPnimRuaXqvoOSbpbBklwtYzRq-WZbz/s1600/2015_range_over_power_worse.gif"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh1bDNW0GzyFU4RXwg5IwsOqYOgVeD77uivz8fhhCp70hknf_4BH-QHu5jrCkFc-WJ8WNurcYpc3YDuqB7Jv1vAWkfhzyFb5RPyFfidEFOEIx-VLaPnimRuaXqvoOSbpbBklwtYzRq-WZbz/s1600/2015_range_over_power_worse.gif" /></a></div>
For 2015 with worst degraded battery driven at 65 MPH and 4 kW for heater use would result in about 35 miles range. With 10 miles of margin, usable would be 25 miles range. Of course, you can turn off the heater, radio, lights, and windows up in order to result in 45 miles (35 miles with margin). Yup, that's pretty bad, but it'd still be usable if one commutes only 40 miles a day (20 miles each way).<br />
<br />
If one can charge at work, even using the heater would be fine or 40 miles each way. And if the commute happen to be only on local road or in Los Angeles (entire city is one giant traffic mess), the range could still be be close to 80 miles (40 miles each way, or 80 miles one way with charging at work). But 80 miles in LA could take 4 hours; what, you get to work and clock out right away?<br />
<br />
<b>miles per kWh with extra power use</b><br />
<br />
Sometimes, forum discussion turns to miles per kWh battery used (hi Norton). We know someone did 7.2 mi/kWh for entire battery capacity using 2014 model (see previous blog post on range). But what would it be for various speeds and extra power use, such as heater? If one drives at local speeds (35 MPH), he'd get far higher mi/kWh than driven at freeway speeds (65 MPH). Below graphs show just that.<br />
<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiDpo-q7S2e1WG4Kyu3J-EDmFe_KomtbrJC7gLbCOeSHQZhrO40sE-LcW6uHD3-nun26C2nt8FCDdhUjEDEmIxm-xyfyFF7RGkXQv36Tn_oL_GFqH1vqCbjR5jOaPzamyBPDMEAEBv3yLAN/s1600/2014_mikwh_over_power.gif"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiDpo-q7S2e1WG4Kyu3J-EDmFe_KomtbrJC7gLbCOeSHQZhrO40sE-LcW6uHD3-nun26C2nt8FCDdhUjEDEmIxm-xyfyFF7RGkXQv36Tn_oL_GFqH1vqCbjR5jOaPzamyBPDMEAEBv3yLAN/s1600/2014_mikwh_over_power.gif" /></a>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgY5D8Dp6IfZtaFVcQ0U1gs0Rt2i7GX191zlShBizss_L6tEYNZTvpZXvkWzALDmmkBIusMDo3Q924-HD-lQlXzO4olCtLXSTFVCyFIELjtD5-YynE2IF1Zh6tluH4D-O92cVi9ynozKMUT/s1600/2015_mikwh_over_power.gif"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgY5D8Dp6IfZtaFVcQ0U1gs0Rt2i7GX191zlShBizss_L6tEYNZTvpZXvkWzALDmmkBIusMDo3Q924-HD-lQlXzO4olCtLXSTFVCyFIELjtD5-YynE2IF1Zh6tluH4D-O92cVi9ynozKMUT/s1600/2015_mikwh_over_power.gif" /></a></div>
<br />
Without any extra energy use (no heater, AC), one can expect pretty high mi/kWh at low speeds in local roads and traffic. Regenerative braking won't be 100% efficient, so it would take away from this with lots of braking. Still, careful driving could result in close to 8 mi/kWh (or 270 MPGe energy strictly from battery to wheels)<br />
<br />
Because these are only dependent on car's geometry, and not battery capacity, these numbers hold regardless of battery capacity. That assumes battery efficiency would not change as it degrades, which is not correct. Still, the battery should not be as big a factor compared to other parameters. Did I mention that I make stuff up?<br />
<br />
<b>How they're made</b><br />
<br />
There's a saying, if you want to eat sausage, don't find out how they're made. In this case, you probably want to find out how the plots are made. I mean, you drive a SparkEV, presumably because you did the research to find that it's the best car in the world, and not just as EV. Put it another way, you have to be smart and inquisitive to be a SparkEV driver. I think that's probably why Chevy has been limiting SparkEV sales: not enough smart people in the world. :-) (Unfortunately in my case, I happened on it by coincidence, not due to any smart research)<br />
<br />
Anyway, let's get to it. What we need is power at various speeds and battery capacity. Once they are known, we can find out everything else (range, mi/kWh, etc) without knowing anything about the car, or whether it's a car or a potato.<br />
<br />
Once we have the data, we can find a function that fits the data. As you might recall from basic Calculus, polynomials with enough order can fit just about everything. If there's infinite data, we can use infinite order polynomial series (prove it, Mr. Taylor!). Even without infinite data, we can use the polynomial to make up infinite data using the function to find data we don't actually have, and it should be pretty close to actual.<br />
<br />
<b>Polynomial theory</b><br />
<b><br /></b>
So the secret sauce is the combination of sparse, but enough data (not infinite) for power use over speed, and some polynomial function that fits the data. But there's a problem. We don't have a lot of data. As such, that will limit the polynomial order. But we also know that car's aerodynamic power is cube of speed. Then the minimum polynomial should be third power with some coefficients as follows.<br />
<br />
(coeff1 * speed^3) + (coeff2 * speed^2) + (coeff3 * speed) + coeff4 = power<br />
<br />
For third order polynomial, we need at least 4 data points of speed and corresponding power. Unfortunately, there aren't many. One is by bicycleguy at 0 MPH (1.25 kW). I have "rough" power at 30 MPH=3 to 4 kW and 60 MPH=12 to 13 kW. We have to extract power from other measurements. Following are available.<br />
<br />
2014 model = 140 miles at 24 MPH at 7.2 mi/kWh (digital trends)<br />
2014 model = 98 miles at 62 MPH at 5 mi/kWh (Tony Williams)<br />
2015 model = 93 miles at 55 MPH at 5.166 mi/kWh (me! 93/18kWh=5.166 mi/kWh)<br />
<br />
Converting to power is speed divided by mi/kWh. Then we have the following.<br />
<br />
2014: 0=1.25kW, 24=3.33kW, 62=12.4kW<br />
2015: 0=1.25kW, 30=3 to 4 kW, 55=10.6kW, 60=12 to 13kW<br />
<br />
Oops, 2014 is only 3 data while 2015 has range of power for speed at 30 MPH and 60 MPH. Due to lack of display resolution, 2015 power figure accuracy suffer far more. This is where hocus pocus make up stuff as you go along come into play. It's pure fantasy mixed in with some reality.<br />
<br />
We know that everything should result in higher power use. That means all the coefficients of the polynomial must be positive numbers. Yes, there could be some higher order effects (100th order?) that could cause our tiny 3rd order polynomial to exhibit weird behavior, but by and large, we can just guesstimate those effects to be small. Did I mention we make stuff up as we go along?<br />
<br />
<b>Making stuff up</b><br />
<br />
First, let's assume 1 kW at 0 MPH rather than 1.24 kW. It could be that bicycleguy had the lights on and his radio playing when he measured it. Besides, 1 is lot quicker to type than 1.24.<br />
<br />
2015 data is lot more tricky, because the display did not have enough resolution. In-between could be anything. Two data we have that are "pretty close" are 0 and 55 MPH. We can guesstimate 30 MPH as something like 3.5 kW and 60 MPH to be something like 12.5 kW to start.<br />
<br />
We plug in 2015 data to Octave (or Matlab) polynomial estimator, we get some values. Then some coefficients are negative! Especially troubling is the third order coefficient being negative. That means SparkEV would eventually generate power when going fast enough. There's no new Physics here, simple error in value. Then we play with the values (leaving 0 MPH at 1 kW) by tweaking small amounts until we have all positive coefficients.<br />
<br />
2015: 0=1kW, 30=3.9kW, 55=10.6kW, 60=12.73kW<br />
<br />
We have to come up with one additional data point for 2014 model. Given that 2014 is taller gear (motor spins lower RPM), we can guesstimate 55 MPH power could be slightly less than 2015. How much less? I don't know, let's just start with 10.5 kW. Then we do hocus pocus with the polynomial estimator and values until we get all positive coefficient. The result I like happens at the following.<br />
<br />
2014: 0=1kW, 24=3.33kW, 55=10.2kW, 62=12.7kW<br />
<br />
Something you should be aware is that the coefficients are extremely sensitive to data. If you'd like, you can do the sensitivity analysis, but since the data are "made up" anyway, analysis won't mean much. For now, we have all positive coefficients, making it consistent with the laws of Physics in our third order polynomial universe. Then the coefficients are as follows:<br />
<br />
2014: 2.1007e-005, 6.0466e-004, 7.0472e-002, 1<br />
2015: 3.5859e-005, 6.7172e-005, 6.2379e-002, 1<br />
<div>
<br />
What's interesting is that the linear term for 2015 is less than 2014. Since the linear term is related to weight, and 2015 weighs less than 2014, this is consistent with that. But then the gearing is different, too, so one could say that's also bogus rationale. The life of meta analysis is full of make beliefs.<br />
<br />
<b>Polynomial made up data</b><br />
<br /></div>
Using the polynomial, we can plot power and range over speeds. The equation for range is simply speed / power * battery where battery is 19 kWh for 2014 and 18 kWh for 2015.<br />
<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhWOccDlIdgMsmw42QIX16MetHFEgZmcefGz06kbR1_gOIMxkaxWUn60Sy___6j5C5I3tGGA6ANJHVmrLgtiDiB5XXDK1tn-_JtZqvCathPX_X5ZU7e5qCYmgVfD6qiq2i-Z5HEN69vf9As/s1600/polynomial_power.gif"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhWOccDlIdgMsmw42QIX16MetHFEgZmcefGz06kbR1_gOIMxkaxWUn60Sy___6j5C5I3tGGA6ANJHVmrLgtiDiB5XXDK1tn-_JtZqvCathPX_X5ZU7e5qCYmgVfD6qiq2i-Z5HEN69vf9As/s1600/polynomial_power.gif" /></a>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiFdwMZpwdyMz7hWedzarp9zHRSRXy9QHJXNQuocXDKgMl39KDET0-dUoNQ058AhgWtfj-r2tzOL0raFJwcIqs-rSQFg9txKSjQmlh8z7Z0k0D-XKrjwx2dhM7KjL-xgkCOWJp5QFQw435X/s1600/polynomial_power.gif"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiFdwMZpwdyMz7hWedzarp9zHRSRXy9QHJXNQuocXDKgMl39KDET0-dUoNQ058AhgWtfj-r2tzOL0raFJwcIqs-rSQFg9txKSjQmlh8z7Z0k0D-XKrjwx2dhM7KjL-xgkCOWJp5QFQw435X/s1600/polynomial_power.gif" /></a>
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Note that the ranges for 2014 at 24 MPH and 62 MPH are pretty close to the actual values found through experiment. For 2015, only range data I have is 55 MPH, which is also close to the actual; 62 MPH is also close to what was found by TonyWilliams. However, all of them are slightly lower than experimental data (ie, these are conservative values).<br />
<br />
<b>1000 miles a day revisited</b><br />
<br />
Now that we have more uniform data, we can revisit our 1000 miles a day test. The data may not be accurate, but they are at least uniform (accuracy? reality? they don't mean jack!) 1000 miles / 24 hours = 41.667 MPH. With 20 minutes of DCFC + 10 minutes to get on/off the freeway, we have to keep an average speed of 41.7 MPH to drive 1000 miles a day. Below is a plot of average speed over driving speed.<br />
<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhmFWzTNEpCTbGWEMozjsZ7TFk2Y5qiZEYYsa67-uE0tQiReH9ztq6ikqbwwaWPnCoKFr2avPcmGWoX4DXReRjHE-DUGXUr28scB-MAO8GFMEWqOTthnUMhaTziQFQuJonMKTPV-3O0H9Rn/s1600/1000_miles_a_day.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhmFWzTNEpCTbGWEMozjsZ7TFk2Y5qiZEYYsa67-uE0tQiReH9ztq6ikqbwwaWPnCoKFr2avPcmGWoX4DXReRjHE-DUGXUr28scB-MAO8GFMEWqOTthnUMhaTziQFQuJonMKTPV-3O0H9Rn/s1600/1000_miles_a_day.gif" /></a></div>
<br />
Note the red line for 41.7 MPH and another line for 20.8 MPH needed for 500 miles a day.2014 SparkEV with new battery could easily make 1000 miles a day, even when driven at 65 MPH. But with 2015 SparkEV, it could barely make it when driven at 70 MPH or 75 MPH (72.5 MPH?). So far, all the indications are that SparkEV should be able to drive 1000 miles in a day.<br />
<br />
You might poo-poo 1000 miles a day as something insignificant, but many cars without DCFC can't even drive 500 miles in a day.<br />
<br />
For example, Fiat 500e has 87 miles range, 24 kWh battery, 6.6 kW on-board charger. Let's assume 95 miles range at 65 MPH (1.46 hours) and 22 kWh (22 kWh / 6.6 kW / 85% efficiency = 3.92 hours). Then the average speed is only 95 / (1.46+3.92) = 17.6 MPH. That's not even enough to drive 500 miles in a day. 500e would need 112 miles range with 22 kWh to achieve 500 miles a day (5.1 mi/kWh). Given that 500e is less efficient than SparkEV, and SparkEV can barely reach 4.2 mi/kWh at 65 MPH (see plot way above), it's unlikely 500e could ever reach 500 miles a day.<br />
<br />
In another example, 24kWh Nissan Leaf DCFC is far slower than SparkEV. While it's not known how much slower over typical case for different cars and weather, we can guesstimate 20 minutes for 11 kWh (vs 20 min for 13.5 kWh for SparkEV). You can do the math, but that's not nearly enough to get 1000 miles a day; however, it would be enough to clear 500 miles a day. 30 kWh may be able to clear 1000 miles a day; that's left as exercise to Leaf owners who care to experiment.<br />
<br />
<b>Edit: 2016-10-20</b><br />
<br />
Someone drove over 1000 km in one day (16 hours) with SparkEV! That might be one day distance record for SparkEV. Below is the video.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<iframe width="320" height="266" class="YOUTUBE-iframe-video" data-thumbnail-src="https://i.ytimg.com/vi/-6Nn1o09OD4/0.jpg" src="https://www.youtube.com/embed/-6Nn1o09OD4?feature=player_embedded" frameborder="0" allowfullscreen></iframe></div>
<br />
<br />
Below is the discussion. It's in French since he's in Canada (yes, they sell SparkEV in Canada, Mexico, and Korea), but you can use google translate to view in any language.<br />
<br />
<a href="http://menu-principal-forums-aveq.1097349.n5.nabble.com/1000km-en-une-journee-td53319.html">http://menu-principal-forums-aveq.1097349.n5.nabble.com/1000km-en-une-journee-td53319.html</a><br />
<br />
It works out to 1050 km (650 miles) in 16 hours, which is 65.6 km/hr (40.6 MPH) on average. Had he driven 24 hours in same pattern, he would've driven 1575 km (975 miles). Such feat would not be possible with slower charging EV like Nissan Leaf (24 kWh version) or EV without DCFC like Fiat 500e.<br />
<br />
So for now, the real world range of SparkEV per day is 1050 km (650 miles) while leaving 8 hours for sleeping and extrapolated 1575 km (975 miles) in 24 hours without sleeping.<br />
<b><br /></b>
<b>Conclusion</b><br />
<br />
In this post, I tried to make up data that at least better fit known experimental values, and used lowest order polynomial to estimate various scenarios. Given enough time and money, one could obtain better data and better polynomial that would account for many other aspects of the car. But for now, this simple polynomial should be enough to get a rough idea of SparkEV performance over various battery capacities and energy use, and another hint to a possibility of 1000 miles a day.<br />
<br />
<b>Appendix</b><br />
<br />
All plots and analysis were generated using Octave (freeware Matlab clone), but Matlab should work as well. You can get Octave from<br />
<br />
<a href="https://www.gnu.org/software/octave/download.html">https://www.gnu.org/software/octave/download.html</a><br />
<br />
Below is my "m file". Copy-paste into Octave, or you can save it to a file and tweak as you see fit.<br />
<br />
<span style="font-family: "courier new" , "courier" , monospace;">clear; close all;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">speed=0:5:90;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">batt_2014 = 19;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">speed_2014=[0 24 55 62]; </span><br />
<span style="font-family: "courier new" , "courier" , monospace;">power_2014=[1 3.33 10.2 12.7]; </span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">batt_2015 = 18;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">speed_2015=[0 30 55 60];</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">power_2015=[1 3.9 10.6 12.73]; </span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">% power polynomial and max range</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">poly_2014=polyfit(speed_2014, power_2014, 3)</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">power_2014=polyval(poly_2014, speed); </span><br />
<span style="font-family: "courier new" , "courier" , monospace;">range_2014=speed./power_2014*batt_2014;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">poly_2015=polyfit(speed_2015, power_2015, 3)</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">power_2015=polyval(poly_2015, speed); </span><br />
<span style="font-family: "courier new" , "courier" , monospace;">range_2015=speed./power_2015*batt_2015;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">% plot power vs speed</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">figure;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">plot(speed, power_2014, 'o-', speed, power_2015, 'o-');</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">axis([0 90 0 40]); grid on;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">set(gca, 'xtick', speed, 'ytick', 0:5:40);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">title('SparkEV power'); xlabel('Speed (mph)'); ylabel('power (kW)');</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">legend('2014', '2015/16'); </span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">% plot range vs speed</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">figure;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">plot(speed, range_2014, 'o-', speed, range_2015, 'o-');</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">axis([0 90 40 150]); grid on; </span><br />
<span style="font-family: "courier new" , "courier" , monospace;">set(gca, 'xtick', speed, 'ytick', 40:10:150);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">title('SparkEV range'); xlabel('Speed (mph)'); ylabel('range (miles)');</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">legend('2014', '2015/16'); </span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">% function to have uniform range vs speed plot axis</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">function plot_speed_range(speed, ranges, legend_val)</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> plot(speed, ranges, 'o-'); </span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> axis([0 90 0 140]); grid on; </span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> set(gca, 'xtick', speed, 'ytick', 0:10:140);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> xlabel('Speed (mph)'); ylabel('range (miles)');</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> legend(cellstr(num2str(legend_val')));</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">endfunction</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">function plot_speed_mikwh(speed, mikwhs, legend_val)</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> plot(speed, mikwhs, 'o-'); </span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> axis([0 90 0 8]); grid on; </span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> set(gca, 'xtick', speed, 'ytick', 0:8);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> xlabel('Speed (mph)'); ylabel('miles/kwh');</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> legend(cellstr(num2str(legend_val')));</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">endfunction</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">% ranges for various battery capacity</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">function range_over_battery(batt, speed, power)</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> N=15;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> batt_var = 0:(N-1);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> batts_var = repmat(batt_var, length(power), 1)';</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> powers = repmat(power, N, 1);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> ranges = repmat(speed, N, 1) ./ powers .* (batt - batts_var); </span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> plot_speed_range(speed, ranges, batt-batt_var);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">endfunction</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">figure;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">range_over_battery(batt_2014, speed, power_2014);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">title('2014 SparkEV ranges for various battery kWh');</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">figure;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">range_over_battery(batt_2015, speed, power_2015);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">title('2015/2016 SparkEV ranges for various battery kWh');</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">% ranges for various power levels</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">function range_over_power(batt, speed, power)</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> N=10;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> power_var = 0:(N-1);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> powers_var = repmat(power_var, length(power),1)';</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> powers = repmat(power, N, 1) + powers_var;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> ranges = repmat(speed, N, 1) ./ powers * batt; </span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> plot_speed_range(speed, ranges, power_var); </span><br />
<span style="font-family: "courier new" , "courier" , monospace;">endfunction</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">figure;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">range_over_power(batt_2014, speed, power_2014);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">title('2014 SparkEV ranges for various power use');</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">figure;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">range_over_power(batt_2015, speed, power_2015);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">title('2015/2016 SparkEV ranges for various power use');</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">figure;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">range_over_power(batt_2014*.6, speed, power_2014);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">title('2014 SparkEV worst case ranges for various power use');</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">axis([0 90 0 90]); set(gca, 'ytick', 0:10:90);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">figure;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">range_over_power(batt_2015*.6, speed, power_2015);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">title('2015/2016 SparkEV worst case ranges for various power use');</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">axis([0 90 0 90]); set(gca, 'ytick', 0:10:90);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">% mi/kwh for various power levels</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">function mikwh_over_power(speed, power)</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> N=10;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> power_var = 0:(N-1);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> powers_var = repmat(power_var, length(power),1)';</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> powers = repmat(power, N, 1) + powers_var;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> speeds = repmat(speed, N, 1);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> mikwhs = speeds ./ powers;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> plot_speed_mikwh(speed, mikwhs, power_var);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">endfunction</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">figure;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">mikwh_over_power(speed, power_2014);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">title('2014 SparkEV mi/kWh for various power use');</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">figure;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">mikwh_over_power(speed, power_2015);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">title('2015/2016 SparkEV mi/kWh for various power use');</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">% Can you drive 1000 miles in a day using multiple DCFC?</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">batt1k_2014=13.25;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">range1k_2014=speed ./ power_2014 * batt1k_2014;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">time1k_2014=batt1k_2014 ./ power_2014; </span><br />
<span style="font-family: "courier new" , "courier" , monospace;">speed1k_2014=range1k_2014 ./ (time1k_2014+0.5);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">batt1k_2015=batt1k_2014;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">range1k_2015=speed ./ power_2015 * batt1k_2015;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">time1k_2015=batt1k_2015 ./ power_2015; </span><br />
<span style="font-family: "courier new" , "courier" , monospace;">speed1k_2015=range1k_2015 ./ (time1k_2015+0.5);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">figure;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">plot(speed, speed1k_2014, 'o-'</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> , speed, speed1k_2015, 'o-'</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> , speed, ones(length(speed), 1)*1000/24, 'r-'</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> , speed, ones(length(speed), 1)*500/24, 'm-');</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">axis([20 90 20 46]); grid on;</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">set(gca, 'xtick', speed); set(gca, 'ytick', 20:2:46);</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">title('SparkEV average speed (20 min for 13.25 kWh + 10 min to get off/on road)'); </span><br />
<span style="font-family: "courier new" , "courier" , monospace;">xlabel('Speed while running (mph)'); </span><br />
<span style="font-family: "courier new" , "courier" , monospace;">ylabel('Average speed including DCFC time (mph)');</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">legend(</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> '2014 average speed'</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> , '2015/2016 average speed'</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> , '41.7 mph needed for 1000 miles a day'</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> , '20.8 mph needed for 500 miles a day'</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"> , "location", "southeast");</span><br />
<br />
<span style="font-family: "courier new" , "courier" , monospace;">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span><br />
<span style="font-family: "courier new" , "courier" , monospace;">%resize all plots for easy viewing</span><br />
<span style="font-family: "courier new" , "courier" , monospace;"><br /></span>
<span style="font-family: "courier new" , "courier" , monospace;">% for n=1:11; a=figure(n); set(a, 'Position',[200,100,440,300]); end</span></div>
sparkevhttp://www.blogger.com/profile/04362518920979349841noreply@blogger.com3tag:blogger.com,1999:blog-6875771813122616391.post-76068076053177397452016-02-12T12:34:00.000-08:002016-02-12T12:43:20.389-08:00The great trans California EV raceThere are many videos of Tesla P90D doing drag race against much more expensive and/or powerful gas cars. While that's amusing, it's not something practical many would do. Far more interesting would be using EV to travel long distance using multiple DCFC. This hearkens back to the days of old when early gas cars were racing across long distances in their putt-putt cars. It would be fun and adventurous, and good PR for EV all at once, though I doubt regulators would ever approve of any kind of "race" today.<br />
<br />
In this post, I present a fictional idea for a race across California. Because I'm no community organizer, this is simply an interesting idea that's fun to think about. Imagine the early days of gas cars, instead they had today's EV. I can just picture silent movies with people charging using DCFC and sipping Starbucks coffee instead of carrying around gas cans if this actually happened 100 years ago.<br />
<br />
<b>The Race</b><br />
<br />
Below is a picture from plugshare.com of all DCFC locations from San Diego to Sacramento.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjjkWgj0x1t_jL3RulnlIR-EYttYXrHh8uTpxxB9h47nyO2Jshuk3Tjky3pAgGKpC8ab6Hr5TUX7HSL9vAj9lYz-L66FA3q14BORAspoFivLbVc7SzlH1Hw3t14nS6joYAzfPp3Nh774LO2/s1600/dcfc.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjjkWgj0x1t_jL3RulnlIR-EYttYXrHh8uTpxxB9h47nyO2Jshuk3Tjky3pAgGKpC8ab6Hr5TUX7HSL9vAj9lYz-L66FA3q14BORAspoFivLbVc7SzlH1Hw3t14nS6joYAzfPp3Nh774LO2/s1600/dcfc.jpg" /></a></div>
<br />
While it would be nice to get to the Oregon border, there aren't enough chargers for 80 miles range EV to quite make it that far. For CCS cars like SparkEV, the only route is the western one with single station at King City ($0.39/kWh!) between Monterey and Pismo beach. For Chademo cars like Leaf, only route is the eastern one along interstate 5 with big gap between Bakersfield and Visalia.<br />
<br />
Sticking to these charging points, it should be possible to make it from Mexican border in San Diego all the way to Sacramento, a distance of about 600 miles, ideally with 8 DCFC sessions. At average freeway speed of 65 MPH + 30 min for DCFC (43 MPH average), it should take 14 hours with 4 hours of breaks. Because of frequent breaks with EV (about every hour), driver is not likely to get fatigued. In fact, a short power nap while DCFC would be possible.<br />
<br />
In contrast, if gas cars need 30 min break (eat, pee, nap) after about 2 hours of driving, they would need 9.5 hours drive + 2 hours = 11.5 hours. If EV can charge 160 miles in 20 minutes + 10 minutes to get off/on freeway, they'd be pretty much the same convenience as gas cars.<br />
<br />
Because there is at least one "choke point" in the race, the charging plan would have to center around that. For CCS, that would be King City. Then two charging points around that at San Luis Obispo and Salinas will be needed. But outside of those three, the driver is free to choose charging spots. If the driver speeds too much, he'd lose range, and more charging sessions will be needed, resulting in lost time. If the driver is too slow, of course, he'd be slow. It will be a careful balance between speed and charging location selection.<br />
<br />
People in NoCal might want to visit SoCal (and vice versa), so the race could be both ways simultaneously. Their drive back home could be at their leisure, or they may decide to drive to origin of the race at leisure and scope out the charging spots before hand.<br />
<br />
<b>The Rules</b><br />
<br />
<b>First and foremost, this race is to strictly obey all laws.</b> How to enforce this isn't clear; one can use GPS and/or OBD plug to keep track of vehicle speed / location and disqualify for any infraction. But given that many (most?) cars on the highway exceed the speed limit, this might make it more hazardous than keeping up with the flow of traffic.<br />
<br />
One idea to prevent speeding might be to have gas motorcycle as "pace car" that precedes the leader by few car lengths (separate lane) and obeying traffic laws. All other cars would have to be slower than the gas motorcycle. Could this result in all EV having the same time? In CA, you get stuck in traffic, stuck in red light, stuck behind some dumb truck, select DCFC that happen to need waiting, any number of things could happen for different travel time.<br />
<br />
But even without that, this is where the EV shines. If one speeds much, he will get far less range, and lose time, or worse, get a ticket (automatic disqualification), or even worse get stranded before reaching the next charger (also disqualification). As such, speeding much more than traffic flow may be counterproductive. It will have to be a balance of low speed, yet not too low.<br />
<br />
Keeping up with this rule, any collision, regardless of fault or object (person, dog, car, UFO), is automatic disqualification. Basically, one has to drive carefully, or get disqualified. Yes, bad luck is a bitch, and could get you disqualified.<br />
<br />
<b>Second</b> rule would be that EV would have to be stock except wheels/tires (more eco the better!) and mod to add DCFC. As of now, only mod available is <a href="http://shop.quickchargepower.com/JdeMo-for-Rav4EV-JdeMORav4.htm">Jdemo for Rav4EV by quick charge power</a>. But they may have other mods soon, such as for Ford Focus Electric or even Fiat 500e. Absolutely not allowed is mod to increase battery capacity, like certain company is offering to add second battery, or completely different drive train.<br />
<br />
Mod to make the EV more aerodynamic may be allowed provided that such mod is available to other people (paid or free) as well and at least one other unrelated party has such mod. First rule would say any such mod would have to be legal, so being legal is absolutely required.<br />
<br />
<b>Third</b> and very obvious rule would be that it has to be driven only on electricity.<br />
<br />
<b>The Winner(s)</b><br />
<br />
Because the route taken must be different for different charging standard, this makes determining the winner tricky.<br />
<br />
One method could be to find the average speed over distance after at least one CCS and one Chademo car passed the finish line, and the winner is the one with highest average MPH.<br />
<br />
Another could be separate categories for CCS and Chademo (two winners) using above method.<br />
<br />
Another would be even more categories; due to different routes, winner of each category is based on average speed method described above.<br />
<br />
<ol>
<li>sub 70 miles range, such as iMiev</li>
<li>70-90 miles range, such as SparkEV, Leaf S, BMW i3, even Ford Focus Electric modified with Jdemo by quickchargepower.com</li>
<li>90 to 120 miles range, such as SoulEV, Leaf SV/SL, Rav4EV modified with Jdemo by quickchargepower.com</li>
<li>DCFC capable hybrids only running on EV, such as BMW i3Rex, Mitsubishi Outlander PHEV (someone could import it, who knows?). This might get tricky as to how to determine that no gas was used. Maybe some penalty could be assessed for gas use.</li>
</ol>
<br />
Or it could be many categories with each category having separate CCS/Chademo winners. This is probably the best, combining all three ideas above.<br />
<br />
In this day and age, this race can be on-going with the result posted on the internet. But there won't be any black and white newsreel coverage of the winner if not for an official sanctioned race day.<br />
<br />
<b>The Reward</b><br />
<br />
The winner will be proudly recognized as the first to win trans California EV race. Their faces will be featured in some silent film newsreel to be archived for later generations to admire and wonder at our primitive state of affairs in transportation. Their children will admire what kind of brave nut jobs their parents were to undertake such crazy adventure with the fear of getting stranded with so few DCFC chargers along the way, not to mention that they had to drive the car themselves and not sit behind self driving cars.<br />
<br />
Of course, that will be superseded by the next great race, "The great trans USA EV race", that to be superseded by "The great trans North America EV race" and so on and so forth. But there will be nothing like the first one with so many obstacles to overcome as "The great trans California EV race" as that will likely be the last interesting EV race where humans must be the driver.sparkevhttp://www.blogger.com/profile/04362518920979349841noreply@blogger.com0tag:blogger.com,1999:blog-6875771813122616391.post-57800040148604217972016-02-04T13:54:00.000-08:002016-05-24T17:03:19.162-07:00SparkEV pricing and depreciationThe impetus for my SparkEV adventure started with pricing. Basically, it was the lowest cost option, even cheaper than replacing the battery in old Prius. In my case, it was 0 down, $139/mo for 39 months. Including CA rebate of $2500, that works out to<br />
<br />
$139 * 39 - $2500 = $2921<br />
$2921 / 39 = $75/mo<br />
<br />
Include tax and license becomes bit more, but $75/mo is cheaper than most smartphone plans.<br />
<br />
<b>Lowest SparkEV "lease"</b><br />
<br />
But what is the lowest price lease deal? When I first got SparkEV, I thought I had pretty good deal. I mean, cheaper than most smartphone plans to lease quickest car under $20K and an EV at that made me feel pretty smug. Then I find out about even cheaper price starting Jan. 2016: FREE!<br />
<br />
<a href="https://www.waivecar.com/">https://www.waivecar.com/</a><br />
<br />
They give out 2 hours of free SparkEV "lease" (aka. rental). Given that SparkEV range is about 65 miles at 65 MPH, it's not likely to drive far. Still, it would be enough to go shopping for large items like 50 lb bags of dog food. In fact, one of the founders of the company was commenting that one of their first customers did exactly that. Gotta love a company that provides service for betterment of dogs and cats! See comments section in link below.<br />
<br />
<a href="http://www.greencarreports.com/news/1102044_ad-supported-car-sharing-gives-2-electric-car-hours-free-in-la">http://www.greencarreports.com/news/1102044_ad-supported-car-sharing-gives-2-electric-car-hours-free-in-la</a><br />
<br />
From cursory glance, it seems this idea could generate lots of profits. There are large pick up trucks used as rolling billboard that get 15 MPG or less in the city as well as having to do oil change, etc., and they would have to make profit to stay in business. Using SparkEV and not paying the drivers, instead collecting fee from them after first 2 hours seem to be a great idea to make lots of profit. I wish them the best of success. It's one of those, "now why didn't I think of that!"<br />
<br />
But this may cause potential "problem" for used SparkEV pricing. If waivecar does well, they may need more SparkEV than what comes from Chevy. They may turn to used market, or other car sharing companies may decide to use SparkEV, and may have to turn to used market. While this is just speculation, Chevy will probably discontinue SparkEV after Bolt comes out, which would make SparkEV more valuable even as spare parts car. Again, this is total speculation, but it doesn't look good to count on lower price for used SparkEV. Get'em while you can.<br />
<br />
<b>More lease deals</b><br />
<br />
Often, several media outlets showcase the low cost SparkEV lease. ev-vin has excellent blog that shows latest and greatest lease deals for various EV, SparkEV and more.<br />
<br />
<a href="http://ev-vin.blogspot.com/">http://ev-vin.blogspot.com/</a><br />
<br />
Some comments in November 2015 showed some people getting lease deals as low as $62/mo using calculations like I have above. Since then, factory lease deals seem to have disappeared, but SparkEV continues to be one of the lowest cost EV to lease. As of Jan 31, 2016, Fremont Chevy has $79/mo + $1895 down for 36 months<br />
<br />
($79 * 36 + $1895 - $2500) / 36 = $62/mo<br />
<br />
Add tax and it will be bit more. Still, $62/mo lease is pretty damn good for any car, not just EV.<br />
<br />
<b>Buy after lease</b><br />
<br />
Over the months, I've come to discover how great SparkEV really is. It's the best bang for the buck out there, including gas cars. I may decide to keep the car after lease expires by paying the residual, about $14K after 39 months. Given that new SparkEV MSRP is about $26K, $14K is almost half! Wow, that's a great deal! As with many things, not so fast.<br />
<br />
When the lease is first signed, the federal EV tax credit of $7500 is taken by the leasing company. In effect, they "bought" the car, and merely renting it to you. Their cost to buy would be $26K-$7.5K = $18.5K. Therefore, residual would represent $14K/18.5K (75%), or only 25% depreciation in 3.25 years. Considering that some cars lose half the value after driving out of dealer lots, 25% after over 3 years isn't bad at all. Or it's awful if you wanted to buy the car after lease expires.<br />
<br />
<b>Nissan Leaf depreciation</b><br />
<br />
There have been some popular media reports that EV (Nissan Leaf in particular) lose value quicker than any car. "Any car", as in not just EV but all cars. Insideevs.com had an article discussing the details of the depreciation.<br />
<br />
<a href="http://insideevs.com/2015-nissan-leaf-depreciates-car">http://insideevs.com/2015-nissan-leaf-depreciates-car</a><br />
<br />
They correctly point out that almost 50% depreciation in first year does not take into account the tax credit. In case of used car market, the depreciation should also consider state subsidy. That would make for $35K MSRP - $7.5K (fed) - $2.5K (CA) = $25K. 50% of $35K is $17.5K Actual depreciation for Leaf in first year would be 1-17.5/25 = 30%. While that's pretty large, it's nowhere near 50% that popular media make it out to be. In fact, it would be less depreciating than popular cars like Chevy Camaro (39%) and Kia Optima (35%).<br />
<br />
But is this real or just imagined? Is 2015 Nissan Leaf really only selling for $17.5K? Let's find out! Using cars.com as a search tool, we look for 2015 Nissan Leaf selling prices in SoCal area. The post subsidy price I use for new Leaf are $22K for S, $25K for SV, $27K for SL.<br />
<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi7bP0IREmesB_TQsJGhCuZszCuRL-ehMEuReyF9HwYrmKJpvwDc3YcgbkiiV4TU2EreAZpP50TFxK-zOxEEyBDhhmwn6oC9EMPV3-EXHWwbkirKeBofHAqrkMf9N5vor-NJkAH1Yyb8B9k/s1600/depreciate_Leaf_2015.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi7bP0IREmesB_TQsJGhCuZszCuRL-ehMEuReyF9HwYrmKJpvwDc3YcgbkiiV4TU2EreAZpP50TFxK-zOxEEyBDhhmwn6oC9EMPV3-EXHWwbkirKeBofHAqrkMf9N5vor-NJkAH1Yyb8B9k/s1600/depreciate_Leaf_2015.gif" /></a></div>
<br />
Unfortunately, there's not a whole lot, so the data is probably not very good. Still, one can pick up a used 2015 Leaf with less than 10,000 miles on it for about $17K. Depreciation in one year would be 1-$17K/$25K = 32%. But this includes Leaf S. While it's not known if they have Chademo option ($1200 option), we assume not. Then S depreciation would be 1-$17K/$22K=24%. We can estimate the first year depreciation as roughly 20% to 30%.<br />
<br />
Leaf also has 2014 and 2013 models. In case of 2014, there was only one: SL for $22K with 11K miles. That's 1-22K/25K=12% by selling for more than typical 2015 model. Since there's nothing special about 2014 model, we ignore this one.<br />
<br />
2013 is the year when Leaf switched to better battery (something about lizard) from pre 2012 model, and SV/SL has 6.6kW L2. There are lots of these for sale. So many, in fact, that I gave up after about 20 of them. Half of them are SV.<br />
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<div class="separator" style="clear: both; text-align: center;">
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgZA1pZGccbIobkFxaYSqWXVtCv2eZ_Rn6SpXPA800vt732r5dsCp9nF5hvdNPwhew84EwkcFS7KEWzWogYppIU39Kul6LcvZTGeAVfL19xUTY99jGvek9U9JBv0rr3SF-QR-HXKBzqnZ3c/s1600/depreciate_Leaf_2013.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgZA1pZGccbIobkFxaYSqWXVtCv2eZ_Rn6SpXPA800vt732r5dsCp9nF5hvdNPwhew84EwkcFS7KEWzWogYppIU39Kul6LcvZTGeAVfL19xUTY99jGvek9U9JBv0rr3SF-QR-HXKBzqnZ3c/s1600/depreciate_Leaf_2013.gif" /></a></div>
<br />
Depreciation is roughly 40% to 45%. While it's large, it's not so bad considering these cars have been driven for about 3 years.<br />
<br />
At 20,000 miles on average, that works out to 6666 miles per year, probably more since some cars could be less than 3 years. Wow, they are some low miles driven! SparkEV lease allows 10,000 miles per year, and these Leaf drivers would be only 67% of that. I guess Leaf drivers are home bodies that don't go to dog beach on regular basis.<br />
<br />
In terms of money, it's pretty awful. 2013 loses roughly $3500 per year, or $291/mo. I guess this is why Leaf lease used to be about $250 + some money down. To rub it in some more, SparkEV 3.25 year lease post subsidy is only $2921, $899/yr, $75/mo, or about 1/4 that of Leaf.<br />
<br />
It gets far worse. Since average miles driven is only 6666 miles per year, $3500/6666 miles = $0.53/mile! In contrast, SparkEV at same miles would be $899/6666 = $0.13/mile, 3.9 times cheaper. At 10,000 lease miles, it would be $899/10000=$0.09/mile, over 5 times cheaper than Leaf. Those are with my "ripped off" rate of $75/mo. Using recent lease deals of $62/mo, well, I don't even want to think about it!<br />
<br />
But in any case, Leaf loses about half the post subsidy price in 3 years.<br />
<br />
<b>SparkEV depreciation</b><br />
<br />
That's some scary thought if you're selling used SparkEV. While it's not the worst, losing 50% of post subsidy price (about $7500) after 3 years is pretty un-nerving. That means 2014 SparkEV would cost $7500 in 2017. If you're in the market to buy one, that will be great!<br />
<br />
Umm, yeah, not so fast. SparkEV ain't no Leaf! While Leaf is one of the slowest cars in 0-60 at 10 seconds at $25K, SparkEV at 7.2 seconds 0-60 is the quickest car at $16K, or even at $20K. SparkEV is also the quickest charging EV in the world, quicker than new Leaf with 110 miles range and BMW i3, sometimes even quicker than Tesla.<br />
<br />
<a href="http://sparkev.blogspot.com/2015/12/sparkev-is-quickest-charging-ev-in-world.html">http://sparkev.blogspot.com/2015/12/sparkev-is-quickest-charging-ev-in-world.html</a><br />
<br />
SparkEV is also the first EV from Chevy (aka, GM). You might claim EV1 was the first EV, but EV1 was never meant to be sold. If one goes by GM electric vehicle that's not sold to consumers, lunar rover from Apollo mission would be the first GM EV, or maybe there were EV prototypes before then. Obviously, we don't count those, so we shouldn't count EV1, either.<br />
<br />
<a href="https://en.wikipedia.org/wiki/Lunar_Roving_Vehicle">https://en.wikipedia.org/wiki/Lunar_Roving_Vehicle</a><br />
<br />
Then SparkEV is the first EV from GM. Yes, it's historic, and worthy of collector's value. This is especially so since Chevy will probably cancel SparkEV after Bolt comes out, limiting the number of SparkEV in existence. Then it's not clear how to price it. Is it priceless (free?) or billions of dollars? Well, it doesn't matter what our perception is. What mattes is how it's priced in used car market.<br />
<br />
Again going to cars.com, we get some prices for 2015 and 2014. We use $16K for new SparkEV price, $26K-$7.5K-$2.5K.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgvmhH5A3AuQig1VyDeKWdf6Z9ejUSwR32bJCYlZFSd4GMHchyU2zKODaJLtwNdwkchZ6OoQcMUp3hjNs29i88KXVG2Xz8-us7pNmK7s2PtEsnp83SN7lKSP1nbrt5VKYc98ZrJjTI3dSZX/s1600/depreciate_SparkEV.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgvmhH5A3AuQig1VyDeKWdf6Z9ejUSwR32bJCYlZFSd4GMHchyU2zKODaJLtwNdwkchZ6OoQcMUp3hjNs29i88KXVG2Xz8-us7pNmK7s2PtEsnp83SN7lKSP1nbrt5VKYc98ZrJjTI3dSZX/s1600/depreciate_SparkEV.gif" /></a></div>
<br />
Unfortunately, there are only 4 for sale. Why aren't people selling their old SparkEV? Must I ask? :-)<br />
<br />
With such small sample, it's hard to say if this is good or bad. There are six 2014/2015 Leaf for sale in used market while Leaf probably sold many times that of SparkEV in CA when new. Then it could be bad that there are 4 SparkEV vs 6 Leaf for sale. There shouldn't be any SparkEV for sale; are they nuts to try to get rid of such fantastic EV? ;-)<br />
<br />
Although the average is $16.5K, throwing out the max and min pricing, the average seem to be right around $15K with 10,000 miles. $16.5K would be more than new SparkEV price, and $15K would be depreciation of only 1-$15K/$16K = 6%. For worst case of $13,998 with 28,000 miles, it would be 12%. That isn't bad at all!<br />
<br />
More telling is the miles depreciation. 28,000 miles is about the number of miles for 3 year lease (10K miles per year). At lease end, it would be about $14K, pretty much what the residual would be. If one bought SparkEV instead of lease, it would lose about $2K in 3 years mileage, or $667/yr or $56/mo. With a year older car, it could be more loss in actual 3 years time, but probably not over $75/mo (or $62/mo). But remember, due to lack of samples, confidence is shaky.<br />
<br />
<b>Lowest SparkEV purchase pricing</b><br />
<br />
With the release of 2016 model year SparkEV at the tail end of Dec. 2015, there haven't been many lease deals. Factory lease expired a while ago, and there have been sporadic deals from ev-vin's web site. But what is the best price to buy it?<br />
<br />
Back in Apr. 2015 when I obtained SparkEV, Chevy had promo with $1000 rebate. So the total discount was $7.5K fed + $2.5K CA + $1K GM = $11K. In addition, Chevy was giving out $500 rebate to buy Bosche L2 EVSE for home charging at 240V. Total savings would be $11.5K, but SparkEV would've been $26500 at the dealer.<br />
<br />
From ev-vin's web site, I recently browsed over to Rydell Chevy in Northridge, CA. They show $1000 Chevy rebate plus another $1000 Rydell special for a total of $2000 savings. Then the price at dealer is shown as $24745. I checked the options, and it includes DCFC, a $750 option. If it didn't have DCFC, it would be $24K! WOW!<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhw_veAneQq5sYmAZSDzsL1oyeckKnaMX7hHjn0AfL9ZwWqIsO8wd1-sxfn84p_5oBsnmq9DVIlFEFu9RvW0l5C34ZgWBIpR1pIPK_tw8u9Swnjz7jbW7C-RL02IfUMr0sbYJNm_8F7Fkl0/s1600/Rydell_special.gif" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhw_veAneQq5sYmAZSDzsL1oyeckKnaMX7hHjn0AfL9ZwWqIsO8wd1-sxfn84p_5oBsnmq9DVIlFEFu9RvW0l5C34ZgWBIpR1pIPK_tw8u9Swnjz7jbW7C-RL02IfUMr0sbYJNm_8F7Fkl0/s1600/Rydell_special.gif" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small; text-align: start;"><a href="http://www.chevynorthridge.com/VehicleDetails/new-2016-Chevrolet-Spark_EV-Hatch_1LT_%28Automatic%29-Northridge-CA/2699286243">http://www.chevynorthridge.com/VehicleDetails/new-2016-Chevrolet-Spark_EV-Hatch_1LT_%28Automatic%29-Northridge-CA/2699286243</a></span></td></tr>
</tbody></table>
Well, "WOW" is only in CA. SparkEV is sold at $24K in Mexico, so the pricing is good for CA, but average for Mexico.<br />
<br />
<a href="http://www.chevrolet.com.mx/spark-ev-vehiculo-electrico.html">http://www.chevrolet.com.mx/spark-ev-vehiculo-electrico.html</a><br />
<br />
Still, applying $7.5K + $2.5K, it would be $14.5K for SparkEV 1LT. Considering SparkGas 1LT costs $15.1K, EV is cheaper than gas car!<br />
<br />
Now go and get'em; they only have few in stock, and who knows if Chevy will make any more.<br />
<br />
<b>Edit Feb. 12 2016</b><br />
<br />
It seems Chevy is finally selling SparkEV in Canada at retail level.<br />
<br />
<a href="http://www.gm.ca/gm/english/vehicles/chevrolet/spark-ev/overview">http://www.gm.ca/gm/english/vehicles/chevrolet/spark-ev/overview</a><br />
<br />
It's listed bit above $33K CAD, which is bit under $24K USD! On top of that, it shows DCFC comes as standard. That would put Canadian SparkEV $2750 cheaper than US models. What? Why is Chevy selling SparkEV for even cheaper in Canada than in CA where they get ZEV credit? If Canada isn't so far away, I could get into SparkEV import business.<br />
<br />
<b>Edit Feb. 21, 2016</b><br />
<br />
Is there a price war going on? Capitol Chevy of San Jose, CA shows 2LT price of $24,060. This includes DCFC option ($750), which would make base model to be $23,310.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhgCHM-8Whyphenhyphent_LTodnB_qCueorXTvYy-nSmCreXxycMF4Vtu_SxvWOSye_h5EXUXkvHrKilTxSn7RRmJjNUIsX5lVWZt8BUVjj2V7Q7xMnTikTczRoiVF1Qn16DFCSzZykuVchKZA3U-9yL/s1600/capitol_chevy_pricing.gif" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhgCHM-8Whyphenhyphent_LTodnB_qCueorXTvYy-nSmCreXxycMF4Vtu_SxvWOSye_h5EXUXkvHrKilTxSn7RRmJjNUIsX5lVWZt8BUVjj2V7Q7xMnTikTczRoiVF1Qn16DFCSzZykuVchKZA3U-9yL/s1600/capitol_chevy_pricing.gif" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><a href="http://www.capitolchevysj.com/new-inventory/index.htm?model=Spark+EV&&&&">http://www.capitolchevysj.com/new-inventory/index.htm?model=Spark+EV&&&&</a></td></tr>
</tbody></table>
Then after $7500 fed tax credit + $2500 CA rebate = $14,060 (or $13,310 if it didn't have DCFC)! Wow, that's approaching 3.25 year residual value for a BRAND NEW EV! How low can they go? This is getting very interesting.<br />
<br />
<b>Edit May 11, 2016</b><br />
<br />
Just when I thought things couldn't get any lower, it seems the price is even lower in Oregon and Maryland. Few weeks ago, I saw few for sale in Maryland for $17.9K. While that deal is gone, there are several in Oregon for $18.9K as seen in autotrader.com. This comes with DCFC, a $750 option!<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgtIziUYgTuOGz_2kytqyg9M7Tf2WrZwT7hzryyDfPHkY4aGXE1hjiRyoj3m4hBSB2SxUrqdOzgeKHnh-ymBRgEAYF-RAW176DhixQoqvr-dIDvIVrR5Yu9paMsVO8dQVKRQzk9PGaX4D47/s1600/chevy_of_bend.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgtIziUYgTuOGz_2kytqyg9M7Tf2WrZwT7hzryyDfPHkY4aGXE1hjiRyoj3m4hBSB2SxUrqdOzgeKHnh-ymBRgEAYF-RAW176DhixQoqvr-dIDvIVrR5Yu9paMsVO8dQVKRQzk9PGaX4D47/s1600/chevy_of_bend.jpg" /></a></div>
<br />
<br />
It's possible that these guys are sleazy, and reneg on the ad. But there are several dealers with sub-$20K pricing before subsidy, so the deal is probably real though with some caveats.<br />
<br />
Oregon doesn't offer state incentive, but they qualify for federal tax credit of $7.5K. Then the post subsidy price is only $11.4K! WOW!<br />
<br />
But wait, there's more! Because CA rebate is dependent on actually registering and using the car in CA, not where it's purchased, it could (COULD!) also qualify for $2.5K CA rebate (or $4K for low income). While it's not clear if OR deal requires residency or how to qualify for CA rebate for out of state purchase, it might (MIGHT!) be possible to get SparkEV for $8.9K.<br />
<br />
But for the low income who qualify for $4000 CA rebate and also has $7500 tax liability this year (ie, recently retired), that's only $7400! You can barely buy a decent used car for $7400. This is for a brand new car that seats 4 and powerful enough to go from 0 to 60 MPH in 7.2 seconds, quicker than 300ZX sports car from 1980's and smoother than a Rolls Royce.<br />
<br />
If anyone tells you that EV are slow and expensive and can't drive over 80 miles a day, just point them to SparkEV. It's cheaper than the cheapest new car, yet quicker than the sports cars of the past and smoother than the most expensive gas powered luxury car. It also has fast charger to allow many hundreds of miles of driving a day. Now THAT is how you debunk EV myth: SparkEV!<br />
<br />
<b>Edit May 24, 2016</b><br />
<br />
It seems there's some sort of price war going on between Nissan Leaf, VW eGolf, and SparkEV. Doing a quick search on auto trader on all electric cars, there are lots of Leaf S between $15.5K and $20K (84 miles range, some with fast charge), one Leaf SV for $19.9K (107 miles range, fast charge), several VW eGolf SE between $17.5K to $20K (83 miles range, no fast charge), and several SparkEV (82 miles range, fast charge) starting at $19K. It seems Leaf S has taken the lead on lowest purchase price EV, at least as advertised on autotrader.<br />
<br />
While Leaf and eGolf seats 5 vs SparkEV's 4, eGolf SE at such low price lacks fast charge, and not worth considering. Leaf's fast charge tapers off very rapidly relative to SparkEV. Both Leaf and eGolf are rated for 0-60 in about 10 seconds (30-60 in 7 seconds), far slower (boring!) than SparkEV's 7.2 seconds (30-60 in 4 seconds). If 5 seats are absolutely important above all else, Leaf SV at special sale might be best, followed by Leaf S with fast charge (DCFC). But if you can live with 4 seats, SparkEV still presents best bang for the buck for purchase.<br />
<br />
However, ev-vin's blog still shows SparkEV to be the lowest cost lease car, actually free under right circumstances. As such, SparkEV is the lowest cost car in the world even without considering superior performance.sparkevhttp://www.blogger.com/profile/04362518920979349841noreply@blogger.com4tag:blogger.com,1999:blog-6875771813122616391.post-20341818770854851632016-01-25T13:00:00.000-08:002016-10-20T12:54:06.273-07:00SparkEV rangeWhat is the driving range for SparkEV? Well duh, it's 82 miles. EPA tells us so. But is it really? When I was driving gas cars normally, I was almost always getting less MPG than EPA figures. When I "hyper miled", a term for driving technique for maximum fuel efficiency, I was getting far more than EPA figures. In this post, we'll explore some aspects of driving range and why they are not simple.<br />
<br />
<b>Maximum range</b><br />
<br />
A common question asked when people see me driving an EV is "what's the longest range you get?" The standard answer is 82 miles per EPA, but the true answer is more complicated. It is so very easy to hypermile with EV and get far more range, especially under favorable conditions. Below is a screen shot of a short drive under very favorable condition.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi5M84oW-sMFPBlqHiEW-HvoAT_2i40g9kcD9ED3kDgjXMmMTz2FNGyfxa5TBoW_f3ctkURPbO7MBxRTPJT6inBT3V9BJWSigJ8bWHRNHzh87qowrHaPjl1PrjX-4vcIwGz02BhPwywv5pD/s1600/51mi_per_kwh.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi5M84oW-sMFPBlqHiEW-HvoAT_2i40g9kcD9ED3kDgjXMmMTz2FNGyfxa5TBoW_f3ctkURPbO7MBxRTPJT6inBT3V9BJWSigJ8bWHRNHzh87qowrHaPjl1PrjX-4vcIwGz02BhPwywv5pD/s400/51mi_per_kwh.jpg" /></a></div>
<br />
Excuse the dusty image; dog hair and their dust are hard to keep off plastics. SparkEV has 19kWh battery of which some less is usable. Let's assume 90%, or 17kWh. Then the maximum range would be<br />
<br />
51.1 mi/kWh * 17 kWh = 869 miles<br />
51.1 mi/kWh * 33.7 kWh/gal = 1722 MPGe<br />
<br />
I probably could've done better if not for couple of stop lights. It shows that 82 miles EPA range depends on conditions with which the EV is driven. How did I achieve this phenomenal efficiency? It was mostly down hill, though I kept up with traffic.<br />
<br />
You might argue that same condition would result in infinite miles of range in gas cars due to downhill coasting, but that isn't the case. You still have to come to a stop, accelerate on green light, and keep up with traffic. Even if gas car coasts, they still have to apply the brakes eventually, giving up energy as heat while EV with regenerative braking would add energy into the battery upon braking. In fact, it would be possible for EV to have more energy at the end of "coasting" whereas gas car would always lose energy, even for tail light when the brakes are applied. While infinite miles on gas car is not possible, "greater than infinite" miles is possible with EV given enough long downhill.<br />
<br />
Therefore, maximum range on SparkEV is infinite miles!<br />
<br />
<b>No really, what is the </b><b>maximum </b><b>usable range per battery charge?</b><br />
<br />
Obviously, we can't always drive downhill. Then how far can SparkEV drive on a charge? Someone actually drove for entire battery charge at favorable driving condition (flat road, low speed), and achieved almost 140 miles!<br />
<br />
<a href="http://www.digitaltrends.com/cars/spark-ev-world-record/">http://www.digitaltrends.com/cars/spark-ev-world-record/</a><br />
<br />
So the practical upper limit on 2014 SparkEV is about 140 miles per charge. What the driver did was to drive at 24 MPH, lowest possible speed for cruise control, for about 6 hours. At low speed, EV does extremely well. Why not gas cars, too? We'll explore that later in this post.<br />
<br />
Something interesting from his experiment is the miles/kWh achieved: 7.3 mi/kWh. That translates to 246 MPGe. To drive 140 miles at 7.3 mi/kWh would need<br />
<br />
140 miles / 7.3 mi/kWh = 19.2 kWh (2014 SparkEV usable capacity)<br />
<br />
But he was driving 2014 SparkEV with bigger battery (21 kWh) than 2015 model. The total usable battery of 2014 SparkEV is 91.3% of full battery capacity of 21 kWh. If we assume the same percentage of battery capacity is used in 2015 SparkEV with 19 kWh battery, the usable battery capacity would be<br />
<br />
19 kWh * 91.3% = 17.4 kWh (2015 SparkEV usable capacity)<br />
<br />
The assumption I made above of 17kWh of usable battery capacity isn't far off.<br />
<br />
If we assume same power is needed to drive 24 MPH for 2015 model that has 17.4 kWh usable battery, the maximum range would be<br />
<br />
17.4 kWh * 7.3 mi/kWh = 127 miles<br />
<br />
But 2015 SparkEV is lighter by about 80 pounds as well as having lower gearing that's better for low speed (3.17 in 2014 vs 3.87 in 2015). While the usable battery capacity is just an estimate, it does give you an idea that the maximum driving range of SparkEV is around 130 miles when driven at 24 MPH, probably closer to 140 miles.<br />
<br />
<b>What range do you get for your driving?</b><br />
<br />
Above examples are under pretty optimistic scenarios. Typical driving would be far different. But what is typical? We can classify freeway and combined. Living in SoCal, it's hard to avoid the freeway and just drive local, so local only figure isn't available in my experiment.<br />
<br />
For freeway driving, I have 55 MPH figure from previous post: 84.7 miles driven with 9 miles remaining = 93.7 miles.<br />
<br />
<a href="http://sparkev.blogspot.com/2015/05/freeway-efficiency.html">http://sparkev.blogspot.com/2015/05/freeway-efficiency.html</a><br />
<br />
Strictly keeping at 55 MPH with windows closed and no AC/heat, one can expect bit over 90 miles range. Obviously, this is only possible in certain times, and not in summer heat or in rain (wipers, rain drop force, etc).<br />
<br />
At this point, let's check our results. Assuming 17 kWh usable battery capacity and 5 mi/kWh at 55 MPH, the maximum range would be<br />
<br />
5 mi/kWh * 17 kWh = 85 miles<br />
<br />
What!?!? How did 93.7 miles come about? Going the other way,<br />
<br />
93.7 miles / 5 mi/kWh = 18.74 kWh<br />
<br />
Hmmm. Something must be wrong. Indicated range is based on almost 100% of battery capacity? While it's possible, more likely is that I misread "short section of flat road" power reading; 10% off might be 10kW, and it could be possible that I was going slight uphill. In any case, 17 kWh usable battery capacity for 2015 model will be assumed based on experiment from 24 MPH for 2014 model with 21 kWh.<br />
<br />
Then what would be mi/kWh for driving 93.7 miles with 17 kWh?<br />
<br />
93.7 miles / 17 kWh = 5.5 mi/kWh<br />
<br />
Wow, that seems incredible. I think 17 kWh usable capacity makes more sense. Furiously waving my hands, let's just say that SparkEV range at 55 MPH is about 90 miles.<br />
<br />
<b>What range do you get for your combined driving?</b><br />
<b><br /></b>
More typical would be combined driving over long distance. I have kept my trip meter running since getting the car. The driving includes about a dozen 300 miles per day all-freeway trips using multiple DCFC as well as uphill, downhill, local, country road, city slicker havens, stuck in traffic. Below image shows the current mi/kWh. <br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjOVuEG1cBdC-AJ0RdJgNIy2dmem629GAvkx8OfMHnNAn-I3Az_BP6rkgMrtH6a9YN8Cf4w8bTT8UQd1RV65E2Vvqs3llALjzfPYftOIeC5HOmlYg_Naa0hUk2bvek7FuUnVEa9PVpcOknz/s1600/sparkev_mi_kwh.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjOVuEG1cBdC-AJ0RdJgNIy2dmem629GAvkx8OfMHnNAn-I3Az_BP6rkgMrtH6a9YN8Cf4w8bTT8UQd1RV65E2Vvqs3llALjzfPYftOIeC5HOmlYg_Naa0hUk2bvek7FuUnVEa9PVpcOknz/s1600/sparkev_mi_kwh.jpg" /></a></div>
<br />
<br />
At 5.1 mi/kWh, 17 kWh would result in<br />
<br />
5.1 mi/kWh * 17 kWh = 86.7 miles<br />
<br />
That's slightly better than EPA estimate of 82 miles. But if we assume almost 100% capacity is used as suggested by 55 MPH experiment,<br />
<br />
5.1 mi/kWh * 18.74 kWh = 95.6 miles<br />
<br />
That's when the battery is fairly new. What happens as the battery degrades? This is just a guessing game, but let's assume 20% degraded after 3 years, with average of 15% driven at degraded state. Because the battery capacity initially diminish as exponential decay, degradation would slow down as time goes on, which means one would spend longer time in more degraded state. But remember, this is just a guess as far as actual numbers are concerned.<br />
<br />
19kWh * 85% = 16.15 kWh<br />
5.1 mi/kWh * 16.15 kWh = 82.4 miles<br />
<br />
Well, well, what do you know? We're right at EPA estimated range when battery capacity degradation is taken into account. I don't know if this is what Chevy and EPA had in mind when they came up with the range estimate. It sure as heck doesn't make sense to use EPA MPGe figure to derive the range. Using 17kWh as usable battery capacity and 80% charger efficiency, it works out to<br />
<br />
119 MPGe / 33.7 kWh/gal * 17 kWh / 0.8 = 75 miles.<br />
<br />
Therefore, telling people that SparkEV typically gets 82 miles per charge is accurate, despite the EPA discrepancy.<br />
<br />
<b>Experimental range summary</b><br />
<br />
Range can be summarized as follows. All are with new battery with 2015 SparkEV and using actual experimental data.<br />
<ol>
<li>85 miles under typical conditions, summer and winter, and mostly with windows down (even in freeway) and dogs sticking their heads out.</li>
<li>90+ miles at 55 MPH windows up with slight elevation gain (about 500 ft).</li>
<li>130 miles at 24 MPH flat road without stopping.</li>
<li>869 miles in some long stretches of downhill, even with some traffic lights.</li>
<li>Greater than infinite miles (?) for very long downhill.</li>
</ol>
<b>Power vs speed: theory vs practice</b><br />
<br />
It's good to know the range based on actual driving, but it's not possible to experiment at different speeds. For example, we know the range would be less if driven at 90 MPH than at 55 MPH. But I don't have the luxury of long drives at 90 MPH on flat ground; there is vast government conspiracy to take away my driving license, even when I'm not exceeding the speed limit (I was nowhere near 186,000 miles per second!).<br />
<br />
I have to use short sections of flat road to test at lower speed. At 30 MPH, it was between 3kW and 4kW. At 55 MPH, it was almost solid 11kW. At 60 MPH, it was roughly 13kW to 14kW. Using these data points, we can construct a model for SparkEV power vs speed. Then we can figure out how much power is consumed at particular speed, and calculate the range as if it was driven at that speed.<br />
<br />
According to Physics, power required to overcome aerodynamic drag is proportional to cube of speed. Power required to drive at 60 MPH would be 8 times the power required to drive at 30 MPH (twice the speed, 2^3 = 8 times the power). But the data I collected show only 4 times the power at 60 MPH. Physics is wrong?<br />
<br />
Physics isn't wrong. We must also add other resistance. Tires are not friction-less, bearings, and all the moving parts contribute to some force resisting motion. As a simple model, force required to overcome "rolling resistance" is proportional to weight. Little detour in Physics lesson: That means the energy is also proportional to weight to drive the same distance (Work = Force * distance). Since the weight does not change, energy spent is constant at constant speed. But the rate of change of energy (power) is linearly related. Therefore, power needed to overcome this weight related friction is linearly increasing with speed.<br />
<br />
But wait, there's more! When the car is "on", it is using power, whether it's the day time running lights or the radio. This power is constant regardless of speed, unless you start to mess with AC/heat or blasting the radio.<br />
<br />
And then even more! At different power levels, current drawn would be different, but it would still go through same diameter wires. Higher current would increase electrical losses. This is not easy to quantify with the data we have. However, one can guesstimate this by looking at other electronics circuits. I use switching regulator as a model for this, which is about 90% efficient in operating range, much less in extreme low and high currents. This is also my motor efficiency (Engine efficiency).<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgTflWOarV5HZdHk9OIdqyJJFjw5YHQbPcWBVVB3aN3MELC8rw4PCv6JHvoXicUojSTev3ZWZKHMj4oTvFz9wQczbLzx-6eFiR-9nm2DSZH9ZuZzpmiL3gZFv3PGc1BC0y0fogS6WIAHBA9/s1600/TPS54040A_efficiency.gif" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="280" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgTflWOarV5HZdHk9OIdqyJJFjw5YHQbPcWBVVB3aN3MELC8rw4PCv6JHvoXicUojSTev3ZWZKHMj4oTvFz9wQczbLzx-6eFiR-9nm2DSZH9ZuZzpmiL3gZFv3PGc1BC0y0fogS6WIAHBA9/s320/TPS54040A_efficiency.gif" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">tps54040a (42V in switching regulator)</td></tr>
</tbody></table>
Now we can go and do bunch of calculations to figure out the relationship between power vs speed by combining the parameters, or we search the Internet to do that for us. If we plug in the right parameters, there are web sites that give us very nice summary of calculations. Here's an excellent web site that does exactly that. The link below has all the parameters to produce the data for SparkEV.<br />
<br />
<a href="http://ecomodder.com/forum/tool-aero-rolling-resistance.php?Weight=3000&WeightUnits=lbs&CRR=.01&Cd=.326&FrontalArea=27&FrontalAreaUnits=ft^2&FuelWh=33557&IceEfficiency=.9&DrivetrainEfficiency=.95&ParasiticOverhead=500&rho=1.225&FromToStep=5-200-5">http://ecomodder.com/forum/tool-aero-rolling-resistance.php?Weight=3000&WeightUnits=lbs&CRR=.01&Cd=.326&FrontalArea=27&FrontalAreaUnits=ft^2&FuelWh=33557&IceEfficiency=.9&DrivetrainEfficiency=.95&ParasiticOverhead=500&rho=1.225&FromToStep=5-200-5</a><br />
<div>
<br /></div>
Since not all values are available from the <sarcasm><i>extremely technically informative SparkEV user manual</i></sarcasm> following are some common values found on the Internet.<br />
<br />
Weight (lb): 3000 lb (google)<br />
<br />
Coeff. of rolling resistance (Crr): 0.01 (<a href="https://en.wikipedia.org/wiki/Rolling_resistance">https://en.wikipedia.org/wiki/Rolling_resistance</a>, tire on asphalt)<br />
<br />
Drag coefficient: 0.326 (<a href="http://media.gm.com/media/us/en/chevrolet/vehicles/spark-ev/2014.html">http://media.gm.com/media/us/en/chevrolet/vehicles/spark-ev/2014.html</a>)<br />
<br />
Frontal area (sq ft): 8.8 / 0.326 = 27 sq ft (<a href="http://www.mychevysparkev.com/forum/viewtopic.php?f=6&t=4003&start=10">http://www.mychevysparkev.com/forum/viewtopic.php?f=6&t=4003&start=10</a> gives drag area, divide by drag coefficient gives frontal area.)<br />
<br />
Fuel energy density (Wh/gal): 33557 (summer blend drop down option)<br />
<br />
Engine efficiency: 0.9 (guess based on switching regulator)<br />
<br />
Drive train efficiency: 0.95 (guess; default value)<br />
<br />
Parasitic overhead: 500 (lights are about 250 Watts, double it as guess)<br />
<br />
Air density: 1.225 (default value)<br />
<br />
Then it spits out a nice table. I reproduce just from 0-90 MPH, maximum speed of SparkEV and few more. I added the last column which shows the range assuming 17kWh battery capacity.<br />
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgUP5Ez5uAoY7e5RG9ETYpfDHmJWFY4o7MGEAnINuOWl520l9VjJ_6p-Yh9G2SdxWWp74emqKDKRbMnVGwkiZGdjLnq-4_FUs-YMV3X4OUrXxfHHwH5LyG3BTAv335z9ivL1HQmUKQ8ALiU/s1600/calculated_typical.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgUP5Ez5uAoY7e5RG9ETYpfDHmJWFY4o7MGEAnINuOWl520l9VjJ_6p-Yh9G2SdxWWp74emqKDKRbMnVGwkiZGdjLnq-4_FUs-YMV3X4OUrXxfHHwH5LyG3BTAv335z9ivL1HQmUKQ8ALiU/s1600/calculated_typical.gif" /></a></div>
<br />
<br />
Yellow highlights the key data to be discussed. Green cells are actual experiment data that match the calculations. As you can see, 30 MPH is between 3kW and 4kW, 55 MPH is bit above 11kW, 60 MPH is between 13kW and 14kW, close to what was observed. This tells me the parameters found are pretty close to actual values.<br />
<br />
<b>Range data analysis</b><br />
<br />
Again, let's assume the battery capacity of 17 kWh. Something to keep in mind is that these are just estimates. For example, the motor may not hold 90% efficiency throughout the speed range. Still, it gives some indication of what SparkEV ranges could be.<br />
<br />
At 25 MPH (2.7 kW), it would be good for 6.3 hours of driving, which would be 25*6.3 = 158 miles range. In the experiment above, the driver only reached about 140 miles. Was he overweight? Did he make some stops? Did he slow down? More likely, the parameters I use are not exactly what he had. His experiment was with 2014 model which was about 80lb heavier as well as larger battery than 2015 model. To achieve close to 140 miles, one would have to drive between 30 MPH and 40 MPH. Still, that's close enough for this exercise.<br />
<br />
We can evaluate EPA figures as well. EPA range is 82 miles. From the table, that range is achieved when driven at constant 55 MPH. Unfortunately, this includes all driving conditions, not just the highway. Then we turn our attention to EPA's MPGe which separates city and highway.<br />
<br />
EPA rates SparkEV as 119 overall (between 60 MPH and 65 MPH from table), 128 city, and 109 highway. While city figure is complicated due to multiple stops one has to consider, the highway figure is presumably based on much simpler driving dynamics. From the table, we can see that 109 MPG is reached at speed bit above 65 MPH. I suspect it was closer to 65 MPH with the heavier 2014 model of SparkEV. Also of significance at 65 MPH is the range of about 65 miles. Considering one doesn't drive to empty battery, actual range would be less, maybe 55 to 60 miles.<br />
<br />
An interesting aside is the theoretical maximum speed of SparkEV. While SparkEV is electronically limited to 90 MPH (and saving me from getting my license taken away... again!), ecomodder web site shows all the way to 200 MPH. SparkEV is capable of 100kW, and the speed at which 100kW is needed is over 125 MPH. Without electronic limit, that's the absolute maximum speed. At that speed, the range would be only 22.3 miles. Taking some margins into account, usable range would be 12 to 17 miles.<br />
<br />
But SparkEV may not sustain 100kW for very long. The longest known sustained battery use is 48 kW at DCFC. 51 kW is used at 100 MPH, 45 kW at 95 MPH. Well, 95 MPH close enough to 90 MPH with some margin, and that's probably why SparkEV is electronically limited to 90 MPH. At 90 MPH, range would be only 40 miles. Taking some margins into account, usable range would be 30 to 35 miles.<br />
<br />
In summary, the maximum range for SparkEV on flat road is between 40 miles (90 MPH) and 150 miles (25 MPH, lowest speed limit in most of US). Note that all of these values are with windows closed, no heat / AC, just simple driving at constant speed on flat road. Range will be less for any additional drain on the battery, such as two 150lb dogs sticking their heads out the window. In addition, maximum range should be de-rated to take into account some margin; 10 miles is a reasonable number. Then the usable range is between 30 miles (90 MPH) to 140 miles (25 MPH).<br />
<br />
Screw it. It's all just too messy. Just say it's 82 miles.<br />
<br />
<b>Is 1000 miles per day using DCFC possible?</b><br />
<br />
Previously, I wrote a blog post that 1000 miles per day using DCFC is possible.<br />
<br />
<a href="http://sparkev.blogspot.com/2015/05/dcfc-quick-charge-and-driving-from-la.html">http://sparkev.blogspot.com/2015/05/dcfc-quick-charge-and-driving-from-la.html</a><br />
<br />
But is it really? Now that we have better range estimates, we can do some checks to debunk (or validate) the assertions. I'm using 17 kWh as maximum battery capacity. 80% of that is 13.6 kWh. Knowing at 12% to 89% took 13 kWh in 20 minutes, 13.6 kWh in 20 minutes starting at lower state of charge may be possible. Adding 5 minutes to get off the freeway and and another 5 minutes to get back on, total time for DCFC is 30 minutes.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgzAttTK3SQcYFVGLAVzzmVjRYLuJTUMDhriDGsx486jH1JIU-O-dwOX1eQAF6MuGrJie2zyb61oG1AnW_AvJW-RudADcCPQ9UETupjzcQENImDW1pJAPn6tzM84eKbwgCvHt5IV_iRT2nc/s1600/89%2525_sparkev.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgzAttTK3SQcYFVGLAVzzmVjRYLuJTUMDhriDGsx486jH1JIU-O-dwOX1eQAF6MuGrJie2zyb61oG1AnW_AvJW-RudADcCPQ9UETupjzcQENImDW1pJAPn6tzM84eKbwgCvHt5IV_iRT2nc/s1600/89%2525_sparkev.jpg" /></a></div>
<br />
Driving at 65 MPH, the range is 66 miles. 80% of that is 53 miles. Time to drive is 0.82 hours (53/65). Adding 0.5 hours for DCFC equals 1.32 hours. 53 miles / 1.32 hours = 40 MPH average. 24 hours of this would be 964 miles. It's close, but not quite 1000 miles in a day.<br />
<br />
Doing the same with 55 MPH (83.3 miles range, 80%=67 miles, 1.2 hours drive + 0.5 DCFC = 1.7 hours, 39 MPH average), result is 934 miles, less than 65 MPH case.<br />
<br />
Doing the same with 70 MPH (59.4 miles range, 80%=47.5 miles, 0.63 hours drive + 0.5 DCFC = 1.13 hours, 42 MPH average), result is 1006 miles. So it is theoretically possible to drive over 1000 miles in a day at 70 MPH using 21 (24/1.13) DCFC sessions. I'm not crazy enough to try this, but I'm sure there are loons out there.<br />
<br />
<b>Edit: 2016-10-20</b><br />
<br />
Someone drove over 1000 km in one day (16 hours) with SparkEV! That might be one day distance record for SparkEV. Below is the video.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<iframe width="320" height="266" class="YOUTUBE-iframe-video" data-thumbnail-src="https://i.ytimg.com/vi/-6Nn1o09OD4/0.jpg" src="https://www.youtube.com/embed/-6Nn1o09OD4?feature=player_embedded" frameborder="0" allowfullscreen></iframe></div>
<br />
<br />
Below is the discussion. It's in French since he's in Canada (yes, they sell SparkEV in Canada, Mexico, and Korea), but you can use google translate to view in any language.<br />
<br />
<a href="http://menu-principal-forums-aveq.1097349.n5.nabble.com/1000km-en-une-journee-td53319.html">http://menu-principal-forums-aveq.1097349.n5.nabble.com/1000km-en-une-journee-td53319.html</a><br />
<br />
It works out to 1050 km (650 miles) in 16 hours, which is 65.6 km/hr (40.6 MPH) on average. Had he driven 24 hours in same pattern, he would've driven 1575 km (975 miles). Such feat would not be possible with slower charging EV like Nissan Leaf (24 kWh version) or EV without DCFC like Fiat 500e.<br />
<br />
So for now, the real world range of SparkEV per day is 1050 km (650 miles) while leaving 8 hours for sleeping and extrapolated 1575 km (975 miles) in 24 hours without sleeping.<br />
<br />
<b>SparkEV theoretical worst case</b><br />
<b><br /></b>Above analysis is a typical case using values that match the experimental data. Now let's explore the worst case. I don't mean turn up the heater and open the windows. I mean things like changing the tire to less efficient model or the motor/battery has worse efficiency due to age.<br />
<br />
Worst case rolling resistance for tire on asphalt from Wikipedia is 0.15, probably when using super wide tires. Who knows? Someone may want to install Corvette rims and tires on SparkEV. Some people are insane as Tesla appropriately name their driving mode.<br />
<br />
We guessed engine efficiency to be 90% (bit less than DCFC), but it could be less especially with aging battery and not-as-well lubricated motor and gears. Using 80% as engine efficiency, the same as L1 charging efficiency, we get the following.<br />
<br />
<a href="http://ecomodder.com/forum/tool-aero-rolling-resistance.php?Weight=3000&WeightUnits=lbs&CRR=.015&Cd=.326&FrontalArea=27&FrontalAreaUnits=ft^2&FuelWh=33557&IceEfficiency=.8&DrivetrainEfficiency=.95&ParasiticOverhead=500&rho=1.225&FromToStep=5-200-5">http://ecomodder.com/forum/tool-aero-rolling-resistance.php?Weight=3000&WeightUnits=lbs&CRR=.015&Cd=.326&FrontalArea=27&FrontalAreaUnits=ft^2&FuelWh=33557&IceEfficiency=.8&DrivetrainEfficiency=.95&ParasiticOverhead=500&rho=1.225&FromToStep=5-200-5</a><br />
<br />
<span style="font-family: "times new roman";">To save you the trouble, below is the screen shot of the table for worst case.</span><br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgAdwBPDC_IxUsew5rTX6EZ7kKI8mApjsZwRD-i1mYh8ZEil4hcd-XgwOb5lgN8KfHzIKIDQVHfWj2WrkhRyO1KAcoTyuHH65f60JgF7u-gRrqsXz5oDO2dwY_aqYwcM-_ffkzflDuzcE83/s1600/calculated_worst.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgAdwBPDC_IxUsew5rTX6EZ7kKI8mApjsZwRD-i1mYh8ZEil4hcd-XgwOb5lgN8KfHzIKIDQVHfWj2WrkhRyO1KAcoTyuHH65f60JgF7u-gRrqsXz5oDO2dwY_aqYwcM-_ffkzflDuzcE83/s1600/calculated_worst.gif" /></a></div>
<br />
Well, it's not so bad. At 55 MPH, the range is only 72 miles vs 83 miles above. At 65 MPH, the range is only 59 miles vs 66 miles above. Still, it's only about 10% worse. I can live with that if the replacement tires cost $100 less.<br />
<br />
<b>SparkEV Conclusion</b><br />
<br />
SparkEV gets about 85 miles of range per charge, but that's with new battery and without any margin. With margin, it's more like 75 miles range. Under low speed conditions, it would get far more miles per charge, as much as 140 miles at 25 MPH. For city driving and stuck in traffic, it should get much better than EPA estimate. It's simple to have longer range on SparkEV; just keep the speed low, but above 15 MPH. Using multiple DCFC sessions, even 1000 miles per day may be possible at 70 MPH or more.<br />
<b><br /></b>
<b>SparkGas theoretical analysis</b><br />
<br />
For SparkGas, major differences are weight and engine efficiency. Although SparkGas has grill opening that increases drag, we ignore that for this exercise to give benefit to gas car. What we are after is close to EPA highway MPG number of 39 MPG at 65 MPH by tweaking the engine efficiency number. Why 65 MPH? Because SparkEV's highway EPA MPGe figure matched at 65 MPH.<br />
<br />
Because gas car is so messy in terms of efficiency, not only does it vary efficiency through RPM but braking wasted as heat, highway MPG is best we can hope for in this comparison. Multiple iterations of tweaking engine efficiency to make 39 MPG at 65 MPH result in engine efficiency of 30%. Then the following parameters are used.<br />
<br />
Weight (lb): 2300 lb (google)<br />
<br />
Coeff. of rolling resistance: 0.01<br />
<br />
Drag coefficient: 0.326 (same as SparkEV, though probably worse with SparkGas)<br />
<br />
Frontal area (sq ft): 8.8 / 0.326 = 27 sq ft (same as SparkEV)<br />
<br />
Fuel energy density (Wh/gal): 33557 (summer blend drop down option)<br />
<br />
Engine efficiency: 0.3 (trial and error; see above)<br />
<br />
Drive train efficiency: 0.95 (default value)<br />
<br />
Parasitic overhead: 500 (lights are about 250 Watts, double it as guessed figure)<br />
<br />
Air density: 1.225 (default value)<br />
<div>
<br /></div>
<div>
<a href="http://ecomodder.com/forum/tool-aero-rolling-resistance.php?Weight=2300&WeightUnits=lbs&CRR=.01&Cd=.326&FrontalArea=27&FrontalAreaUnits=ft^2&FuelWh=33557&IceEfficiency=.3&DrivetrainEfficiency=.95&ParasiticOverhead=500&rho=1.225&FromToStep=5-200-5">http://ecomodder.com/forum/tool-aero-rolling-resistance.php?Weight=2300&WeightUnits=lbs&CRR=.01&Cd=.326&FrontalArea=27&FrontalAreaUnits=ft^2&FuelWh=33557&IceEfficiency=.3&DrivetrainEfficiency=.95&ParasiticOverhead=500&rho=1.225&FromToStep=5-200-5</a></div>
<b><br /></b>To save you the trouble, below is the screen shot of the table.<br />
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<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_j77E4vk7YLy64QNywIMGTmE1pIkU8nhOvFhLficruQ1vjRvJFMSCbPMLLz_Zg7qGtEII_WKmXk8cbnrn8azi6orkPGQ5WHodXHXjWBCa1KHjoddU4wNW2Vg9Gkp95077PLj_WQ9s4rxL/s1600/calculated_gas.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_j77E4vk7YLy64QNywIMGTmE1pIkU8nhOvFhLficruQ1vjRvJFMSCbPMLLz_Zg7qGtEII_WKmXk8cbnrn8azi6orkPGQ5WHodXHXjWBCa1KHjoddU4wNW2Vg9Gkp95077PLj_WQ9s4rxL/s1600/calculated_gas.gif" /></a></div>
<br />
One thing that jumps out at you is 107 MPG at 15 MPH. Yeah, this is total bogus. SparkGas will not achieve anywhere close to that. The problem is that gas engine efficiency is not a constant but varying over RPM with only a narrow range tuned for best efficiency AT FULLY OPEN THROTTLE. Typically, the maximum engine efficiency is about 75% of full power. With SparkGas having 98 HP, 75% would be about 75 HP. At that power, it would be going way over 90 MPH, probably even way over 100 MPH. While the engine efficiency might be maximum, it would get awful MPG due to aerodynamic drag.<br />
<br />
Therefore, getting meaningful theoretical data is far more difficult with gas car; one has to know the engine efficiency at particular speed (that also varies by gears). Getting that data may be possible, but I won't bother. Gas cars suck!<br />
<br />
So how do you maximize efficiency on a gas car? Fully open the throttle (minimize pumping loss) to reach maximum engine efficiency (about 75% of red line) beyond the speed limit, then shut off the engine to coast to below speed limit, then repeat. This is called "pulse and glide", a practice that should be avoided (just get an EV!)<br />
<br />
Another is to simply get smaller engine (ie, less powerful). Then it's more likely to have reasonable highway speed matched to efficient engine RPM. This is why old Geo Metro (55 HP) and new Mitsubishi Mirage (74 HP) are so efficient, but they are very boring with 0-60 MPH time of over 12 seconds. Again, just get SparkEV for maximum fun and efficiency.<br />
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<b>Hoping for SparkEV 2.0</b><br />
<br />
With GM having used up half the $7500 federal EV tax credit even before first Bolt rolls off the assembly line, it's doubtful they'll continue or expand SparkEV sales. SparkEV costs $12K less than Bolt, and even with same percentage profit margin, Bolt will make more money for GM. Having SparkEV eat into tax credit at same level as Bolt makes no sense. Well, at least that would be the bean counter's argument, which I completely understand.<br />
<br />
But I can hope and dream, can't I? Suppose there could be SparkEV 2.0, how would I go about it? Previously, I showed that longer range doesn't have to mean bigger battery. I stated SparkEV with drag coefficient of 0.15 (like 1930's prototype car) would yield close to 180 miles range while charging 140 miles in 20 minutes using existing 50 kW charger.<br />
<br />
<a href="http://sparkev.blogspot.com/2016/01/mass-market-ev-hoping-for-tesla.html">http://sparkev.blogspot.com/2016/01/mass-market-ev-hoping-for-tesla.html</a><br />
<br />
But of course, that's wrong; that ignored the rolling resistance and static power requirement. So let's explore several cases to see what is possible: Drag coefficients of 0.24 (Tesla S, Prius), 0.22 (half way between EV1 and Tesla S), and 0.15.<br />
<br />
First is the case of 0.15 to debunk my own erroneous assertion.<br />
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<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj2H8qgRqD8OkuX1BT5f4oLcKLa7daPDCCpLklfkVDbaCNrGE30OY9K5n6ukWn2P80lJRPQ12J4Y495XUwhvveZmT_JvMdswWp8d3VQPiL92520KdW8wAiOI5-TfcPJ2mFBeefrxTyQmN9l/s1600/calculated_15.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj2H8qgRqD8OkuX1BT5f4oLcKLa7daPDCCpLklfkVDbaCNrGE30OY9K5n6ukWn2P80lJRPQ12J4Y495XUwhvveZmT_JvMdswWp8d3VQPiL92520KdW8wAiOI5-TfcPJ2mFBeefrxTyQmN9l/s1600/calculated_15.gif" /></a></div>
<br />
Well, the range is only 110 miles at 65 MPH. That's about on par with 2016 Nissan Leaf's 30kWh battery, but using 19kWh battery. 55 MPH yields 130 miles, similar to what current SparkEV would get at 24 MPH. Not bad, but drag coefficient of 0.15 would take significant work.<br />
<br />
Next, let's see drag of 0.22. While this is still lower than most (all?) production cars, it may be more feasible than 0.15.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhAJj42Y-Zq7oW0L_GPsf9cqKePDwzfPVjioB-3mt0SkBTR9HmX22m4W49o_k_vsKDiKnfvOzhEo4NP45Ic6P02p7jX01V-ZIzAN1yueJcAPiE9rCAl6OAIFIFV8bd9wanLD3YbFmLPjHzS/s1600/calculated_22.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhAJj42Y-Zq7oW0L_GPsf9cqKePDwzfPVjioB-3mt0SkBTR9HmX22m4W49o_k_vsKDiKnfvOzhEo4NP45Ic6P02p7jX01V-ZIzAN1yueJcAPiE9rCAl6OAIFIFV8bd9wanLD3YbFmLPjHzS/s1600/calculated_22.gif" /></a></div>
<br />
At 65 MPH, it's only 87 miles compared to 66 miles with current SparkEV. While that's an improvement, it's nothing to get excited about. I'm not too hopeful for 0.24, something that could be if SparkEV had shape of smaller version of Tesla S.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiHPHaEs3xD7AljPWu9J3cxN36UFHd9maYpCL_9wrShHoIyoMRy00xQ6f_gCfLRPG1e_A83x0Y_Bd6rFMGAUrVify-Vsj9B_KBhqRmAcJWUOTE6-tvSOA9mdXaiWK1SGDFpzmt_RitWsYzD/s1600/calculated_24.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiHPHaEs3xD7AljPWu9J3cxN36UFHd9maYpCL_9wrShHoIyoMRy00xQ6f_gCfLRPG1e_A83x0Y_Bd6rFMGAUrVify-Vsj9B_KBhqRmAcJWUOTE6-tvSOA9mdXaiWK1SGDFpzmt_RitWsYzD/s1600/calculated_24.gif" /></a></div>
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At 65 MPH, it's only 82 miles compared to 66 miles with current SparkEV. So much for my theory that only aerodynamics is needed for significantly longer range. 55 MPH range is 101 miles. Oh well, at least it can break 100 miles freeway range by looking like a miniature Tesla S.<br />
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Still, gaining 20% range with bit of sheet metal work isn't bad. This means similar reduction in drag area (coefficient * frontal area) compared to Bolt could reduce battery size while retaining the 200 miles range. At least there's some hope for Tesla to use smaller battery with 200 miles range EV, that's good.<br />
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<b>Edit Feb. 1, 2016</b><br />
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I shrugged off discrepancy between theoretical 158 miles range at 25 MPH and actual 140 miles in experiment by hand waving that efficiency could be different. Now I have new data. I used 500 watts as a guess, but "bicycleguy" from SparkEV forums managed to extract more data using Arduino and CAN bus.<br />
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<a href="http://www.mychevysparkev.com/forum/viewtopic.php?f=10&t=4166&start=10">http://www.mychevysparkev.com/forum/viewtopic.php?f=10&t=4166&start=10</a><br />
<br />
He shows 372.32 Volts total and 3.33 Amps when "on". That would be 1240 Watts, far more than 500 Watts that I guessed. At 55 MPH power of 11 kW, 1240-500 = 740W represents 7%. That's not much off, especially considering that static power doesn't even show on power display.<br />
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For lower speeds, however, it would be significant. Using 1240 W as static power at 25 MPH, the range would be<br />
<br />
2690W + (1240W - 500W) = 3430 W<br />
17 kWh / 3.43kW = 4.96 hours, round up to 5 hours<br />
25 MPH * 5 = 125 miles<br />
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125 miles for 17 kWh usable battery on 2015 SparkEV is closer to what I estimated based on 19 kWh usable battery capacity on 2014 model.<br />
<br />
140 miles * 17 / 19 = 125.3 miles<br />
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So maybe the issue at 25 MPH range was due more to static power being different than electrical efficiency at low power levels.<br />
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For higher speed (power), static power would be less of an issue, because 0.75kW would be even smaller percentage. But motor efficiency could be different. Unfortunately, I don't have experimental data for high speed to see who far off I might be at 90 MPH, including decreased electrical efficiency. Oh well, maybe someone in Germany could import SparkEV and test it on Autobahn to see how close the theoretical values are.<br />
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Below is the new table using 1240 W as static power instead of 500 W.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjr3K7MaBpVmpGjyFo2OfD8IJV-7iQ-fVMZn0l6U85ySsUSsrdaI6j09s2PILZzUUOYudMx2nVEr3-mMNmDH3G5VAK11pDwAixXEXShNVmqtJAbpKc_vojjIyH4f4bOhF4R9ojvmu0g1Z0V/s1600/calculated_typical1.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjr3K7MaBpVmpGjyFo2OfD8IJV-7iQ-fVMZn0l6U85ySsUSsrdaI6j09s2PILZzUUOYudMx2nVEr3-mMNmDH3G5VAK11pDwAixXEXShNVmqtJAbpKc_vojjIyH4f4bOhF4R9ojvmu0g1Z0V/s1600/calculated_typical1.gif" /></a></div>
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<a href="http://ecomodder.com/forum/tool-aero-rolling-resistance.php?Weight=3000&WeightUnits=lbs&CRR=.01&Cd=.326&FrontalArea=27&FrontalAreaUnits=ft^2&FuelWh=33557&IceEfficiency=.9&DrivetrainEfficiency=.95&ParasiticOverhead=1240&rho=1.225&FromToStep=5-200-5">http://ecomodder.com/forum/tool-aero-rolling-resistance.php?Weight=3000&WeightUnits=lbs&CRR=.01&Cd=.326&FrontalArea=27&FrontalAreaUnits=ft^2&FuelWh=33557&IceEfficiency=.9&DrivetrainEfficiency=.95&ParasiticOverhead=1240&rho=1.225&FromToStep=5-200-5</a><br />
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It's only 78 miles range at 55 MPH, which is even worse in not matching experimental data of 90+ miles at 55 MPH. Oh well, the parameters are still off, but until I get better tools to measure, this is it.<br />
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<b>Edit Feb. 9, 2016</b><br />
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I normally leave 1 or 2 bars remaining before disconnecting the charger so I can regen as I'm going down the hill. Recently, I made a mistake and fully charged the car. The range showed 92 miles at Guess O Meter (GOM)!<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiT2ZYMOp-YUKUkjCasdekL9gTtIqEBctdiZgTUPwzf-m5Xwhpk5XhKGXaSm2MgLHDvmyW0j7RHItADDWFnz8eBukKNgzifezSNHabwKJH0nkMs7Qpce34j_J8C63q0A5CgX2qN4u39HuvG/s1600/range_at_7000_miles.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiT2ZYMOp-YUKUkjCasdekL9gTtIqEBctdiZgTUPwzf-m5Xwhpk5XhKGXaSm2MgLHDvmyW0j7RHItADDWFnz8eBukKNgzifezSNHabwKJH0nkMs7Qpce34j_J8C63q0A5CgX2qN4u39HuvG/s1600/range_at_7000_miles.jpg" /></a></div>
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Charging was after long drive home that was 3.8 mi/kWh. If we assume GOM bases miles on latest drive pattern, 92 miles after 3.8 miles/kWh would be usable battery capacity of 24 kWh. Obviously, this is wrong. Using 5.1 mi/kWh, battery would be 18 kWh. So maybe SparkEV uses 18 kWh out of 19 kWh? I don't know, maybe, maybe not. But 82 miles EPA could be said to be conservative estimate.<br />
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<b>Edit Feb.23, 2016</b><br />
<br />
There was a test done on 2014 SparkEV by driving in a big loop in San Diego freeway by Tony Williams (is he the same guy who owns <a href="http://quickchargepower.com/">quickchargepower.com</a>?). It was found to have 97.8 miles range (92.8 driven + 5 miles remaining) when driven at 62 MPH (100 km/hr) with 5 mi/kWh average consumption.<br />
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<a href="http://insideevs.com/real-world-test-shows-chevy-spark-ev-has-substainally-more-range-than-nissan-leaf-62-mph-wvideo/">http://insideevs.com/real-world-test-shows-chevy-spark-ev-has-substainally-more-range-than-nissan-leaf-62-mph-wvideo</a><br />
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That would make the usable battery capacity for 2014 SparkEV to be<br />
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97.8 mi / 5 mi/kWh = 19.56 kWh<br />
19.56 kWh / 21.4 kWh = 91.4% usable<br />
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This is different than 24 MPH test performed by digitaltrends (see above) where the range was 140 miles and 7.3 mi/kWh (19.19 kWh, 89.6% usable). What this points to is that there could be substantial (under 2% is substantial?) difference in range and expected battery capacity. But it's only two samples, so the actual variability is unknown.<br />
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Tony also did a similar test using 2015 SparkEV, and found the range to be less, though still much longer than EPA figure. He wrote "shhhh", so you have to search for it yourself if you want to know the actual value. It's actually less than my 55 MPH test (85 miles with 9 miles remaining = 94 miles)<br />
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My 2015 SparkEV was getting "roughly" 5 mi/kWh when driven at 55 MPH, though I did not record the number after the trip was over. Due to different gearing, it's possible that 2015 SparkEV is bit less efficient at highway speed than 2014 model (higher motor RPM). In addition, 2015 has 18.4 kWh (some say 18.3 kWh) battery instead of 21.4 kWh of 2014 model.<br />
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This COULD make the range on 2015 SparkEV to be less than 2014 model WHEN BOTH ARE NEW. I have to stress "COULD" and "NEW", because the batteries are made by different vendors, LG for 2015 model, and A123 for 2014 model. The way different battery chemistries perform as well as aging would make the comparison difficult today. Suffice it to say, using the low figure of 2015 range is a good conservative estimate; if the range is exceeded, it'd be a pleasant surprise rather than the other way around.<br />
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There was also some speculation that 2015 SparkEV uses far more percentage of battery than 2014 model. Some speculate as much as 100%. The range of 92 miles from my recent 100% charging session is consistent with this speculation (18 kWh / 18.4 kWh = 98%). However, going by GOM (guess-O-meter) is not entirely accurate.<br />
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Below is a summary table of range in miles for various "simulation" models. First column is using 17 kWh and low rolling resistance tires, the first table I have above (Crr=0.01, 90% efficient, 500W static power). Second column is the same with Crr=0.015 and 80% efficiency (second table from above). Third column is the same as first column with 1240W as static power. Fourth column is the same as first column using 18.4 kWh as usable battery capacity. Fifth column is the same as third column (1240W static power) using 18.4 kWh as usable battery capacity.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgm3G2NpMPeJGxF5miMcCiC5OJsimC-1T7cTpdfCuRIXWshgCyVgoL9XDt2M6Y6LNullU1a_yJ87zqgoUMYAKuIQye0jeCPHxt9LyPg_htzzL2sTbSTCMhXQgh0IVvA4EZSOXERdD7UWhQ2/s1600/range_summary.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgm3G2NpMPeJGxF5miMcCiC5OJsimC-1T7cTpdfCuRIXWshgCyVgoL9XDt2M6Y6LNullU1a_yJ87zqgoUMYAKuIQye0jeCPHxt9LyPg_htzzL2sTbSTCMhXQgh0IVvA4EZSOXERdD7UWhQ2/s1600/range_summary.gif" /></a></div>
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Green highlights the closest to data I obtained using 55MPH. I could actually go for 4 more miles, so even this is a conservative estimate WITH NEW BATTERY.<br />
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Last columns are average and standard deviation. After all, central limit theorem says it (estimates) will all turn Gaussian eventually, I just skip the middlemen and use only 5 samples (it's a math joke). Because static power and other "issues" would play a bigger role at lower speeds, one should expect large variability at low speeds; turn off your lights and the radio to maximize efficiency at low speeds.<br />
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Some ask what the worst case range might be. With windows open, AC, heat, stereo, all of them at full blast, worst case is hard to define. Heat could be substantial in very cold weather (4kW all the time = 20% cut in range). One could have inefficient winter tires + heat + open the window for maximum energy waste. The battery could also have been abused so the capacity is far less. One could be stuck in dead-stop traffic for hours using static power (radio + heat/AC) without actually moving. Without knowing the parameters, it's impossible to say what the worst case range might be. Well, I guess we know: worst case is 0 miles range.<br />
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More reasonable case is to go by average figure as relatively safe estimate when operating on flat road with windows closed and no heat / AC. With a new battery, windows down and even little bit of AC or heater use would be in range. However, always leave few miles (I use 10 miles) as a buffer to be able to get to a charger in case the intended charger is out of order. As the EV gets older, it will have degraded battery, so the range should be derated appropriately.<br />
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And, of course, a pretty little plot of the data table, too.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiWZvhL8aVlLXLLu4p7TOsxVTnoEJDdvA3im8SOieWIrbB_9QY2Xs6WWmGuajAMsObOXeAt0sBKDegHkVlqchlzbSIjMWVk-WoZ_y4Y6Hq9jUlDdcTijVR4F5cpHF08cibZs50OIli80_Bl/s1600/range_summary_graph.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiWZvhL8aVlLXLLu4p7TOsxVTnoEJDdvA3im8SOieWIrbB_9QY2Xs6WWmGuajAMsObOXeAt0sBKDegHkVlqchlzbSIjMWVk-WoZ_y4Y6Hq9jUlDdcTijVR4F5cpHF08cibZs50OIli80_Bl/s1600/range_summary_graph.gif" /></a></div>
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<br />sparkevhttp://www.blogger.com/profile/04362518920979349841noreply@blogger.com12tag:blogger.com,1999:blog-6875771813122616391.post-79665535588130767752016-01-17T20:55:00.000-08:002016-02-25T11:19:01.948-08:00Mass market EV, hoping for Tesla<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj7HHcOyIoNcqAohrxIYu7HVgFVKHfb5FaHKMtTs3O6EeRzHrd3HO08ZLHmn2JHOQSHhJI2lG9ukJmMyWVRZl-0W4AwzY0_Ae9qbpx7O6suB-ouM7ZdzpkkIqj_OwqdHLybElpi5d0IYF2H/s1600/tesla-motors-logo-smart-planet-1.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj7HHcOyIoNcqAohrxIYu7HVgFVKHfb5FaHKMtTs3O6EeRzHrd3HO08ZLHmn2JHOQSHhJI2lG9ukJmMyWVRZl-0W4AwzY0_Ae9qbpx7O6suB-ouM7ZdzpkkIqj_OwqdHLybElpi5d0IYF2H/s1600/tesla-motors-logo-smart-planet-1.gif" /></a></div>
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<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;">Previously, I griped about shortcomings of Chevy Bolt.</span></span><br />
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<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;"><a href="http://sparkev.blogspot.com/2016/01/mass-market-ev-to-bolt-or-not-to-bolt.html">http://sparkev.blogspot.com/2016/01/mass-market-ev-to-bolt-or-not-to-bolt.html</a></span></span><br />
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<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;">Chevy still has time to make it better. One would be to make the power 250 HP or more. This may be relatively easy as the 250 HP would only be used for brief burst in acceleration, not sustained.</span></span><br />
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<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;">The other is to make DCFC chargers and help expand the network. Although Chevy stated they won't do anything unless it benefits all their customers, which I read to mean gas cars, they can still change their mind. I mean, Bolt is capable of 150kW charging (3X larger battery than SparkEV), don't they want to test it? Then the test fixture can be made as commercial charger and sold or leased. Isn't there any engineering curiosity, like the guy who made world's fastest lighting BBQ?</span></span><br />
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<span style="background-color: white; color: #222222; line-height: 18.48px;"><a href="http://www.davebarry.com/misccol/charcoal.htm">http://www.davebarry.com/misccol/charcoal.htm</a></span><br />
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<span style="background-color: white; color: #222222; font-family: inherit; line-height: 18.48px;">Chevy chose to have large battery for range. At 60kWh, it would cost $12,000 (+ labor) to replace it if the pack costs $200/kWh (cell is supposed to be $145/kWh today). Even at $100/kWh, that works out to over $6000+labor when the battery dies after 10+ years. People aren't likely to spend that much money to repair an old car, especially one that performs poorer than comparable gas cars, such as Subaru WRX that comes with AWD and has more power. On top of that, Bolt takes close to an hour to get 80% (160 miles) range. Bolt is pretty much a disposable car.</span><br />
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;"><br /></span></span>
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;"><b>Model killing Bolt</b></span></span><br />
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;"><br /></span></span>
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;">Then there's another coming: Tesla Model3. While 0-60 performance kicking butt of every car in its price range would be nice, there are two other important metric: range and DCFC time.</span></span><br />
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;"><br /></span></span>
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;">What's needed is smaller battery that achieves same range as Bolt and higher power charging. Tesla already has higher power charging: 120kW supercharger network. Assuming no taper to 80% like SparkEV, 15 minutes of charge would be 30 kWh. That needs to have range of 160 miles (80%). Then the total battery capacity would be 37.5 kWh, or round up to 40 kWh (or bit more for margin). </span></span><br />
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;"><br /></span></span>
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;">At $200/kWh pack price, Model3 could be $4000 cheaper than Bolt. After 10+ years when battery prices have come down to $100/kWh, it would be $2000 cheaper. While $4000+labor isn't chump change, it is more palatable than $6000+labor for Bolt, especially if Tesla charges in 15 minutes.</span></span><br />
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;"><br /></span></span>
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;">The range on EV is primarily the freeway range. I will cover EV range in more detail in later post, but EV is fairly simple to characterize in that faster you go, the lower the range. What's needed is 160 miles at 65 MPH using 30 kWh (or 200 miles using 37.5 kWh), or 160/30 = 5.33 mi/kWh from battery to wheels.</span></span><br />
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;"><br /></span></span>
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;">Is it possible? Yes, of course! SparkEV does between 5 mi/kWh and 5.5 mi/kWh at 55 MPH with its enormous height and awful drag coefficient (0.326 vs Prius 0.28). If Tesla can keep the drag down, it can get away with smaller battery and achieve 15 minutes for 160 miles with their existing Supercharger network. Exact drag also depends on the frontal area, but if Tesla can achieve under 0.2 drag coefficient (EV1 was 0.19), it's probably enough.</span></span><br />
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;"><br /></span></span>
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;">On top of that, smaller battery would be lighter. Bolt battery is 960lb for 60kWh, and assuming same energy weight density, 40 kWh would be 320lb lighter at 640lb. That will reduce rolling resistance, further help in range.</span></span><br />
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;"><br /></span></span>
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;">Lighter battery would also help in acceleration. Tesla's old 40kWh Model S had 235 HP motor. Combined with lighter than Bolt by about 320lb (3200 lb) that would put it in league of comparable cost gas cars in lb/hp (13.6 lb/hp, better than Fiesta ST). But for 0-60 time, it should be far quicker than gas cars, probably under 6 seconds, maybe even reaching 5 seconds.</span></span><br />
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;"><br /></span></span>
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;">EV that does 0-60 close to 5 seconds, 15 minutes to charge 160 miles range, cost about $26K (or $24K in CA), extremely efficient aerodynamics (ie, less noise), now THAT is a kick ass mass market EV I'd be proud to own. Come on Tesla! Let's do this!</span></span><br />
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;"><br /></span></span>
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;"><b>Edit Jan. 19, 2016</b></span></span><br />
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;"><br /></span></span>
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;">It seems some have doubts as to what I'm saying. Firstly, unless there's a revolution in battery technology (ie, not Lithium), price is expected to be about $100/kWh. It's also true that few people spend several thousand dollar upfront to fix an old car, especially poor people who tend to drive older cars. Then they'll continue to drive gas guzzling and high pollution cars. In case of pollution, we're not just talking about CO2, but immediately harmful stuff like sulfur oxides, CO, HC, NOx.</span></span><br />
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;"><br /></span></span>
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;">The aerodynamics I propose here is not a new idea. From Wikipedia, we can see several cars that have very low drag coefficient.</span></span><br />
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;"><br /></span></span>
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; color: #222222; line-height: 18.48px;"><a href="https://en.wikipedia.org/wiki/Drag_coefficient">https://en.wikipedia.org/wiki/Drag_coefficient</a></span></span><br />
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; color: #222222; line-height: 18.48px;"><br /></span></span>
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;"><span style="line-height: 18.48px;">Limited cars like EV1 has 0.19 and VW XL1 of 2014 has 0.186. </span>While some look comical, Prius has 0.25 (0.24 for 4th gen) while far better looking Tesla Model S has 0.24. Better aerodynamics doesn't have to mean weird.</span></span><br />
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;"><br /></span></span>
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;">By far the most impressive is Schlorwagen from 1939 that had drag coefficient of 0.15. </span></span><span style="background-color: white; color: #222222; line-height: 18.48px;"><strike>If SparkEV has such drag coefficient while retaining current specs (frontal area, weight, battery, etc), it would get about 180 miles range, and charge 144 miles in 20 minutes using 50 kW charger (range using EPA figures)</strike> (WRONG! While there will be improvement, I ignored rolling resistance. See EV range blog post in the future for better data). This is only with sheet-metal work, nothing to do with battery.</span><br />
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;"><br /></span></span>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://upload.wikimedia.org/wikipedia/commons/thumb/3/3f/Schl%C3%B6rwagen.jpg/640px-Schl%C3%B6rwagen.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://upload.wikimedia.org/wikipedia/commons/thumb/3/3f/Schl%C3%B6rwagen.jpg/640px-Schl%C3%B6rwagen.jpg" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">https://en.wikipedia.org/wiki/Schl%C3%B6rwagen</td></tr>
</tbody></table>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;">From the looks of it, it's not conventional looking by the standard of its day. But it's something sort of, kind of looks like what could appear today or in near future. While conventional gas engine did not allow for much flexibility, battery technology can allow far more flexibility in shaping car's body for aerodynamics. For example, there is no poisonous gas coming from the engine that you need to seal off completely from passenger compartment.</span></span><br />
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;"><br /></span></span>
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;">When it comes to Chevy type of battery, they are cube blocks. But Tesla uses thousands of 18650 batteries that are typical of laptops. Arranging them in odd shape to have a body shape that minimize drag is far easier. Of course, this assumes Tesla will do such simple minded optimization. They could come up with entirely new way to do things.</span></span><br />
<br />
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;">But one thing that I hope Tesla doesn't do is brute force: stick ever larger large battery in EV approach. In short term, that'll cost more, weigh more, making it uncompetitive to comparable gas cars. In long term, that'll add to more waste at junk yard and not as many poorer people driving old, used EV, instead driving really hazardous polluting old gas guzzlers.</span></span><br />
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;"><br /></span></span>
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;"><b>Edit Jan. 29, 2016</b></span></span><br />
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;"><br /></span></span>
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;">After doing "SparkEV range" post, there are few interesting findings using ecomodder web site.</span></span><br />
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; line-height: 18.48px;"><br /></span></span>
<span style="color: #222222; font-family: inherit;"><span style="background-color: white; color: #222222; line-height: 18.48px;"><a href="http://sparkev.blogspot.com/2016/01/sparkev-range.html">http://sparkev.blogspot.com/2016/01/sparkev-range.html</a></span></span><br />
<ol>
<li><span style="color: #222222;"><span style="line-height: 18.48px;">SparkEV EPA range roughly corresponds 55 MPH range.</span></span></li>
<li><span style="color: #222222;"><span style="line-height: 18.48px;">SparkEV EPA highway MPGe is roughly 65 MPH MPG.</span></span></li>
<li><span style="color: #222222;"><span style="line-height: 18.48px;">SparkEV uses 90% of battery capacity.</span></span></li>
</ol>
First point is quite important. I wanted 65 MPH for range, but the EPA seem to use 55 MPH for SparkEV. That's much easier than 65 MPH. Power is proportional to speed cubed. It's also true that Tesla S has 0.24 drag coefficient as tested by third party.<br />
<br />
<a href="http://www.greencarreports.com/news/1092373_aerodynamic-tesla-model-s-electric-car-wins-the-wind-tunnel-wars">http://www.greencarreports.com/news/1092373_aerodynamic-tesla-model-s-electric-car-wins-the-wind-tunnel-wars</a><br />
<br />
<b>Tesla S60 model</b><br />
<br />
I know SparkEV parameters, and actual experimental data (that I conducted), but I don't have first hand knowledge of Tesla with respect to power vs speed. Still, we can use ecomodder web site using known data to see what turns up. I start with SparkEV parameters, and change the weight to 4323 lb (Wikipedia S60), Cd to 0.24, frontal area to 25.8 (greencarreports).<br />
<br />
Knowing that 65 MPH returns roughly the highway MPGe with SparkEV, we can tweak Tesla S parameters until 65 MPH is 97 MPG. Weight and drag and area are fixed to S60 specific data. I use 75% for motor and 90% for drive train and 1000 W for parasitic overhead (for giant 17 inch display?). Rest are kept the same. This results in 96.7 MPG at 65 MPH.<br />
<br />
<a href="http://ecomodder.com/forum/tool-aero-rolling-resistance.php?Weight=4323&WeightUnits=lbs&CRR=.01&Cd=.24&FrontalArea=25.8&FrontalAreaUnits=ft^2&FuelWh=33557&IceEfficiency=.75&DrivetrainEfficiency=.9&ParasiticOverhead=1000&rho=1.225&FromToStep=5-200-5">http://ecomodder.com/forum/tool-aero-rolling-resistance.php?Weight=4323&WeightUnits=lbs&CRR=.01&Cd=.24&FrontalArea=25.8&FrontalAreaUnits=ft^2&FuelWh=33557&IceEfficiency=.75&DrivetrainEfficiency=.9&ParasiticOverhead=1000&rho=1.225&FromToStep=5-200-5</a><br />
<br />
Greencarreports states Tesla S would use 14 HP at 70 MPH, but the table shows that's only to overcome aerodynamics. Since the article was with respect to drag, I think the data I have is correct.<br />
<br />
<b>Guess for Model 3</b><br />
<br />
Using the data from Model S, we reduce the weight to 3200 lb (320 lb lighter than Bolt by using 40 kWh battery instead of 60 kWh 960 lb battery). There's some speculation that Model 3 will be 80% the size of S. Given that S is pretty wide, I guesstimate about 90% width (frontal area) as 23.5 sq ft.<br />
<br />
The number we are looking for is power at 55 MPH, the number that matches EPA range for SparkEV, and we'll use that number to validate if 40 kWh battery is big enough to achieve 200 miles range.<br />
<br />
<a href="http://ecomodder.com/forum/tool-aero-rolling-resistance.php?Weight=3200&WeightUnits=lbs&CRR=.01&Cd=.24&FrontalArea=23.5&FrontalAreaUnits=ft^2&FuelWh=33557&IceEfficiency=.75&DrivetrainEfficiency=.9&ParasiticOverhead=1000&rho=1.225&FromToStep=5-200-5">http://ecomodder.com/forum/tool-aero-rolling-resistance.php?Weight=3200&WeightUnits=lbs&CRR=.01&Cd=.24&FrontalArea=23.5&FrontalAreaUnits=ft^2&FuelWh=33557&IceEfficiency=.75&DrivetrainEfficiency=.9&ParasiticOverhead=1000&rho=1.225&FromToStep=5-200-5</a><br />
<br />
65 MPH shows 113 MPG, even better than SparkEV highway MPGe (aka, efficiency). 55 MPH shows 9.3 kW. That's 15% better than SparkEV! Let's just make it 9.6 kW, what the heck. Why 9.6? If you have to ask, you won't like the answer!<br />
<br />
Now let's see if 40 kWh will be enough to get 200 miles range. Recall that I wanted 30 kWh for 160 miles range (80% of 200 miles) so it can be charged in 15 minutes using 120 kW supercharger without taper. 3 hours at 55 MPH is 165 miles, close enough to 160 miles. Then the energy needed would be<br />
<br />
9.6 kW * 3 hours = 29 kWh (oooohhh!)<br />
<br />
This meets my requirement with margin to spare. Energy needed for 200 miles range would be<br />
<br />
29 kWh / 165 miles * 200 miles = 35.15 kWh (aaahhh!!)<br />
<br />
From various experiments, SparkEV is using 90% of battery capacity. From some forum posts, Leaf also uses 90% (22 kWh out of 24 kWh battery). Forum posts? Yeah, it could be garbage, but it sounds plausible from other users' findings as well. Then the battery should be<br />
<br />
35.15 kWh / 0.9 = 39 kWh (WOW!!! I'm a genius!)<br />
<br />
In effect, what this suggests is that Tesla could be building miniature Model S using 40 kWh battery and calling it mass market EV at lower cost than Bolt. What I wrote above could be a reality with very little design effort from Tesla. That's great news! Where do I buy one?<br />
<br />
<b>Keeping up with Teslas</b><br />
<br />
Yeah, only if life is that simple. Tesla may not use 90% of battery capacity like SparkEV and Leaf. In fact, some forum posts say it could be as low as 70%. Let's check that with known numbers. SparkEV has EPA range of 82 miles. S60 has 3 times bigger battery. They have roughly similar power requirement at 55 MPH. Then the range for S60 should be 3 times that of SparkEV at 248 miles. Clearly, that isn't the case as EPA rates S60 at 208 miles.<br />
<br />
But let's go the other way. S60 is 11 kW at 55 MPH with 60 kWh battery. To use all 60 kWh, the range would be<br />
<br />
55 MPH * 60 kWh / 11 kW = 300 miles<br />
<br />
70% of 300 miles is 210 miles. It seems Tesla is indeed using only 70% of full battery capacity. Let's see where it takes us with our Model 3 guess if 70% is used instead of 90%.<br />
<br />
35.15 kWh / 0.7 = 50 kWh (ooops!!!!)<br />
<br />
It's better than 60 kWh, but 50 kWh is still too high. Of course, most of these values are guesses. Tesla probably can make 40 kWh EV with 200 miles range as mini Model S, but the reliability (ie, range degradation) may not be up to their standard. But if mass market means bit more range degradation, they can relax their standard a bit. One might say "keeping up with Teslas, but not the high end"<br />
<br />
Perhaps they can offer various battery options like they do with Model S. Then using 40 kWh battery while keeping 70% battery utilization would result in range of<br />
<br />
40 kWh * 0.7 = 28 kWh<br />
55 MPH / 9.6 kW *28 kWh = 160 miles<br />
<br />
While it's not quite 200 miles range, 160 miles range is probably good enough for more than 2 hours at 65 MPH.<br />
<br />
But what I'm after is 80% to be able to charge at full 120kW power without taper. 80% of 160 miles would be 128 miles. 128 miles is good for about 2 hours of driving in freeway, though it'll probably be 60 MPH. Combine that with less than 15 minutes to charge, that would still make for very compelling mass market EV, especially if the price is lower by thousands of dollars compared to 60 kWh Bolt.<br />
<br />
But as I wrote above, I hope they don't just stick with large battery for range whatever they do. Brute force is not an elegant solution to engineering problems.<br />
<br />
<b>Edit Feb. 25, 2016</b><br />
<br />
It seems ecomodder web site only uses motor efficiency for MPG figure, not the power in kW. Then the above analysis using power is wrong (oops!) One should use MPG column. Using 134.4 MPGe at 55 MPH,<br />
<br />
134.4 MPG / 33.557 kWh/gal = 4.0 mi/kWh<br />
4 mi/kWh * 60 kWh * 0.8 = 192 miles (60 * 0.8 / 120 = 0.4 hours, 24 minutes for 80% of 60 kWh)<br />
4 mi/kWh * 40 kWh * 0.8 = 128 miles (40 * 0.8 / 120 = 0.27 hours, 16 minutes for 80% of 40 kWh)<br />
<div>
<br />
Those would be roughly EPA's rated range. More usable is 65 MPH range. Using 113 MPGe at 65 MPH,<br />
<br />
113 MPG / 33.557 kWh/gal = 3.37 mi/kWh<br />
3.37 mi/kWh * 60 kWh * 0.8 = 162 miles (24 minutes charging)<br />
<span style="font-family: 'times new roman';">3.37 mi/kWh * 40 kWh * 0.8 = 108 miles (16 minutes charging)</span></div>
<div>
<br /></div>
<div>
Huge oops!</div>
<div>
<br /></div>
<div>
However, that was assuming motor efficiency of 75%, something they may be able to improve upon for lower performance than Model S. At 90% efficiency, 65 MPH shows 136 MPG. Then 40 kWh range would be similar to 55 MPH case above. 128 miles using 80% of battery at 65 MPH is almost 2 hours of driving. That's quite satisfactory for almost all cases, especially if it allows 16 minutes to charge and cheaper by thousands of dollars than Bolt.</div>
sparkevhttp://www.blogger.com/profile/04362518920979349841noreply@blogger.com1tag:blogger.com,1999:blog-6875771813122616391.post-29598067506232436632016-01-14T21:24:00.001-08:002016-01-17T20:32:42.984-08:00Mass market EV, To Bolt or not to Bolt<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjUn2JmKx5Xr4wF95DkRhNDFad09MOl8I7OqI6yk4iq-s7m-3S2xgSAQQY4IuZtkoS-z16t0RB9E7pugeEF4xdwBBpUCM8OKOpScHoq0pIwR7LHZ8cb0fQ9IcRvKo_PsdFsGJOjkpZmKDSC/s1600/bolt.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjUn2JmKx5Xr4wF95DkRhNDFad09MOl8I7OqI6yk4iq-s7m-3S2xgSAQQY4IuZtkoS-z16t0RB9E7pugeEF4xdwBBpUCM8OKOpScHoq0pIwR7LHZ8cb0fQ9IcRvKo_PsdFsGJOjkpZmKDSC/s1600/bolt.jpg" /></a></div>
<br />
<br />
Chevy announced Bolt to the public long ago, but the details have been lacking until recently. At 2016 CES, they announced that the battery will be 60 kWh, giving it a range of 200 miles. At NAIAS (North America International Auto Show), they announced further details. Curiously, Chevy's Bolt web site doesn't list performance figures, but only that it's 200 miles range EV and 9 hours to charge, and doesn't even mention fast charge using CCS.<br />
<br />
<a href="http://www.chevrolet.com/bolt-ev-electric-vehicle.html">http://www.chevrolet.com/bolt-ev-electric-vehicle.html</a><br />
<br />
Did Chevy forget that it's a car company, and not a electric-thing-a-ma-jig company? While SparkEV prominently lists horsepower and torque, Bolt power number is buried deep while they drone on about connectivity, something that even $10 cell phones have nowadays. So deep, in fact, that power is not even mentioned on its main website. While Nissan Turtle (oops, I mean Leaf) or Mitsubishi Snail (I mean iMiev, one of the slowest cars on the road) can get away with slow as molasses EV by claiming that they get the best range in their class, a car company that makes Corvette and SparkEV shouldn't be ashamed / hide its car's performance.<br />
<br />
Digging further, I found the spec here.<br />
<br />
<a href="http://media.chevrolet.com/media/us/en/chevrolet/home.detail.html/content/Pages/news/us/en/2016/Jan/naias/chevy/0111-bolt-du.html">http://media.chevrolet.com/media/us/en/chevrolet/home.detail.html/content/Pages/news/us/en/2016/Jan/naias/chevy/0111-bolt-du.html</a><br />
<br />
Some key figures:<br />
<br />
200 horsepower, 266 ft-lb of torque<br />
60 kWh battery<br />
90 miles charging in 30 minutes using CCS<br />
50 miles charging in 2 hours (25 miles per hour, 7.2kW L2)<br />
3580 lb (960 lb battery)<br />
0-60 under 7 seconds (how low? we don't know yet)<br />
0-30 in 2.9 seconds<br />
$30,000 after subsidy (probably $37,500 MSRP)<br />
<br />
<b>Great EV performance</b><br />
<br />
One obvious performance figure worse than SparkEV is the torque. While SparkEV was 400 ft-lb in 2014 and 327 ft-lb in 2015, key figures prominently displayed at Chevy's SparkEV web site, 266 ft-lb is much less than SparkEV. But the power is more than SparkEV, so that's good, right?<br />
<br />
3000lb / 130HP = 23 lb/HP (SparkEV)<br />
3600lb / 200HP = 18 lb/HP (Bolt)<br />
<br />
As far as EV's go, Bolt has far better weight to power ratio than anything in its price range.<br />
<br />
0-60 time isn't known other than "under 7 seconds". Assuming 6.5 sec and 6.9 sec for 0-60, using my "range-performance-cost" metric from my previous EV ranking post,<br />
<br />
<a href="http://sparkev.blogspot.com/2015/09/ev-ranking.html">http://sparkev.blogspot.com/2015/09/ev-ranking.html</a><br />
<br />
200 miles / 6.5 sec / 30 * 1000 = 1026<br />
<div>
200 miles / 6.9 sec / 30 * 1000 = 966</div>
<div>
<br /></div>
Those scores are better than all EV, including Tesla. If you're in the market for an EV and only EV, and you have $30K to spare, Bolt is the clear choice, at least for now; let's see how Tesla Model 3 does later in the year. It only costs $4K more than Leaf with 110 miles range / 0-60 in ~10 sec. In fact, it may perform even better than BMW i3 while costing less and 2.5 times the range.<br />
<br />
Bolt is a winner? Not so fast.<br />
<br />
<b>Underpowered</b><br />
<br />
I got excited about SparkEV and people get excited about Tesla P90DL, because they are better performing than all cars in their price range, not just EV. I can't get excited about cars that perform poorer than comparably priced gas cars. For example, Leaf with its 0-60 in 10 sec was quickest EV in its price range when it first came out (against cars like Zap!), but it was one of the slowest cars in its price range. That's not something to get excited about. It just reinforces the stereotype that EV is over priced, under performing glorified golf cart.<br />
<br />
At first glance, Bolt suffers the same as Leaf. Compared to gas cars of about $30K, Bolt seem to be highly lacking. Below table shows how comparably priced gas cars perform from car and driver web site. As usual in my blog post, yellow (jersey like in bicycle race) highlights the best.<br />
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As you can see, Bolt drops to bottom of the pack of comparable cost cars when it comes to weight to power ratio. Well, that sucks. It would seem Bolt is a dud. But who cares if a car makes 1 lb/hp? What matters is 0-30 and 0-60 time with respect to price, because that's what's most used in everyday driving: traffic light show off and merging in freeway. Like EPA's MPGe, lb/hp has little meaning when it comes to real world performance.<br />
<br />
<b>Slow 0-30 times</b><br />
<br />
Often, EV folks crow about quick 0-30 mph times of EV due to "instant torque". Here, the numbers are difficult to find for gas cars, but Bolt spec shows 2.9 seconds. Well, that SUCKS! SparkEV does it in about 3 seconds, and it's $12K cheaper. Far more importantly, gas cars of comparable cost perform better.<br />
<br />
<a href="http://www.caranddriver.com/comparisons/2015-volkswagen-gti-vs-2013-ford-focus-st-final-scoring-performance-data-and-complete-specs-page-4">http://www.caranddriver.com/comparisons/2015-volkswagen-gti-vs-2013-ford-focus-st-final-scoring-performance-data-and-complete-specs-page-4</a><br />
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VW GTI is listed as 2.2 seconds ($29.5K). Ford Focus ST is listed at 2.4 seconds ($31K). As far as "drag race" at stop light to stop light against comparable cost cars, Bolt loses by wide margin.</div>
<b><br /></b>
<b>0-60 time-price product</b><br />
<br />
Better metric for comparison is 0-60 with pricing as consideration. However, Chevy doesn't list the time for 0-60, only that it'll be under 7 seconds. Then we're left to guess. I guesstimate 6.75 seconds. Though SparkEV is not in competition, it's highlighted in green.<br />
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Once again, Bolt is at the bottom. What's embarrassing is Bolt performs poorer than all gas cars in 0-60, including Fiesta ST that cost $7500 less! Bolt would be a loser if 0-60 is more than 6 seconds (only slower than GTI, WRX that cost $2500 less), though 5 seconds would barely make it a winner.<br />
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As before in EV ranking, I square the 0-60 time to give advantage to higher cost quicker cars. Even then, Bolt comes in at dead last.<br />
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<b>5-60 time-price product</b><br />
<br />
What's strange about car and driver is that they list many different figures for acceleration. For some cars, they use method somewhat like my "slip the clutch" acceleration. Using this method would surely yield best 0-60 times for gas cars. Indeed, such method could allow stock Corvette to beat Tesla P90DL in 0-60 time as I describe in my previous blog post. Neener neener to those who thought gas cars can't have peak torque from 0 MPH!<br />
<br />
<a href="http://sparkev.blogspot.com/2015/11/can-stock-corvette-beat-tesla-p90dl-in.html">http://sparkev.blogspot.com/2015/11/can-stock-corvette-beat-tesla-p90dl-in.html</a><br />
<br />
But that's not what people would do in terms of everyday driving in merging to freeway. They'd engage the clutch as soon as possible to minimize clutch wear and allow the engine power at appropriate RPM to accelerate. Such metric seem to be what car and driver calls "5-60 rolling start". Because Bolt would (should?) have close to max torque available at start, starting at 5 mph would yield lower time than 0-60, so I guesstimate 6.5 seconds for this comparison.<br />
<br />
Car and driver also list many different prices: main price in bold, base price, and tested price. Tested price is with many options that may or may not have to do with acceleration. But it's impossible to separate them out, so I use tested price for comparison. This will give advantage to Bolt.<br />
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Well, well! Bolt isn't so bad after all! In fact, acceleration would be right in the middle of the pack between WRX and Ford Focus ST, though WRX has all wheel drive. When 5-60 time is squared, Bolt comes in between WRX and Fiesta ST, though Fiesta ST is lot cheaper. Oddly, Subaru WRX STi is slower than WRX while it has more power. Maybe the gearing isn't optimized for 5-60 runs, who knows?<br />
<br />
An interesting side note is that SparkEV at $15K in CA ($26K - 7.5K(fed) - 2.5K (CA) - 1K( Chevy has $1K discount going on)) would perform better than Fiesta ST that cost $10K more, and close to Focus ST that's double the cost. Even though the time used for SparkEV is 0-60, and not lowered like with Bolt, SparkEV comes out at top even after squaring the time.<br />
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<b>Performance assessment</b><br />
<br />
I'm guessing Bolt's 0-60 times, and it's hard to know how much cost was involved in extras not related to performance for comparably priced gas cars, so 5-60 is probably the best case for Bolt. It's not the best of the pack, but not the worst. When it comes to bragging rights for 0-30 and 0-60, Bolt would probably lose when gas cars employ "ride the clutch" acceleration method. But when it comes to everyday driving, Bolt would be in the middle of the pack of comparable cost gas cars.<br />
<br />
Or is it? Remove Ford from the list, and Bolt guesstimate again drops to the bottom of the pack in terms of absolute 5-60 time. What's saving it from being the bottom with respect to 5-60 price product would be the federal tax credit. Since most people will take the tax credit, Bolt is still not too bad, though not at the top of the game like SparkEV.<br />
<br />
As a successor to SparkEV, that's an embarrassment. SparkEV is quicker than all gas cars of comparable cost. It's even quicker than cars that cost $10K more, and almost as quick as gas cars that cost twice as much, Fiesta ST and Focus ST, respectively. I guess one reason might be that Ford sucks. But the real reason would be that Chevy engineers did one hell of a job with SparkEV, but only so-so job with Bolt.<br />
<br />
<b>Slow charging</b><br />
<b><br /></b>
As I mentioned above, Chevy's main Bolt web site doesn't even list fast charging information. WTF? Unlike gas cars, people are unaware that they can "fuel" EV using fast charge and drive many times the battery range in a day. Highlighting 9 hours charge time as if that's something to be proud of is to say "don't buy Bolt; it sucks!"<br />
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From other sources, we can glean few things from this. 9 hours for 60 kWh battery is 6.66 kW. Spec shows 7.2kW. But that could be a problem for some (many?) people. At 7200W / 240V = 30A. This is significant current that may require special wiring at home. SparkEV's 16A was far easier on house wiring as many (most? all?) wall sockets wiring can accommodate the current. I suspect some (many?) will be in for a surprise when they find out that their home needs wiring upgrade or they have to use 3.3kW EVSE and take close to 20 hours to charge.<br />
<br />
Far more important and far, far worse is DCFC speed. At 90 miles per 30 minutes, that seems to be 50kW charger. To get 80% of 200 miles (160 miles) would need<br />
<br />
160 / 90 * 30 = 53 minutes!<br />
<br />
In contrast, SparkEV would reach 80% in 20 minutes. If people only charge to X miles just to get to their destination, Bolt is fine. But human psychology is such that they look for X%, not X miles. Waiting almost an hour at DCFC is pretty sad. Chevy went from being the quickest charging EV in the world with SparkEV to slowest charging EV in the world with Bolt.<br />
<br />
<a href="http://sparkev.blogspot.com/2015/12/sparkev-is-quickest-charging-ev-in-world.html">http://sparkev.blogspot.com/2015/12/sparkev-is-quickest-charging-ev-in-world.html</a><br />
<br />
I only discuss DCFC as I consider non-DCFC as toys, not real vehicles.<br />
<br />
Of course, it doesn't have to be this way. CCS is rated to 170kW. At 3 times the battery of SparkEV, 150kW charger would put the Bolt back in the game as one of the quickest, if not the quickest charging EV in the world. I'm pretty sure Chevy has the engineering talent to pull it off. But alas, Chevy doesn't seem to care about this very important aspect of EV, which is fast charging.<br />
<br />
<a href="http://www.greencarreports.com/news/1101774_gm-wont-fund-ccs-fast-charging-sites-for-2017-chevy-bolt-ev">http://www.greencarreports.com/news/1101774_gm-wont-fund-ccs-fast-charging-sites-for-2017-chevy-bolt-ev</a><br />
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So Bolt will be the slowest charging EV in the world. Sometimes, I feel like taking over Chevy and slap some sense into them.</div>
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<b>Would I buy Bolt?</b><br />
<br />
In a word, no. While Bolt isn't bad in 0-60, it's not great. After SparkEV, I've come to expect greatness from EV, not just merely "ok". Settling for Bolt just because it's an EV when better gas cars (performance and/or space, towing, convenience) at comparable or lower prices are available doesn't make sense to me. It's like, well, buying a Nissan Leaf: EV turtle.<br />
<br />
Even worse, $30K is significant amount of money. I can be convinced to drive a new car, EV or otherwise, for $15K (or even $18K), but definitely not for $30K, especially a compact car like Bolt. At $12K more than SparkEV, that's over 10 years of eating at $1/meal ($3/day), an experiment I successfully tried for months while ago, and some made documentary about such endeavor.<br />
<br />
<a href="http://www.foodstamped.com/">http://www.foodstamped.com</a><br />
<br />
If Bolt is a van, truck, or SUV that can carry stuff, it might make for a better case at $30K and so-so performance. In that regard, I wish Toyota continued to improve on Rav4EV; at 120 miles range with 0-60 in 7.2 seconds and $42K, I wish they could improve on it to bring the price down to $30K and 150 miles range; will discuss why 150 miles later.<br />
<br />
Compounding the matter is Chevy's unwillingness to participate in DCFC infrastructure. They don't have to give out free charging (<a href="http://sparkev.blogspot.com/2015/10/free-charging-sucks.html">THEY SHOULD NOT GIVE OUT FREE CHARGING</a>), but they could install them at all their dealers and charge nominal fee to recoup the cost. If they do, other EV drivers would stop by their dealer and check out Chevy cars while charging. Foot traffic at the dealer would be more than enough justification to install high power DCFC at the dealers.<br />
<br />
Alas, this is not to be, and I don't want to support a company that sells EV without adequate way to use / charge it, especially at $30K.<br />
<br />
<b>What mass market EV would I buy?</b><br />
<br />
Before this is answered, I have to answer what new gas car I'd buy. That's Hyundai Elantra. It's price is under $20K, has decent styling, close to 40 MPG, can tow 1500 lb which makes easy home depot runs for plywood using $250 harbor freight trailer.<br />
<br />
First and foremost would be pricing under $20K. At $22.5K, that's in Prius ballpark. While that's tad high for my taste, I can squeeze out bit more for better car than Elantra.<br />
<br />
Second has to be performance better than all gas cars in its price range. As shown above, Fiesta ST does in 6.7 seconds 0-60, so 6.5 seconds might be fine (Bolt may actually do this), though under 6 seconds would erase all doubt. Therefore, 0-60 must be under 6 seconds at $22.5K, preferably under 5 seconds.<br />
<br />
Third is fast charging. While home charging overnight for 12 hours is fine, DCFC must be 80% in 20 minutes or less. In this regard, it's not just EV, but Chevy must actively participate in charging infrastructure (again, DO NOT GIVE OUT FREE CHARGING!) to allow 20 minutes for 80%.<br />
<br />
Fourth, the range doesn't have to be 200 miles. Without DCFC, even 2000 miles range would not be enough. But with DCFC, it should be at least 2 hours at 65 MPH freeway with 15 minutes of charging.<br />
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65 MPH * 2 H = 130 miles<br />
<br />
But one must have some margin. Let's say 20 miles for 150 miles range, though 10 miles would be ok, too. Assuming 3.5 mi/kWh at 65 MPH including heat/AC, that works out to<br />
<br />
150 miles / 3.5 mi/kWh = 43 kWh (round up to 50 kWh)<br />
<br />
To charge 80% of 50 kWh in 15 minutes,<br />
<br />
50 * 0.8 = 40 kWh<br />
40 kWh / 0.25 H = 160 kW<br />
<br />
A 50 kWh battery charging at 160kW is rate of 3.2C. Whether current EV battery can do this is unknown. From few articles I've read, even 10C charging is possible for some chemistry. But we know SparkEV can do 48kW using 19 kWh battery, a charging rate of 2.5C (48/19). If we assume 2.5C that is currently possible with SparkEV, time to charge 80% would take<br />
<br />
50kWh * 2.5C = 125kW<br />
50kWh * 0.8 / 125kW * 60 min/hr = 19.2 minutes<br />
<br />
125kW is about what Tesla supercharger can do today. Basically, the point is that practical mass market EV charging can be done that isn't much more of a hassle than gas cars, but not with today's CCS from eVgo. Chevy must actively develop and deploy and/or help deploy such charging network.<br />
<br />
Fifth is 1500 lb towing capacity. Light towing makes the car so much more versatile. If I get another car, it will have to have towing capability. Another consideration for EV might be range extender trailer, either as extra battery or gas engine generator. Unfortunately, towing ability rules out all EV except for Tesla Model X at the moment.<br />
<br />
So how does Bolt stack up from my requirements?<br />
1. Pricing, No,<br />
2. Performance, maybe, though probably lacking.<br />
3. DCFC speed, No, especially with Chevy's lack of interest in participating.<br />
4. Range, Yes.<br />
5. Towing, No.<br />
<br />
One out of five? Not likely; I'd rather get Elantra.<br />
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<b>Mass market potential</b><br />
<br />
If above criteria are met, I suspect it'll meet the needs / expectations of most people. After all, EV that performs better than all cars in its price range AND it can charge almost like gas cars on longer trips AND all the benefits of EV, such as home charging and quiet, smooth operation is hard to pass.<br />
<br />
Some places give large subsidy for EV. US is one, and CA gives additional. Recently, Germany announced 2 billion euro to encourage EV. Big slice of that pie could go to the compelling mass market EV maker, and those who participate in charging network.<br />
<br />
<a href="http://news.yahoo.com/germany-wants-put-2-billion-euros-encouraging-electric">http://news.yahoo.com/germany-wants-put-2-billion-euros-encouraging-electric</a><br />
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<br /></div>
There's lots of money to be made for true mass market EV. Unfortunately, I don't think Bolt is it.<br />
<br />
How about SparkEV? It could very well be the mass market EV with right pricing and options and marketing. In foreign countries where the roads are narrow, small car is actually of advantage. Combined with exciting performance for price, it holds lots of appeal with proper marketing. Going through the list of criteria above,<br />
<br />
1. Sub $20K Pricing, Yes in US, probably in many other countries as well.<br />
2. Performance, Yes. Chevy need to advertise this aspect with gusto.<br />
3. DCFC speed, Yes, SparkEV is quickest charging EV in the world.<br />
4. Range, No. However, with enough DCFC and marketing, it's not as big a deal.<br />
5. Towing, No. But next gen can easily allow for this.<br />
<br />
3 out of 5 is already met today, and towing is easily resolved. In fact, range extender trailer could solve the range issue as well. All Chevy need to do is market it to take advantage of the huge potential for EV in places like Germany. It's far easier to convince people to drive kick-ass car that happen to be an EV that cost $18K ($15K in CA) than $30K that's ho-hum. I mean, Chevy already did all the engineering work for SparkEV, why abandon it? All they need is to install DCFC at all their dealers (and price it to recoup cost), and run some commercials. Who knows? Maybe people will drop by to buy Bolt and Silverado as well.sparkevhttp://www.blogger.com/profile/04362518920979349841noreply@blogger.com0tag:blogger.com,1999:blog-6875771813122616391.post-82674225812116536692015-12-07T20:13:00.001-08:002015-12-16T16:21:43.780-08:00SparkEV is quickest charging EV in the worldIf I say SparkEV is the quickest charging EV in the world, you should ask "are you insane? What kind of ludicrous claim is that? Of course Tesla is the quickest!" And you'd be correct. But it'd be also correct to claim that SparkEV is quickest charging EV in the world going by percent of battery capacity charged.<br />
<br />
<a href="http://insideevs.com/2016-30-kwh-nissan-leaf-sets-fastned-fast-charging-record/">http://insideevs.com/2016-30-kwh-nissan-leaf-sets-fastned-fast-charging-record/</a><br />
<br />
When I first read this article, I thought "what a stupid record. It doesn't matter if it's 90%. What matters is how many miles". Given that Tesla Supercharger is 90kW to 120kW (or is it? see below), there's no question Tesla would be quickest charging in terms of miles added for a given duration of time.<br />
<br />
But human psychology doesn't work that way. Humans typically try to maximize charging percent, at least to 80%, not just stop charging when there's enough miles to get home. One can see this effect at fast charge stations when you see people hanging around to squeeze out charge even when the car is charging at 2kW using 50kW charger.<br />
<br />
Most of us don't have exposure to fast charging other EV. Manufacturers do not
disclose this information. Automobile media for most parts don't even mention various types of charging, let alone benchmark charging speed. We just accept that what
we get is what we get, and assume all EV behave like the EV we drive. In
case of Leaf drivers, they would just accept that all EV charges at
<a href="http://sparkev.blogspot.com/2015/10/love-letter-to-nissan-leaf-dcfc-users.html" target="_blank">12kW at 80% using 50kW charger</a>. In my case, I assumed all EV charge at
45kW to 80%. I mean, it's called "fast charge" and it would make no
sense to charge at anything less to 80% battery capacity, the recommended capacity for batteries.<br />
<br />
Then I encountered how <a href="http://sparkev.blogspot.com/2015/05/vs-nissan-leaf-quick-charge.html" target="_blank">slowly Leaf was charging</a>. Then I found out about Tesla taking almost an hour to charge at supercharger. Then I read the article above. It became clear that SparkEV is quickest charging EV in the world. <br />
<br />
<b>SparkEV charges faster than record breaking EV</b><br />
<br />
Fast charging record the article above describe is the time it takes to reach 90%. It took 33:15 (0.554 hours) to charge 21 kWh. That works out to 37.9 kW on average. Considering that 24kWh Leaf drops to below 36kW even at 60%, the new 30kWh Leaf is significant improvement.<br />
<br />
Since the test was performed in Europe, there is no SparkEV. But there are other fast charging EV, such as Kia Soul EV and BMW i3, even EV not available in US such as Renault Zoe. If 37.9kW average power to reach 90% battery capacity is the record, that means all the other EV that are available in Europe are slower than this. As far as I'm aware, SparkEV is the only fast charge capable EV that's not available in Europe at this time.<br />
<br />
I timed a charge session from 12% to 89%. It took 20 minutes (1/3 hour) to add 13 kWh, average speed of 39kW. This is quicker than the new Leaf with 30kWh battery. Below is the screen shot of the charging session.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgzAttTK3SQcYFVGLAVzzmVjRYLuJTUMDhriDGsx486jH1JIU-O-dwOX1eQAF6MuGrJie2zyb61oG1AnW_AvJW-RudADcCPQ9UETupjzcQENImDW1pJAPn6tzM84eKbwgCvHt5IV_iRT2nc/s1600/89%2525_sparkev.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgzAttTK3SQcYFVGLAVzzmVjRYLuJTUMDhriDGsx486jH1JIU-O-dwOX1eQAF6MuGrJie2zyb61oG1AnW_AvJW-RudADcCPQ9UETupjzcQENImDW1pJAPn6tzM84eKbwgCvHt5IV_iRT2nc/s1600/89%2525_sparkev.jpg" /></a></div>
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Note that this charging power started from 12%, not 0% like in Leaf's case. If one monitors SparkEV charging at DCFC, it stays at about 45kW when it's below 80%, and tapers to 9kW at 99%. While I don't know if it's linear taper, what's important is constant charging below 80%. That means starting at lower battery state will result in even higher average power. <br />
<br />
Because SparkEV battery is only 19kWh vs new Leaf 30kWh, SparkEV would definitely win percent charged race even if the power is the same. With higher average charging power, SparkEV would be far quicker in percentage race.<br />
<br />
SparkEV is the quickest charging EV in the world!<br />
<br />
<b>Tesla Supercharging could take an hour</b><br />
<br />
By now, it should be clear that I poke my nose into other EV business as evidenced by my <a href="http://sparkev.blogspot.com/2015/10/money-mpge-for-various-ev.html" target="_blank">MPGe$ for various EV post</a> and <a href="http://sparkev.blogspot.com/2015/10/love-letter-to-nissan-leaf-dcfc-users.html" target="_blank">Love letter to Leaf post</a>. I came across an interesting forum discussion about Tesla supercharging speed. They said Tesla takes almost an hour to charge using Supercharger. They said charging time is from Edmunds article, which I googled to mean this one.<br />
<br />
<a href="http://www.edmunds.com/tesla/model-s/2013/long-term-road-test/2013-tesla-model-s-how-quickly-does-a-supercharger-charge.html">http://www.edmunds.com/tesla/model-s/2013/long-term-road-test/2013-tesla-model-s-how-quickly-does-a-supercharger-charge.html</a><br />
<br />
I didn't see what model he used, but let's assume S70 with 70kWh battery. Further, let's assume 80% of battery capacity is usable. Then the full capacity is 56kWh. The plot in the article seems to show 90kW supercharger. He started charging at range of 40 miles, which is 17% of 240 miles.<br />
<br />
56kWh * (100%-17%) = 46kWh<br />
46kWh / 90kW = 0.51 hours = 30.7 minutes<br />
<br />
If the car charged at full power, it should only take 30 minutes. Obviously, the car doesn't charge at full power all the time. But it should charge to 80% by then, right? I mean, SparkEV charges at full power (about 45kW) to 80%, Tesla has to be at least as good, right?<br />
<br />
No. When it comes to charging to X %, SparkEV is far quicker than Tesla. Tesla charges at 90kW (or 120kW) only for short time. Then it slows down very (very very) quickly. But its starting power is higher. That's the good news for Tesla; it's charging speed is quicker than SparkEV for number of miles added per unit time due to higher starting power, despite the quick taper.<br />
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<a href="http://services.edmunds-media.com/image-service/media-ed/ximm/?quality=85&image=/tesla/model-s/2013/lt/2013_tesla_model-s_det_lt_9091307_600.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://services.edmunds-media.com/image-service/media-ed/ximm/?quality=85&image=/tesla/model-s/2013/lt/2013_tesla_model-s_det_lt_9091307_600.jpg" /></a></div>
<br />
Eye-balling from the graph (red plot), it seems to show about 60kW on average, maybe 70kW to 80%. After 175 miles range (175/240 = 73%), it's slower than 50kW. After this point, SparkEV would be quicker. But "quicker" is kind of hollow; SparkEV would have about 70 miles range at this point (80%) while Tesla has 175 miles range.<br />
<br />
Fortunately for Tesla, there aren't Superchargers next to SparkEV. But if there were, it might make for small dent in Tesla pride to see tiny SparkEV charge only for 20 minutes or less and drive away while they're waiting almost an hour (or more) to get charge. Human psychology is a funny thing.<br />
<br />
SparkEV is still the quickest charging EV in the world, even quicker than Tesla!<br />
<br />
<b>Tesla Supercharging power</b><br />
<b><br /></b>
Even worse for Tesla pride might be their Supercharging power. Since I don't have Tesla, I have to go by the data from forum posts.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhuq2bJZKPirpVvlh01a1b8XrA7Cz_1iaqs3mdWLp-g5tfzFEko8Z_EvyAbmi-Fb2LKySlhZLkmNCnzDH-oEiRIFDmFXDMd3tKIf1pbDK6IeFVC2QwvGCLNtsVE8HNfnPMlX9k-CgF4Vs4b/s1600/SuperchargerPowerCurve.gif" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhuq2bJZKPirpVvlh01a1b8XrA7Cz_1iaqs3mdWLp-g5tfzFEko8Z_EvyAbmi-Fb2LKySlhZLkmNCnzDH-oEiRIFDmFXDMd3tKIf1pbDK6IeFVC2QwvGCLNtsVE8HNfnPMlX9k-CgF4Vs4b/s1600/SuperchargerPowerCurve.gif" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small; text-align: start;"><a href="http://www.teslamotorsclub.com/showthread.php/23180-Finally-120KW-Supercharging!/page21">http://www.teslamotorsclub.com/showthread.php/23180-Finally-120KW-Supercharging!/page21</a></span><span style="font-size: small; text-align: start;"><a href="http://www.teslamotorsclub.com/attachment.php?attachmentid=39704&d=1388704656">http://www.teslamotorsclub.com/attachment.php?attachmentid=39704&d=1388704656</a></span></td></tr>
</tbody></table>
<br />
It seems Tesla taper is linear. For 120kW, it starts to taper almost immediately. For 90kW, it tapers starting at about 105 miles range (out of 250 miles = 42%). 80% would be 200 miles, which shows about 45kW power. Just at this moment, SparkEV would be charging just as fast as Tesla in adding electrons to the battery (ie, absolute sense, not in %) when both cars are at 80% battery capacity.<br />
<br />
Because the slope for 120kW case is almost linear from 50 miles to 200 miles, one can estimate the best case average power by looking at the power at average of 50 miles and 200 miles (125 miles). That number is about 80kW. Since 90kW charger is slower, 80kW power is the best case scenario for Tesla to reach 80%.<br />
<br />
Technically, Tesla does charge at 120kW, but only for short time. SparkEV charges at 45kW out of 50kW charger from 0% all the way to 80% battery capacity. In terms of charging power with respect to advertised charger power, SparkEV is 90% of peak power while Tesla is only 67%.<br />
<br />
SparkEV is still the quickest charging EV in the world, even at utilizing fast charger capacity!<br />
<br />
<b>Slow Tesla supercharging on same circuit</b><br />
<br />
Researching into Tesla super charging, I came across supercharger installations. Multiple Teslas can charge from superchargers on same circuit, but reduce power to each vehicle. While it's not clear how often this happens, and how the power is reduced, what seem to happen is that charging power could be significantly lower.<br />
<br />
I'm just guessing here. Ideally/worst case, two EV on one circuit would reduce the charging power by half (45kW from 90kW charger), four EV on one circuit reduce the power by four (22.5kW from 90kW charger). But Tesla has very steep charge taper. Unless both Teslas with similar state of charge are plugged in at the same time, the balance of power may not be evenly split. Well, it wouldn't be if Tesla designed it like I would! But people who use supercharger would typically have low state of charge, so evenly split scenario might be more common. I mean, that's why they're there, right?<br />
<br />
It's not clear if more than two sharing is allowed with same circuit superchargers. But if two Teslas with low state of charge are charging together using 90kW supercharger, the power delivered would be slightly less than SparkEV. If one considers some losses, SparkEV might be even quicker than Tesla to 80% (or even more?), not just in percentage race, but actual delivered electrons.<br />
<br />
One might argue that current crop of CCS DCFC (made by ABB) does not allow multiple vehicle charging simultaneously, so the time taken by multiple vehicles should also consider waiting time for SparkEV. In fact, since one's locked out of charging while another is in progress, that's worse than Tesla charging where they can plug in and walk away. That is actually a very valid point. However, it's my blog, I'll tweak the parameter to favor SparkEV this time, unlike <a href="http://sparkev.blogspot.com/2015/09/ev-ranking.html" target="_blank">ev-ranking</a> blog post where I tweaked the parameter to favor Tesla.<br />
<br />
SparkEV could be even quicker than some shared circuit Tesla supercharging, not only in percentage race, but actual electrons delivered! This would make SparkEV the quickest charging EV in the world from all points of view.<br />
<br />
<b>Conclusion</b><br />
<br />
For a cheap "<a href="http://sparkev.blogspot.com/2015/11/sparkev-you-are-not-compliance-car.html" target="_blank">compliance car</a>" as some continue to insist, SparkEV is quickest charging EV in the world. For some situations, SparkEV is even quicker than the mighty Tesla supercharger with regard to amount of energy gained, not just percentage. Maybe one day, all EV will charge as quickly as SparkEV, the reigning king of fast charging.<br />
<br />
As far as I know, no automobile publication or blog or other sources
discuss and rank fast charging speed. This might be the historical
first! Going forward, I hope publications include this benchmark. 0-60 time is so 20th century, battery range is so 1999. Benchmarks should include DCFC speed. Welcome to 21st century!<br />
<br />
<b>Edit 2015-12-15</b><br />
<br />
One can guesstimate "instant" charging power by timing how long it takes to charge 0.01kWh (or more), because ABB charger does not give instantaneous power. SparkEV displays instantaneous charging power when it's "on" while charging. I did this long ago, and it showed about 45kW below 80%; it was fluctuating between 42kW and 48kW.<br />
<br />
I was monitoring it again today, and it was fluctuating between 47kW and 48kW! I think this has more to do with charger and ambient temperature, although it had firmware update since the last time I was monitoring it. The screen shot was made when it had close to 80% as you can see from the "green goo" bar graph on the left that represents battery capacity.<br />
<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIdTY7O7r2FRfa2SEThuf8Xku2zuv8aSScJATlqHn05PSTmaPe90DgMB72DDKxGSNPm6aU_Id29Mb1kfMhWzrNIpzV26Gr1grSiGySHvd9xS32slQ-NfnZ0UxZ0reCFrkLFW-_NdTCdICh/s1600/abb_48kw.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIdTY7O7r2FRfa2SEThuf8Xku2zuv8aSScJATlqHn05PSTmaPe90DgMB72DDKxGSNPm6aU_Id29Mb1kfMhWzrNIpzV26Gr1grSiGySHvd9xS32slQ-NfnZ0UxZ0reCFrkLFW-_NdTCdICh/s1600/abb_48kw.jpg" /></a></div>
<br />
Unfortunately, I got distracted and went way over 80% (Puppy is misspelled word for Poop Pee), and also forgot to take photos from ABB charger after charging was done, so I don't know what the average power was. But it shows SparkEV is capable of using 96% of charger power to 80% (48kW out of 50kW charger). I have to wonder how fast it would charge if there are chargers with more power.<br />
<br />
And what do you know? Insideevs had an article on just this topic. It's about 30kWh Leaf setting new fast charging record using different charger in Europe.<br />
<br />
<a href="http://insideevs.com/2016-30-kwh-nissan-leaf-fast-charging-record-21-03-kwh-26-5-minutes/">http://insideevs.com/2016-30-kwh-nissan-leaf-fast-charging-record-21-03-kwh-26-5-minutes/</a><br />
<br />
From the comments, it seems the new charger is 120kW unit capable of two simultaneous DCFC. It's capable of 60kW as base model, higher power than 50kW ABB unit that's in CA today.<br />
<br />
<a href="http://www.evtec.ch/en/products/espressoandcharge/">http://www.evtec.ch/en/products/espressoandcharge/</a><br />
<br />
Leaf charged 21.04kWh in 0.4425 hours which is 47.5kW on average. Oddly, it showed that is 80% battery whereas previous record (37.9kW described above) was also 21.04kW but to 90%. If we assume the race to 80%, SparkEV would be close to or faster than new Leaf with bigger battery using the higher power charger, even when SparkEV is using the lower powered unit. I have to wonder how fast SparkEV would charge using the higher power charger.<br />
<br />
Who wouldn't make such capable car that's probably quickest in the world available everywhere and talk about canceling it? Why, the dunces of GM, of course!<br />
<br />
<b>Edit 2015-12-16</b><br />
<br />
% charged is important metric, because this is the amount of time one would spend at the charger. People don't charge to X miles when they've only charged to 30% battery, just enough to get home. People generally stick around to 80% or more, regardless of the miles. For the real-world charging scenarios, SparkEV wins this contest by far against all EV in the world.<br />
<br />
Another important metric is miles added for given time (charged miles per hour), not the kilowatt that I focused on previously. For more miles added, one can take longer trips even if multiple DCFC sessions are required. As an extreme example, if SparkEV can add 300 miles in 20 minutes, it would be even quicker than Tesla in driving 500 miles; Tesla would need 2 DCFC seesions at 1 hour each (2 hours) whereas SparkEV would need 7 DCFC sessions (72 miles each), each lasting only 5 minutes (35 minutes total).<br />
<br />
There are two ways to achieve higher miles added per time. One is to have higher average power in charging (aka, brute force). Another is to have more efficient vehicle (aka, elegant efficiency). Because SparkEV is more efficient than either the Leaf or Tesla, even lower charging power would benefit SparkEV in terms of adding miles per time. Table below shows the calculations. Before you jump on "your table is ludicrous for making SparkEV faster than Tesla", read the explanations below.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjO_g_xer8dg3vFKERljbwoKvr06xg9huIR4vRlgNThQlXaU_hDTvFBKAZ8JGusNqTgA3NJG9JpUICZY6_UtMw73ggSzhrutvFg6qzSnuuVyF6gah6Obv5Xmzv9hjf9gt3KEH6JGAn_fH6Q/s1600/charging_mile_per_hour.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjO_g_xer8dg3vFKERljbwoKvr06xg9huIR4vRlgNThQlXaU_hDTvFBKAZ8JGusNqTgA3NJG9JpUICZY6_UtMw73ggSzhrutvFg6qzSnuuVyF6gah6Obv5Xmzv9hjf9gt3KEH6JGAn_fH6Q/s1600/charging_mile_per_hour.gif" /></a></div>
<br />
<br />
All figures are based on EPA MPGe except for the top entry which is based on mi/kWh that I measured for SparkEV for driving at constant 55 MPH and 93% DCFC efficiency (5 mi/kWh * 0.93 = 4.65 mi/kWh). I also use best case charging power I've seen using 50kW charger, which is 48kW; since we don't have higher power chargers in CA, this is probably low estimate for what SparkEV can do in terms of charging power. It's certainly within the realm of possibility even with 50kW charger.<br />
<br />
For the rest (not the first row), I use EPA MPGe figures. For SparkEV, I explore the case of 48kW and typical case of 45kW, both figures actually observed with 50kW charger.<br />
<br />
Since I don't have Tesla, I have to eye-ball the average charging power from the graphs above. I use 80kW average for 120kW supercharger, 70kW for high estimate of 90kW supercharger, and 60kW for low estimate of 90kW supercharger.<br />
<br />
For Leaf, I use charging power figures from Insideevs.com articles. Although 37.9kW was supposed to be to 90% using ABB charger, same energy in kWh was added as 80% case with evtec charger.<br />
<br />
While it's not apples to apples, SparkEV comes out ahead of even Tesla in miles added per unit time in low estimate (60kW) for Tesla supercharger. This is not surprising since SparkEV would add about 70 miles in 20 minutes, about 200 miles in one hour. This is about the time Tesla driver spent at supercharger in Edmunds article mentioned above.<br />
<br />
So even using almost apples to apples comparison, SparkEV does very well in miles added per time against Tesla, even better than low estimate for Tesla . But we have't seen the best of SparkEV, yet, due to lack of higher power chargers. It's certainly in Tesla's league at the moment, and with higher power charger, it could exceed 90kW Tesla supercharger in miles added per time.<br />
<br />
Using real world efficiency of SparkEV compared to EPA MPGe, SparkEV is quickest charging EV in the world in every sense, even quicker than Tesla. Not apples to apples, I know, but it's not likely that I'll have Tesla any time soon for apples to apples comparison.sparkevhttp://www.blogger.com/profile/04362518920979349841noreply@blogger.com10tag:blogger.com,1999:blog-6875771813122616391.post-12352793436604634232015-11-15T08:46:00.000-08:002015-11-21T11:59:07.493-08:00SparkEV, you are NOT a compliance carI didn't want to discuss this, because it was so obvious, but it seems some (many?) have mistaken notion that SparkEV is a compliance car. This post is to show some evidence that isn't the case.<br />
<br />
<b>Compliance 101</b><br />
<br />
For those not aware, few states in US mandate few percent of total car sales must be zero emission vehicles (ZEV). They also create a market for it such that car companies that sell more ZEV than required can sell the excess sales figure as "ZEV credit". Some gasbags claim that Tesla is making out like bandit for selling ZEV credit than actually selling cars; if you can't see the flawed logic in this argument, please, read it over again. (hint: you must sell ZEV to get ZEV credit!)<br />
<br />
There used to be one ZEV mandated state: CA. Then OR joined. Now supposedly there are several ZEV states operating as co-op where credit sold in those states can be applied to over all pool.<br />
<br />
<b>Definition of compliance car</b><br />
<br />
As such, the definition of compliance car is simple. It's cars only sold in compliance states (CA and OR for now) only for the purpose of getting ZEV credit for them to sell more gas cars. The reason they don't sell outside of compliance states is due to cost. Even though the car maker can buy ZEV credit from their competitors (eg. Tesla), it does nothing for them while boosting the competitor's bottom line. Even if they're losing some money (or lots of money) by selling ZEV in compliance states, it'll at least bring the people into their dealers and keep the money out of their competitors' bottom line.<br />
<br />
One famous compliance car is Fiat500e. Sergio (Fiat CEO) famously said that he hopes people don't buy the 500e, because the company loses $14,000 for every car sold. Whether this is reverse psychology is debatable. But the little Fiat is a down to a tee (cee?) example of a compliance car. Supposedly, the CEO had such disdain for BEV that much of the drive train of 500e were not made by Fiat, but contracted out to Bosche. As such, there's no hope of making money by selling another company's car, especially if that car must use biggest (and most expensive) available battery among mid level EV at the time.<br />
<br />
<b>You dirty compliance car!</b><br />
<br />
Some consider
compliance cars as a dirty word. They see them as taking away from "true"
EV and helping the evil gas car maker that'll make even more CO2. It's
like they have some religious aura about disliking compliance car outside
of logic and reason.<br />
<br />
The simple fact is, compliance cars are just as much EV that
doesn't use imported oil. If the compliance car performs better and cost
less than "true" EV, by all means, I whole heartedly recommend
compliance cars. If they didn't offer this better and low cost EV, would consumers buy more expensive and crappier "true" EV or would they simply buy gas cars? Most would probably buy gas cars, making the situation (imported oil and CO2) far worse.<br />
<br />
Compliance cars would be losing money for the car maker. If they made money, they'd have wider sales (see below why not always the case). If the evil car maker is only selling compliance BEV to be able to sell more gas cars, and their BEV is good / cheap, it's all the more reason to buy them. Buying their compliance EV and hurting them financially is a good thing if you happen to dislike the car maker.<br />
<br />
Here's an example. Fiat 500e is pretty much the definition of compliance car. But if it came with DC fast charging and cost comparable to SparkEV ($26K, $7K less than current 500e price), it would be a great tiny car: 0-60 in bit over 8 seconds, almost 2 seconds quicker than Leaf, and it comes with 6.6kW L2 instead of SparkEV's 3.3kW. Personally, I like the taller head room of SparkEV, but for smaller people who like "cute" cars, it would've been the best EV. It'd even be a great choice for people who live in areas without much DCFC now (will be coming), but many L2. Compliance or not, such car would be a great buy.<br />
<br />
<b>SparkEV compliance test</b><br />
<br />
SparkEV is sold in limited number of state, CA and OR in the beginning, also in MD as of third quarter of 2015. Hmm. Smells like compliance car.<br />
<br />
Lesser known is that SparkEV was also sold in Canada to fleet customers from the beginning. Starting in 2016, SparkEV will be sold retail as well in Canada.<br />
<br />
<a href="http://media.gm.ca/media/ca/en/gm/news.detail.html/content/Pages/news/ca/en/2015/Apr/0409_Spark.html" rel="nofollow">http://media.gm.ca/media/ca/en/gm/news.detail.html/content/Pages/news/ca/en/2015/Apr/0409_Spark.html</a><br />
<br />
SparkEV also has been selling in South Korea since the beginning.<br />
<br />
<a href="http://insideevs.com/sales-of-chevy-spark-ev-now-officially-underway-in-south-korea/" rel="nofollow">http://insideevs.com/sales-of-chevy-spark-ev-now-officially-underway-in-south-korea/</a> <br />
<br />
SparkEV is also sold in Mexico.<br />
<br />
<a href="http://www.chevrolet.com.mx/spark-ev-vehiculo-electrico.html" rel="nofollow">http://www.chevrolet.com.mx/spark-ev-vehiculo-electrico.html</a><br />
<br />
Just from the fact that SparkEV is sold in places outside of compliance states of US means SparkEV is NOT a compliance car.<br />
<br />
<b>SparkEV pricing</b><br />
<br />
Mexico is an interesting link. The price in the web site in Mexican Peso converted to US dollar result in $24K while it's sold as $26K in US. If it's only for compliance to meet ZEV credit in certain US states, why would Chevy sell SparkEV in Mexico for even lower price than US and lose even more money? Are they insane? Or more insane than usual? hint: Iron Duke Camaro! <br />
<br />
Most likely, Chevy probably isn't losing money by selling SparkEV, but making money. Otherwise, why offer for sale in places that do not mandate it? Based on Mexico price, they're probably making $2K to $3K per car in US. This could be more than 10% profit, a profit margin that even Carlos Ghosn, the legendary CEO of Nissan, would be proud of.<br />
<br />
By the way, Carlos will be a historic figure, and all those who's shaken his hand or have some memorabilia from/about him is well advised to keep them safe; they will become valuable to your grand kids. No, I'm not suggesting that you cut off the hand that shook Carlos' hand, but don't wash it. Ever!<br />
<br />
<a href="https://en.wikipedia.org/wiki/Carlos_Ghosn">https://en.wikipedia.org/wiki/Carlos_Ghosn</a><br />
<br />
Even without knowing Mexico pricing, let's deduce how much SparkEV would cost. SparkEV is basically Spark gas version converted to EV. Much of the car's body and chassis is the same, adding only minor cost. Electric motor is made by GM, a derivative of Chevy Volt motor. Then the gas engine swapped with electric motor is only minor cost difference, if any. Biggest addition is the battery. Assuming $300/kWh, 19kWh battery would cost $5700; let's round up to $6000.<br />
<br />
Spark gas 1LT costs $15,000. Assuming 10% extra for swapping gas engine for electric motor and adding $6000 for battery,<br />
<br />
$15,000 * 1.1 + $6000 = $22,500<br />
<br />
Well, well, what do you know? It's $1500 less than MSRP in Mexico, and $3500 less than MSRP in US. Those are some healthy profits for Chevy!<br />
<br />
<b>Why not sell SparkEV throughout US and the world?</b><br />
<br />
From above, it should be clear that Chevy is probably making<b> </b>money by selling SparkEV. Then the question becomes, why not sell it everywhere? Why only in few markets (some outside compliance states)? Indeed, Chevy had announced much wider sales in the beginning, only to cancel them later. They wouldn't have done that if it was compliance only car. This involves guessing, so I'll present a few.<br />
<br />
One reason could be the US federal tax credit for EV. Each car maker is allowed 200,000 EV sold before the tax credit is sunset. Chevy has already used up about 100,000 with the Volt and Cadillac ELR. If they use up all the tax credits before their upcoming Chevy Bolt is released, the fear is $7500 higher price than the competition (Tesla Model 3, new Nissan) will doom the Bolt sales.<br />
<br />
SparkEV sold about 950 cars in Apr. 2015 in only 2 states, probably much of it in second half the month when they announced price reduction. Subsequently, they have been constantly sold out in much of the dealers, so the sales figure is less and hard to gauge the demand. But if 950 car in 1/2 month in 2 states (about 20% of US population), nationwide roll out would result in 950 * 2 * 5 * 12 mo = 114,000 cars per year. That'll pretty much wipe out the entire tax credit even before first Bolt rolls out of the assembly line. Even considering 1/5 of that figure (about 35,000 cars sold for 1.5 years before Bolt), that'll eat into tax credit in significant numbers.<br />
<br />
Another reason could be that Chevy is being cautious with all battery EV by testing the waters with SparkEV. In case it doesn't hold in limited markets, they're not likely to lose out much. Indeed, releasing in hot climate (Mexico) and cold climate (Canada) is just such test, and it doesn't cost Chevy a dime while they gather valuable data on their BEV performance in the real world. In fact, they probably make some good profit from conducting the test. And SparkEV drivers benefit from being able to drive what is the best BEV for the money available in the market today. Everyone benefits without too much risk for Chevy.<br />
<br />
Then there's the gloomy reason: Chevy isn't serious about BEV, and SparkEV is a ploy to keep green naggers off their back. In Mexico with the awful air quality in some cities, selling SparkEV would be a ploy to get people to Chevy showrooms. In Canada, well, there are some crazy Canadians who dare drive EV there, too (hi Andrew!). MD is where SparkEV motor is made, so that'll be a good PR for them. Basically, Chevy's main reason for SparkEV is meeting compliance requirements, and doing very little else to keep naggers at bay. But even so, having the best EV in the world available at some places is better than not having it at all.<br />
<br />
It could be combination of reasons, different reasons, no reason at all, who knows? But above try to make some semblance of reasons why Chevy is doing what it's doing with SparkEV limited release. Sometimes, human mind just keeps asking, "why? why? why?"<br />
<br />
But one thing is clear. Mr. Maury Povich, take it away.<br />
<br />
<b>SparkEV, you are NOT a compliance car.</b><br />
<br />
<b>Edit Nov. 19, 2015</b><br />
<br />
If SparkEV is a compliance car, how many cars would Chevy need to sell to qualify? We don't know exactly, but we can get some clues from other compliance car sales. According to insideeves.com, Oct 2015 sales report, Fiat 500e sold 5539 cars while SparkEV only sold 2311 cars.<br />
<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: center; margin-right: 1em; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://insideevs.com/wp-content/uploads/2015/11/2015-sales-chart-october-vfinal3-750x636.png" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" src="http://insideevs.com/wp-content/uploads/2015/11/2015-sales-chart-october-vfinal3-750x636.png" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><a href="http://insideevs.com/october-2015-plug-electric-vehicle-sales-report-card/">http://insideevs.com/october-2015-plug-electric-vehicle-sales-report-card/</a></td></tr>
</tbody></table>
<br />
SparkEV is selling for about $7000 cheaper, leasing for $1600 cheaper, it's quicker, it has DCFC. One would think that SparkEV has some other major problems, and thousands of them are sitting at dealer lots. But that isn't the case. SparkEV is constantly sold out. In fact, I'm surprised that they managed to sell even 177 cars in Oct. 2015. Where are they selling? It's not in SoCal as it's been sold out within 250 miles of here for since June of 2015.<br />
<br />
Fiat 500e is selling more than twice as many as SparkEV, a car that supposedly loses $14,000 for each sold and their CEO famously quoted as saying they won't sell a single car more than necessary. That suggests Chevy should make lots more SparkEV to meet the demand to meet compliance; having it sold out makes no sense.<br />
<br />
Then why not sell more SparkEV? Demand is certainly there judging from sold out dealers. There is no way to know for certain unless you're the decision maker at Chevy. But the clues seem to indicate that they are trying to save federal tax credit for the upcoming Bolt. It's the only logical explanation for selling fewer SparkEV than Fiat 500e.<br />
<br />
But then, GM hasn't always been logical, such as when they scrapped the EV1 program that included hybrid models after spending billions on research. Meanwhile, Toyota went on to become the world leader in auto sales, probably thanks to the positive perception brought by the Prius, which was probably crappier than EV1 hybrid.<br />
<br />
GM has great engineering talent as shown by EV1 (many Tesla engineers previously worked on EV1), and now the SparkEV. Let's hope that GM executives have caught up to their engineering talent and do the right thing this time and not let the almost sure thing slip through their grasp again.sparkevhttp://www.blogger.com/profile/04362518920979349841noreply@blogger.com2tag:blogger.com,1999:blog-6875771813122616391.post-87294699869329163122015-11-10T17:20:00.000-08:002015-11-10T17:21:25.716-08:00SparkEV destinyI don't know if this is true, but this post was found in Tesla motors club forum by a user named "Red". If true, Spark was destined to be an EV, and EV is merely fulfilling its destiny. I sincerely hope that it can live on as EV for a long, long time. May you live long and prosper, SparkEV.<br />
<br />
<a href="http://www.teslamotorsclub.com/showthread.php/6557-Chevrolet-Spark-EV?p=451641&viewfull=1#post451641">http://www.teslamotorsclub.com/showthread.php/6557-Chevrolet-Spark-EV?p=451641&viewfull=1#post451641</a><br />
<br />
"GM wrong about itself<br />
<br />
Actually GM is wrong when admitting the Spark was not designed as an EV.<br />
<br />
It actually was, just not thoroughly, because it was one of the earliest ones. Spark is basically a reworked Daewoo Matiz, which was originally designed by Italdesign for a partnership between FIAT and the EV drive train pioneer Miro Zoric, who created the first inverters for AC motors, yes, even those in the Tesla. First for industrial use and then for automotive use. He also made first drive trains for GM's EV1, for instance... AC motors were a non existing option for cars before that. They were not controllable. In a way, due to that breakthrough, today batteries are the narrow throat, since AC drive trains are usable and efficient now.<br />
<br />
Anyway, what was later known as Matiz, was originally intended to be FIAT's first electric car. A small but zippy city commuter. Due to administrative issues, Gianni Agnelli's desire to have each FIAT model also have an electric version by 2000, was put aside and Daewoo bought the Matiz design and GM later bought Daewoo and renamed Matiz into the Spark. So in terms of legacy, the Spark did start out as a would be EV, but not in the way most would think.<br />
<br />
And it was originally supposed to have an AC motor and lead acid batteries, since Mr. Zoric only made rechargeable zinc air batteries (first one in the world) slightly later, in 1997. Because they would take up more space than lad acid, the little car would have lead acid batteries initially and zinc airs were used in buses and trucks. Some trivia "<br />
<br />
Thanks, Red. Haven't seen recent posts from you in a while in Forum. I hope you're doing well.sparkevhttp://www.blogger.com/profile/04362518920979349841noreply@blogger.com0tag:blogger.com,1999:blog-6875771813122616391.post-13207796523869943412015-11-03T13:50:00.001-08:002016-10-20T13:29:03.933-07:00Can stock Corvette beat Tesla P90DL in 0-60MPH?With the recent news about Tesla's announcement that P85D/L usable power is not simple sum of each motor power, it got me curious why much higher power gas cars that weigh less would be slower in 0-60 mph than P85D (or P90DL). The usual argument goes like this.<br />
<br />
1. EV has torque available from 0 RPM. But my question is why doesn't the gas car have peak torque available at 0 RPM?<br />
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2. EV (P85D/L) does not have to shift gear. But my question is why does gas car have to shift gear?<br />
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I thought these are obvious question, but after having some "debate" in forums, it seems people aren't versed in basic Physics and manual transmission to be able to understand what I'm saying. Therefore, if you haven't had basic Physics or you don't understand how manual transmission and clutch works, you should understand them before continuing with this post. It also helps if you know how to pull a wheelie on a motorcycle.<br />
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I'm going to be using Corvette Z06 as an example gas car for this post, but it could be any car with comparable performance. While Dodge Hellcat has more power, I can't stand Sergio (their CEO) for making stupid comments about EV and not improving on Fiat500e with DCFC or making better EV, so I won't be using it in this post. Sorry Hellcat; I like you, but not your CEO.<br />
<br />
<b>Making an EV out of gas car</b><br />
<br />
Gas cars produce peak torque at specific engine RPM, and fully open throttle. Outside of these conditions, torque is far less. One only has to look at power profile curve to see this. Below is 2015 Corvette Z06 power profile.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><span style="margin-left: auto; margin-right: auto;"><a href="https://www.blogger.com/goog_1462834624"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhnwv4uCsAR2apwKkod6ya6GYGX8etFYjbkvvnBj4LJY9XxuxzgmYNzS6hw_rcDeg0kWIQPPh-u43eBqB9Gh41uMaBZt3Y0Md0Hvdcpx0iiyJIte7Mk_6il_I7Q49KYyjkxWOUb6mbZclnT/s1600/2015-chevrolet-corvette-z06-lt4-torque-curve.gif" /></a></span></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><a href="http://image.motortrend.com/f/wot/1406_2015_chevrolet_corvette_z06_makes_650_horsepower_and_650_lb_ft_of_torque/72092521/2015-chevrolet-corvette-z06-lt4-torque-curve.jpg">http://image.motortrend.com/f/wot/1406_2015_chevrolet_corvette_z06_makes_650_horsepower_and_650_lb_ft_of_torque/72092521/2015-chevrolet-corvette-z06-lt4-torque-curve.jpg</a></td></tr>
</tbody></table>
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<br />
If there's a way to keep the engine running at 3600 RPM with FULLY open throttle at 0 MPH, full torque 650 ft-lb from the engine would be available from the very start. Is there a way? Of course there is; simply FULLY open the throttle with clutch disengaged, and the engine will happily rev far past 3600 RPM. Hopefully, it has rev limiter so that the engine doesn't fall apart!<br />
<br />
So if there's a way to make the engine speed to peak torque RPM from 0 MPH, how do we control the engine speed with FULLY open throttle so that it stays at peak torque of 3600 RPM instead of going to rev limiter? Simple: clutch slip. If the clutch is allowed to engage partially and allowed to slip, the torque at either ends of the clutch shaft must be the same to keep the engine RPM constant. Essentially, the torque at 0 MPH now becomes peak torque of the engine, not the torque at idle.<br />
<br />
Some suggested that clutch slip results in loss of torque; if the engine RPM is kept constant, there is no loss of torque. Some suggested power is lost on clutch; yes, but power to wheels is related to wheel RPM, and clutch friction loss does not enter into the picture. Even for Tesla, instantaneous power at 0 MPH would be 0 horsepower (or watts or whatever unit of power you want to call it). This is why I asked for basic Physics as prerequisite for reading this post.<br />
<br />
Doing this requires careful control of the clutch. Some have suggested that such fine control over clutch slip is very difficult or not possible. Or is it?<br />
<br />
<b>Enter the Motorcycle</b><br />
<br />
Let me back up here, and give an example of this type of activity being done on daily basis by rank amateurs: motorcycle wheelie. Most motorcycles don't have enough power at low RPM to be able to pull a wheelie. The problem is worse for high peak power sports motorcycles as they have very little power in low RPM. Knowing that even 90cc motorcycles can pull a wheelie that sometimes require 2G of acceleration, something is being done to allow that from even tiny engines.<br />
<br />
Don't try this at home, kids. The way they pull a wheelie is to rev the engine at sufficiently high RPM, and let the clutch slip to accelerate much quicker than their low RPM engine torque would allow. On high power sports bikes on the freeway speeds, they "blip" the clutch (don't do it!). Once the front wheel rises and the center of mass has shifted sufficiently, less acceleration is needed, and the clutch is allowed to fully engage. At that point, it's a matter of balancing, and very little power is needed.<br />
<br />
It's easier to wheelie with high power sports bikes since they have higher center of mass. Doing this on 90cc motorcycle requires careful dance on the clutch lever for much longer time to allow sufficient wheel rise to take place. Indeed, I tried this many times long ago when I had one cylinder, 250cc 300 lb motorcycle that got 15HP peak power and 80 MPG (only in private parking lots with owner's permission; please don't arrest me!). Even something as wimpy as 20 lb/HP vehicle can pull 2G of acceleration, surely something with 650HP engine at 5.4 lb/HP should be able to pull 1.1G for 2.5 seconds, right?<br />
<br />
<b>Gears, shemears</b><br />
<br />
Another problem often cited by EV folks is that gas car must change gears. That's not true. If the gas car keeps it in one gear that'll allow it to run at 60 MPH, there is no need to change gears. Corvette would run under 6000RPM at 60 MPH even in first gear. But clutch slip would be the mechanism to match engine's single RPM (peak torque RPM) to variable wheel RPM, not gear change. Looking at Corvette Z06 gearing, it seems 60 MPH would result in 4161 RPM in second gear and 3128 RPM in third gear. The gearing data is from Chevy web site.<br />
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http://media.chevrolet.com/media/us/en/chevrolet/vehicles/corvette-z06/2015.tab1.html<br />
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<br /></div>
<div>
The RPM at 60 MPH calculation is from</div>
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<br /></div>
<div>
http://xse.com/leres/bin/gearratio?title=WHT+Z06+with+MM6+manual+and+GU6+3.42+gears&rpm=7000&mph=60&gear1=2.29&gear2=1.61&gear3=1.21&gear4=1.00&gear5=0.82&gear6=0.68&reverse=2.90&axle=3.42&tire=diameter&diameter=26.69&circumference=83.85&revs=756&section=&profile=&wheel=</div>
<div>
<br /></div>
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Let's use third gear and clutch slip to allow peak torque to take place. Second gear means more torque to the wheels, but we have to remember to fully engage the clutch and allow the engine to rev beyond 3600 RPM within the run. For driver sanity, using the third gear would let him (me!) not worry about RPM other than 3600.</div>
<div>
<br /></div>
<b>Traction</b><br />
<br />
There is one potential problem with this approach, and that is traction. Given that Corvette is RWD while P90DL is AWD with intelligent traction control, putting down all that power may simply spin the rear wheels. Again with basic Physics, static coefficient of friction is far higher than kinetic coefficient of friction.<br />
<br />
For example, if Corvette did the run with third gear (1.21 * 3.42 final drive = 4.14), and 26.7 inch diameter wheel, driving force at the contact patch of the tires would be<br />
<br />
650 ft-lb * 4.14 / (26.7 in / 12in/ft / 2) = 2418 lb (each rear tire would be 1209 lb)<br />
<br />
Corvette weighs 3524 lb. Knowing that Corvette can pull more than 1G, the minimum power needed to break traction would be 3524 lb. Third gear is not enough to break traction, but that's also not enough to push it quicker than P90DL mode. 2418 lb to push 3524 lb car would result in acceleration of only 0.69G, about that of P85D sports mode. Using peak torque RPM will not allow the Corvette to out accelerate P90DL. Scotty, we need more power!<br />
<br />
<b>May the force be with Vette</b><br />
<br />
What we need is at least 3524 lb of driving force. Using first gear, 60 MPH would be 5919 RPM; let's say it's 6000 RPM. At this RPM, there would be about <strike>600</strike> 550 ft-lb of torque read from the graph. With gearing 2.29 * 3.42 final drive = 7.83,<br />
<br />
550 ft-lb * 7.83 / (26.7 in / 12in/ft / 2) = 3871 lb<br />
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3871 / 3524 = 1.1G of acceleration! We are there! If we keep the engine running at 6000 RPM with fully open throttle and modulate the clutch to keep it there while accelerating, Corvette would pull 1.1G from stand-still all the way to 60 MPH. It's 10% quicker than falling.<br />
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This assumes traction holds. This is not "popping the clutch" where the torque at the wheel could exceed the traction limit via flywheel momentum change. This is controlled modulation of the clutch, and the torque at the wheels is not allowed to go beyond accelerating at 1.1G. Whether the stock tire would allow this is unknown, but with rear wheel contact patch pushed down from body torque due to acceleration, I'm pretty sure it will hold, especially considering that skid pad (maximum lateral acceleration) is rated at 1.2G.<br />
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At 60 MPH, it is 88 ft/sec. 1.1G is 35.42 ft/sec2. This would result in 0-60 MPH time of (drum roll...)<br />
<br />
2.48 seconds!<br />
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Corvette just beat Tesla P90DL. HOLY SHEEEEEEE! Oh well, it's only in theory in some obscure blog about a "compliance" EV.<br />
<br />
<b>Help me, Obi-won</b><br />
<br />
If this was actually carried out, the price we pay to win may make the victory hollow.<br />
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First is the question of traction. We have to get the RPM just at 6000, and no less (more would be ok). If the RPM dips any less, there will be more torque, and the rear tires could make plenty of smoke. The advantage of using the peak torque gearing (third gear) was that no matter which way you go, it's not likely to break traction due to less torque, but that wouldn't be quick enough. One can argue that using higher RPM where less torque is available while keeping the car at 1.0G (2.73sec 0-60 mph) may make it more manageable. Maybe, maybe not. That will take experiments to find out.<br />
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And those experiments will cost you dearly. For each run, you're essentially dumping lots of power into the clutch, with standstill dumping almost 600 HP to poor clutch. Assuming that clutch response with all that power (aka, heat) is manageable, it will surely reduce its life. It's not clear how long it'll last. One run? Two runs? I suppose Chevy engineers would know, but would you burn up the clutch on each 0-60 MPH run with ~$100K car? Each clutch job may cost more than 3.25 years of SparkEV lease! It's not likely that anyone would do such a thing, and such run would not be valid, would it?<br />
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<b>Leia, I am your experiment</b><br />
<br />
Each time a manual transmission car starts from stand-still, it slips clutch. Each gear change involves minute amount of clutch slip. Basically, clutch slip is normal operating mode of manual transmission cars. If that's the case, extreme clutch slip is not out of the operating mode, although it's not something you see everyday (other than motorcycle wheelies; no officer, I did not pull a wheelie!). Without quantifying what amount of clutch slip is legitimate, slipping the clutch all the way to 60MPH would be valid.<br />
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Question is, is anyone nutty enough to do it? Well, there are plenty of people nutty enough to drive a 4 door sedan with electric drive train that can take them from 0-60MPH in 2.8 seconds. Worse, there are those who dare drive a "compliance EV" and damn proud of it! I don't see why there wouldn't be some who would burn up their Corvette clutch for bragging rights.<br />
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Now where are my girlfriends, one with Chemical engineering degree who own bunch of Corvettes and another with Electrical engineering degree who own bunch of Tesla P90DL? Are you reading this? ;-)<br />
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<b>Edit Nov 4, 2015</b><br />
<br />
After sleeping over this (don't we all dream about cars and/or motorcycles in our sleep?), I think sanity check is in order. We know Corvette's 0-60mph is 2.95 sec. If we assume that clutch is fully engaged as soon as possible off the line and first gear is maintained, we can calculate how long it'll take for 0-60. Then we can compare to actual run time to see how close the calculations are.<br />
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Unfortunately, the torque data isn't available, only the graph. We can "eye-ball" some values from the graph and make rough calculations. How far off can we be? As far off as the eye ball and my biases allow!<br />
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The torque number we are after is average torque from lowest to 6000 RPM. It's pretty hard to tell, especially only 2 numbers are available: 650 ft-lb at 3600 RPM and 533 ft-lb at 6400 RPM converted from peak horsepower number. I don't know, lets just guess 450 ft-lb. While it could be higher, torque above 600 ft-lb would result in greater than 1.2G skid pad limit in first gear and resulting tire spin, so one would have to try to stay below it. Assuming 550 ft-lb is used as peak torque, using 450 ft-lb as average would not be unreasonable.<br />
<br />
450 ft-lb * 7.83 / (26.7 in / 12in/ft / 2) = 3167 lb<br />
3167 / 3524 = 0.9G<br />
88 ft/sec / (0.9G * 32.2 ft/sec2) = 3.03 seconds<br />
<br />
We are in the ballpark to actual experiment data with our calculations, so I feel more confident that clutch slip method could yield quicker 0-60 mph than P90DL.<br />
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<b>Edit Nov. 5, 2015</b><br />
<br />
I just can't seem to leave it alone, can I. I've been accused of being ignorant of Physics and not knowing how manual transmission and clutch works. Of course, both are wrong. It seems people who don't understand basic Physics or who haven't driven manual transmission in many years forget things. Here's a very simple way to picture the concept I present: riding the clutch.<br />
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When you were a beginner manual transmission driver, the fear you had while stopped on a hill is rolling back and hitting the car behind you. What you did (or what I did) was to partially engage the clutch while revving the engine so that the car doesn't roll back. Obviously, this wears out the clutch very quickly. What is significant is that you are accelerating via fighting gravity through clutch slip and higher power of the engine than idle can provide.<br />
<br />
For steeper hills, you needed higher RPM. 45 degree hill would be about the maximum on most cars due to traction. Then the power needed would be? Physics homework for you! If the hill is 90 degrees and there is traction (fly paper tires?), you'd need 1G of acceleration to avoid rolling back.<br />
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The proposal I make in this post is simply "riding the clutch" taken to extreme levels. We know that it can be done at lower power levels; beginners do it all the time. The question of whether it can be done at extreme level requires (expensive) experiments. At least the calculations I present show that it's possible. Now I need to go find girlfriends with ChemE and bunch of Corvettes. BRB.<br />
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<b>Edit: 2016-10-20</b><br />
<br />
There's no question that Corvette has enough power to out accelerate Tesla P90DL with proper abuse of the clutch. But the question was if the tires can hold traction. There's an excellent video by Engineering Explained that stock tires probably won't hold traction, and limit it to about 0.8g in RWD cars like Corvette. That is probably why Corvette is rated only for 2.95 sec 0-60 MPH, and even that's very optimistic.<br />
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<iframe width="320" height="266" class="YOUTUBE-iframe-video" data-thumbnail-src="https://i.ytimg.com/vi/TjQIH_M5R3w/0.jpg" src="https://www.youtube.com/embed/TjQIH_M5R3w?feature=player_embedded" frameborder="0" allowfullscreen></iframe></div>
<br />
Video does an excellent explanation of normal force and shifting center of mass. With shorter wheelbase, peak acceleration would be much higher. That's why lateral acceleration (as in cornering) on Corvette is 1.2g and probably far larger than linear acceleration since width of the car (left to right) is much shorter than length (front to rear).<br />
<br />
So the conclusion is that Stock Corvette will not out accelerate Tesla P90DL only due to lack of traction. But given flypaper tires of infinite traction, (if there is such a thing), appropriate clutch abuse (and destruction) would allow Corvette to out accelerate even P100DL that's rated for 0-60 MPH in 2.5 seconds.<br />
<br />
Many arguments given by EV folks that gas cars lack "instantaneous torque" or that gear shifting make them slow are not true. Rather, gas cars are slow for most parts due to drivers' inability or unwillingness abuse the car to the extreme. Even with capable driver (aka, abuser), traction limit would not allow stock gas cars' tires on RWD configuration to be quicker than intelligent AWD Tesla.<br />
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Which begs the question, is there a tire combination that will allow properly abused Corvette to be quicker than P90DL or even P100DL? I really need to make more money if I'm to satisfy my curiosity. I should setup a "go fund me" page asking for tens of billion dollars so I could take over GM to be able to run these experiments. Anyone care to donate GM to me?sparkevhttp://www.blogger.com/profile/04362518920979349841noreply@blogger.com4tag:blogger.com,1999:blog-6875771813122616391.post-61203092155613435832015-10-28T15:35:00.000-07:002015-10-31T10:30:27.158-07:00Love letter to Nissan Leaf DCFC usersThis love letter is for those who care how Leaf is charging using DCFC. I
hope to save money for those who pay to DCFC, and have non-paying Leaf
drivers be aware how expensive it can be and hopefully become better members of the EV community. This is as romantic as I get, right to the point!<br />
<br />
Previously, I've harped on Leaf's "No charge to have other people wait while Leaf is slow charging" program as well Leaf's slow DCFC speed. I call waiting for Leaf DCFC when L2 would be cheaper as getting "Leafed" and waiting for Leaf DCFC slower than L2 speed as getting "Leafracked". I also call Leaf drivers pulling into and using dual head DCFC when perfectly working Chademo is sitting empty as "Leafrackers".<br />
<br />
<a href="http://sparkev.blogspot.com/2015/10/jerks-all-around-us-iced-leafed.html">http://sparkev.blogspot.com/2015/10/jerks-all-around-us-iced-leafed.html</a> <br />
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There's not much I can do about Leafrackers. They are truly mouse frackers, and I don't have much love for them. Don't be a Leafracker!<br />
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I don't have much love for getting Leafracked, either. If they're willing to take up a DCFC spot and have others wait while charging slower than L2, they are frackers. Especially bad are those who plug in after their first DCFC when they already have 90% SoC. But there could be some that don't really understand that they're charging so slowly.<br />
<br />
While I don't like getting Leafed, those who let others get Leafed may not have much choice. If Leaf battery has deteriorated so much that they cannot get much further than 50 or 60 miles, they may need all the help they can get. Leaf at 60% may only charge at 36kW (instead of 45kW). Even if they pay for charging, they may have to stick around and pay at higher rate until there's enough charge, though switching to L2 at 10kW (80%) instead of 6.6kW (86%) would be nice.<br />
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Below are two tables of MPG equivalent to gas car if Leaf has to pay to charge using eVgo OTG plan. It's similar to my MPGe table in that rows are $/gal of gas at local gas station. It uses Leaf's 114 MPGe EPA (3.38 mi/kWh EPA). Reds represent worse than 50 MPG, though many are masked by light yellow row markers.<br />
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First table is useful for Nissan Chademo only charger. It is more informative charger, because it shows the current in amps. The voltage is roughly constant at 400 volts, so the second column header (second row) is corresponding power in kW (multiply current by 400 divide by 1000), just for FYI. To find equivalent MPG to gas car, simply look up the closest gas price and current.<br />
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For example, if it's 25 amps (about 80%), local gas prices are $2.60/gal (Oct. 2015), you'd be paying equivalent to 14.6 MPG gas car.<br />
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<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgB-VUmz_p9NYV-5OuVvk_JzrARlcqKxPNg21xXAt_9ZpjdmSdQt4wIdovJr76zY1Wr-gZI2qj_0daPSecF94-7nvsM0f84b7ErQA0bfaaJJeLis5GDMicjAr98OFDda0TU1z10XHnECSaM/s1600/leaf_evgo_mpge%2524_1.gif" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgB-VUmz_p9NYV-5OuVvk_JzrARlcqKxPNg21xXAt_9ZpjdmSdQt4wIdovJr76zY1Wr-gZI2qj_0daPSecF94-7nvsM0f84b7ErQA0bfaaJJeLis5GDMicjAr98OFDda0TU1z10XHnECSaM/s1600/leaf_evgo_mpge%2524_1.gif" /></a></div>
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<br />
Second table is useful for dual head ABB charger. It's not as good, because it does not show power nor current. As such, we have to "eye-ball" and infer the data we need. One can deduce power from energy (kWh) and elapsed time. 0.01kWh in 1 second would correspond to 36kW, 2 second would be 18kW, 3 seconds 12kW, 4 seconds 9kW, and so on. In general, if it takes more than 2 seconds for 0.01kWh (18kW), it's better to disconnect and use L2 instead. That's only with regard to time if others are waiting. If money is your objective, it's better to move to L2 when it takes more than 1 second per 0.01kWh (about 60%)<br />
<br />
One can deduce more accurate kW from ABB by doing time averaging. For example, one can count how many seconds it took to get 0.1 kWh, and divide the time by 10 to get more accurate time for 0.01kWh. Because Leaf slows down so quickly, much longer averaging many not be beneficial, although if you're trying to charge at 95% (hopefully, no one's waiting for you), you may have to wait for about 4 minutes to get 0.1 kWh.<br />
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For example, if it's taking 3.5 seconds for 0.01kWh and local gas prices are $2.60/gal (Oct. 2015), you'd be paying equivalent to gas car between 13.2 MPG and 17.6 MPG.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEizwIA3yhNElQjj870Ghh32dgG9JnoRKA_oJoPMDHcogbPNhmJE6_5KkSq1KXt-Rv0o_T84nzcjde_raZZV1Dqv62BLSVtscnvYp2hLgJd8IE8e6glESvYGaYP5nVeEAUwh7KffTbRzJG7z/s1600/leaf_evgo_mpge%2524_2.gif" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEizwIA3yhNElQjj870Ghh32dgG9JnoRKA_oJoPMDHcogbPNhmJE6_5KkSq1KXt-Rv0o_T84nzcjde_raZZV1Dqv62BLSVtscnvYp2hLgJd8IE8e6glESvYGaYP5nVeEAUwh7KffTbRzJG7z/s1600/leaf_evgo_mpge%2524_2.gif" /></a></div>
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<b>Edit Oct 29, 2015</b><br />
<br />
A commenter by the name of Todd was gracious enough to make measurements of Leaf DCFC, and made a plot of Power vs elapsed time. Following is a quote of his comment.<br />
<br />
"The battery was at 24% at start and ended at 88% in 30 minutes. The temperature here in Mira Mesa was 70 degrees @ 10PM. The battery started at 70 degrees and ended at 87 degrees. The rate was 41Kw, increasing to 44Kw until around 58% charge and then it was a somewhat linear drop to about 9Kw over the last 21 minutes. That works out to 34% in the first 9 minutes and another 30% in the last 21 minutes. The last image is showing the voltage of each cell and SOH%."<br />
<br />
From what little research I did, GIDS (named after a guy who made Leaf tool?) is actual battery capacity that is used whereas SOC (state of charge) is absolute battery capacity. Like all EV, the battery does not discharge to 0 and does not charge to 100%. When 0% is indicated by the car, there's still lots of energy in the battery. GIDS is what's indicated by the car. As such, SOC is pretty meaningless with regard to driving; only GIDS will be discussed. In fact, when I use SOC in my blog, what I really mean is GIDS.<br />
<br />
The plot was made at ambient temperature of 70F, so it's hard to know how it'll translate at different temperatures. It may not be absolutely accurate for all conditions, but it's a guide to make some rule-of-thumb observations to help Leaf drivers.<br />
<div>
<br /></div>
<hr />
<br />
<div class="separator" style="clear: both; text-align: left;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiqgNYlsSIHeWLaPQnHua-e37-ZMDvD9pAjatexr8CguNqTz5-z9u7bFyfOx9UyJ3BMQeExbK-u0ZSG1WMAeLUCTXNJ1Bs4caQxtuWLdZYEykAbuhXO9lYrc7aQOv0W3dKNM9hA3u8dEGy7/s1600/Charging+graphs_1.gif" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiqgNYlsSIHeWLaPQnHua-e37-ZMDvD9pAjatexr8CguNqTz5-z9u7bFyfOx9UyJ3BMQeExbK-u0ZSG1WMAeLUCTXNJ1Bs4caQxtuWLdZYEykAbuhXO9lYrc7aQOv0W3dKNM9hA3u8dEGy7/s1600/Charging+graphs_1.gif" /></a></div>
<div>
<div>
Left axis is power in kW for Green plot. Right axis is % for GIDS in magenta, battery state of charge in % in red, not sure what black is; maybe temperature?</div>
<div>
</div>
<br />
1. If you're paying eVgo OTG plan to charge, and you have 6.6kW L2, it's best to switch to L2 at 40kW (100A current) to minimize cost. That occurs at about 60%. If you have 3.3kW L2 (2012 and earlier), it's best to switch to L2 at 20kW (50A current), which occurs at about 75%.</div>
<div>
<br /></div>
<div>
2. If you want to optimize for time, the best place to disconnect is when it starts to dip below 40kW, which is about 60%.</div>
<div>
<br /></div>
<div>
3. If you want to optimize for time, and you need more than 60%, it's up to the individual when to stop, but it seems the "knee" occurs around 70%.</div>
<div>
<br /></div>
<div>
4. If you need more than 70%, time taken will be less than optimal, but it will be quicker than L2 up to about <strike>88</strike> 85%, taking 15 minutes to gain 15% (averaging about 1% per minute, VERY SLOW!). This would be the maximum charge Leaf should get from DCFC. <strike>It's easy to remember: back to the future! Get it? Time optimized, back to the future 88? Yeah, go see the movie!</strike> (based on Tom Saxton's data, 88% might not be best; stop at 85%. See below)</div>
<div>
<br /></div>
<div>
<div>
5. Based on his charging from 24% to 88% in 30 minutes, you should prorate your charging accordingly. Best would be to plug in at 10% or less to get to 70% in 30 minutes (roughly). But if you're already at 50%, you should only take about 10 minutes to 70%, not full 30 minutes. No-charge-to-charge or not, waiting around to charge wastes time, and I'm sure your life is worth more than $1/hr.</div>
<div>
<br />
<b>Edit Oct. 30, 2015</b><br />
<br />
As I was researching "GID", I came across another blog (by Tom Saxton?) that deal with Leaf DCFC.<br />
<br />
<a href="http://www.saxton.org/tom_saxton/2012/06/dcqc-roadtrip.html">http://www.saxton.org/tom_saxton/2012/06/dcqc-roadtrip.html</a> <br />
<br />
As a test, he charged from 21% to 80%, then plugged in again to get 95%. Hopefully, others weren't waiting while he was doing this! I think he got clever with axis labels. He states he charged to 80%, yet the light blue is "pack kWh" in legend. I suspect he cleverly chose the axis so that %GID and pack kWh line up. As such, pack kWh plot will be used as %GID.<br />
<br />
For 21% to 80%, he found it to take 13.2kWh in 26:40 min (0.44 hours). That's 30kW on average, which is roughly similar to eye-balling from Todd's plot. That's also 44MPGe$ from first table above when gas prices are $2.60/gal.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://www.blogger.com/goog_2049685832" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhP78bbk2rlUzBHAc1t1SANq7lZxbRZhcJTDGfG_aMQN6eHoHg8YNhMSN4H4B5u5_yEaR8pLHriT5kHnl0-uD7sOd9z18xfHfUuGGq9NQurWV92ZdlDQgNvL6t3j5FgeMLz5a6kbpHS3PT5/s1600/DCQC-80.gif" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><a href="http://www.saxton.org/tom_saxton/photos/dcqc/DCQC-80.gif">http://www.saxton.org/tom_saxton/photos/dcqc/DCQC-80.gif</a></td></tr>
</tbody></table>
<br />
For 80% to 95%, he found it to take 3.2kWh in 36:35 min (0.61 hours). That's 5.25kW on average, far less than Leaf's L2. That's about 7.5MPGe$ from second table 5.1kW column when gas prices are $2.60/gal.<br />
<br />
Far more troubling is what happens at 88%. Basically, it stops charging for 8 minutes while you're paying by time; $0.80 gone to dollar heaven! In addition, first 3 minutes of charging adds more energy than 33:35 min after. This is probably what I saw some Leaf at >90% charging less than 2kW with DCFC. Talk about wasting time!<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://www.blogger.com/goog_2049685839" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEidksZ_g6VPh9PHrMDhO0zKb6mq7ER1hYQO_VMHtawfsiVqUZGcA0fH-F0G1jdoKBhTsIASd97Ve61XI0IsrSgXgL4_0KMh_jfedoNX6TrUk0WnAxW6dmcs_D5sP3z5K3g6wJ7vtjI9JLL5/s1600/DCQC-80-100.gif" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><a href="http://www.saxton.org/tom_saxton/photos/dcqc/DCQC-80-100.gif">http://www.saxton.org/tom_saxton/photos/dcqc/DCQC-80-100.gif</a></td></tr>
</tbody></table>
<br />
Based on this data, maximum recommended DCFC level would be 85% (3% margin from 88%). Otherwise, you risk being in charging limbo at 88% for 8 minutes. But you should still disconnect at 60% (40kW) or 70% (~20kW "knee" region of slowing) if you can live with it. After all, why waste time and money needlessly?<br />
<br /></div>
</div>
sparkevhttp://www.blogger.com/profile/04362518920979349841noreply@blogger.com4tag:blogger.com,1999:blog-6875771813122616391.post-88436105148445384872015-10-24T23:28:00.000-07:002015-11-09T13:29:15.846-08:00Jerks all around us: ICED, Leafed, Leafrackers<div>
NOTE: It came to attention that "Leaf**k" is not safe for work (NSFW). Taking cues from Battlestar Galactica, all instances of "Leaf**k" has been replaced with Leafrack.<br />
<br />
We sometimes think that we're a small community of EV drivers. If you ride a motorcycle, you know the feeling; we wave to each other, knowing that death may fall on us the very next minute by an errant douche, and genuinely glad to see a fellow motorcyclist. For EV, some Dicks (Richards?) may decide to cut all EV programs. When EV drivers meet at fast charger, where we sometimes stick around since it often only takes 10 or 15 minutes (except Leaf), we make a friendly chat as kindred spirits. But the world is not as such. There are plenty of jerks around.</div>
<div>
<br /></div>
<b>Leafed and Leafracked</b><br />
<div>
<div>
<br /></div>
<div>
If you are unable to charge, because there's Leaf charging at rate slower than 6 times L2 rate (6*6.6kW = 40kW), then you're getting Leafed. Why 6 times? Because DCFC is 6 times more expensive than L2, and people who have to pay for charging would disconnect if DCFC gets slower than 6 time L2 rate. But hold on. You might ask, "why do you call it getting Leafed when all EV slow down charging as the battery fill up?"</div>
<div>
<br />
First reason to calling it Leafed is that Leaf's fast charging is not very fast compared to SparkEV (and probably all other EV since only Leaf lacks thermal management). It starts out fast enough, but it slows down very quickly. Since Leaf gets below 40kW even when they have 60% state of charge, you're probably getting Leafed any time there's a Leaf in fast charge spot. Some Leaf slow down to as low as 2kW from 50kW charger!</div>
<div>
<br /></div>
<div>
<a href="http://sparkev.blogspot.com/2015/05/vs-nissan-leaf-quick-charge.html">http://sparkev.blogspot.com/2015/05/vs-nissan-leaf-quick-charge.html</a></div>
<div>
<br /></div>
<div>
<div>
Let me pause here and tell Leaf drivers how DCFC pricing works,
because I've heard comment that "it's the same thing at 1kW or 100kW,
because electricity is charged per kWh." eVgo charges electricity by
time, not energy: $0.10/minute ($0.20/min for non-OTG plan). The longer
you're plugged into the charger, regardless of kWh of energy used, the
more money you pay. Therefore, the slower you charge, the more expensive
it gets for energy. Meanwhile, L2 is $1/hr, 1/6 as expensive per time as DCFC.<br />
<br />
How expensive can DCFC get? At 6kW
(Leaf DCFC at 88%, which almost all Leaf I've seen go beyond), you'd be
paying about $1/kWh (or $2/kWh for non-OTG plan). With $2.60/gal gas prices
these days, you'd be paying more than 10.5MPG gas car (or 5.25MPG gas car
for non-OTG plan). At 2kW (some Leaf at 95%), you'd be paying more than 3.5MPG gas car (or 1.75MPG gas car for non-OTG plan). Those are using SparkEV
efficiency figures; Leaf could pay even more due to lower efficiency.<br />
<br />
<a href="http://sparkev.blogspot.com/2015/05/spark-ev-miles-per-gallon-this-table.html">http://sparkev.blogspot.com/2015/05/spark-ev-miles-per-gallon-this-table.html</a><br />
<br />
Which brings to second reason to calling it Leafed. Leaf drivers use fast charger to charge slower than their 6.6kW L2, because Nissan gives out free charge for 2 years. They call it "no charge to charge" program. I call it "no charge to take up fast charge spot and have everyone wait while slow charging" program, because Leaf charges so slowly. Since it's free, Leaf drivers don't care that they're charging slower than L2 or plug in when they already have 90% charge in battery to take up full 30 minutes and charge at 2kW (worse than 1.75MPG gas car). After all, why bother spending the time to move the car to L2 when it slows down when fast charge is free for them?</div>
</div>
<div>
<br /></div>
<div>
We have various degrees that we can distinguish for getting Leafed as follows. The percentage numbers are from few observations I made of Leaf battery state of charge and corresponding charging speed. Percentages will vary depending on ambient temperature and how hard Leaf was driven before plugging into fast charger and other factors.</div>
<div>
<div>
<br /></div>
<div>
Greater than 40kW (0% to 60%) = A OK, Normal charging.</div>
<div>
40kW to 6.6kW (60% to 88%) = Getting Leafed.</div>
<div>
6.6kW to 1kW (88% to 100%) = Getting Leafracked (Leafed and fracked)<br />
<br />
Almost all Leaf I've encountered at DCFC Leafracked others to some degree, including other Leaf.</div>
</div>
<div>
<br /></div>
<div>
<b>SparkEVed not likely, i3ed but never fracked</b></div>
<div>
<br /></div>
<div>
Since all EV slow down as the battery is filled, the problem is not unique to Leaf. But Leaf is most abundant source of the problem due to its slow charge and free charge. For example, getting SparkEVed would entail the following. SparkEV has 3.3kW L2, so the thresholds would be 20kW and 3.3kW.</div>
<div>
<br /></div>
<div>
Greater than 20kW (0% to 92%) = A OK. Normal charging.</div>
<div>
20kW to 3.3kW (92% to 100%) = Getting SparkEVed.</div>
<div>
SparkEV charges at 9kW at 99%, so there's no way to get SparkEVed and fracked.</div>
<div>
<br /></div>
<div>
Since it gets more expensive as it gets slower than 40kW, SparkEV driver would disconnect as close to that as possible (about 85%), so one isn't likely to ever get SparkEVed. However, BMW gives free charge, so one may encounter "i3ed", although not likely to get fracked at the same time since they charge fast enough. Getting regularly Leafracked can only come from Leaf. </div>
<div>
<br /></div>
<div>
Getting Leafracked is bad for all EV, including Leafs. If a Leaf driver is waiting to charge, and there's a Leaf already there, chances are he's getting Leafed, and probably getting Leafracked half the time. Basically, getting Leafed sucks the life out of all of EV community, including Leaf.</div>
<div>
<br /></div>
<div>
<b>Leafrackers</b></div>
<div>
<br /></div>
<div>
I mentioned in previous posts about Leaf taking a dual head CCS-Chademo charger while perfectly good Chademo charger is next to it. I call them Leafrackers. You can read about my first encounter with a Leafracker. Scroll down in the link below.</div>
<div>
<br /></div>
<div>
<a href="http://sparkev.blogspot.com/2015/10/free-charging-sucks.html">http://sparkev.blogspot.com/2015/10/free-charging-sucks.html</a></div>
<div>
<br /></div>
<div>
It is not the same as finding a Leaf charging from dual head while Chademo charger is empty; it could be that when the Leaf first pulled up, Chademo was being used. Since the driver wouldn't be around, there would be no way to move it after Chademo freed up, so that would be a legitimate use of the charger. Even if the driver is around after Chademo subsequently became empty, not moving the car is acceptable; I mean, if the driver had gone to eat while charging, you wouldn't expect to drag him out of the restaurant to move the car. It would be nice for him to move the car (LeafSaint?), but not bad if he doesn't.</div>
<div>
<br /></div>
<div>
The specific incident when you find a Leafracker is when you observe someone pulling into dual head charger when the working Chademo charger is empty. As such, finding Leafracker is rare, since you must witness it.<br />
<br />
Or is it? Was that really the first time I encounter a Leafracker in my post? I've seen many Leaf charging from dual charger while Chademo was empty, but I always assumed that there was another using Chademo when they pulled up. After all, why would they purposely use dual head and block CCS when perfectly good Chademo is available? I mean, EV people are nicer than that, right? Don't we meet the nicest people in EV?</div>
<div>
<br /></div>
<div>
<a href="http://sparkev.blogspot.com/2015/05/you-meet-nicest-people-in-ev.html">http://sparkev.blogspot.com/2015/05/you-meet-nicest-people-in-ev.html</a></div>
<div>
<br /></div>
<div>
Just today (Oct 24, 2015) as I was charging, a Leaf pulled up and tried to use the dual head charger when Chademo was empty. Now I'm not so sure if Leaf people are as nice as rest of EV people. Based on this, I suspect there are many more Leafrackers than we realize. Maybe even most of those incidents when I saw Leaf using dual head chargers were Leafrackers, not merely having Chademo already taken when they pulled up. Of course, there is no way to know; I'm just getting paranoid.<br />
<br />
Leafrackers are most damaging to CCS cars such as SparkEV and eGolf.
But the wait caused by CCS can lead to waits for subsequent EV, including other Leaf. That actually happened in the case I mention in my first encounter with Leafracker. My 30 minutes of getting Leafracked by Leafracker resulted in 16 minutes of wait for another Leaf. Besides, when you have EVs needlessly waiting around to charge, it's bad for entire EV community reputation. Gas bags would say, "EVs will never work. Just look at them waiting to charge even when EV is tiny percentage of gas cars."</div>
<div>
<br />
<b>Not only Leafracker</b><br />
<br /></div>
<div>
You might say that Leaf isn't the only Chademo charging car. That is true. One can theoretically encounter iMievfrackers or SoulEVfrackers. But in reality, Leaf is the only Chademo car that gives free charging, and they are far more likely to plug into the fast charger at high state of charge and keep it plugged in due to Leaf's slow charging.<br />
<br />
When iMiev or SoulEV plug in, they are likely to do so only when absolutely necessary since they must pay. They are also likely to reduce their time at the charger since slowing charging as battery accumulates more energy means far more money out of pocket. It's like the sound falling tree makes in the forest when no one's around; there may be iMievfrackers and SoulEVfrackers, but if you don't encounter them, their impact is irrelevant. Meanwhile, I've encountered real life Leafrackers, maybe many, many of them.<br />
<br />
<div>
<b>ICED</b></div>
<div>
<br /></div>
<div>
If a car is
parked in EV charging spot while it's not charging, and you are unable
to charge, then you have been "ICED". ICE stands for Internal Combustion
Engine. In the early days of EV (circa 2011), there were very few EV
public charging, and most of those blocking EV charging spots were (are)
gas cars (ICE cars). That's where the term comes from. Obviously, if a
gas car parks in EV charging spot, you cannot charge, so you would be
ICED.</div>
<div>
<br /></div>
<div>
But today, there are many
EV (in SoCal). Some who drive EV treat EV charging spots as privileged
EV parking spots instead of charging spots. I have been ICED by TeslaS
parked in CCS charger spot. I waited about 30 minutes until he came out,
and I told him not to park at charging spot since he cannot use CCS
charger. His response? He just went in the mall to get something quick,
and there was no other parking. Bull! There were plenty of parking, but
CCS spot happened to be closest to the shop he wanted to visit. Yes, you
can get ICED by Tesla. Those with expensive cars shouldn't piss off
those who drive cheap cars.</div>
<div>
<br /></div>
<div>
I was
told by a BMW i3 driver that a Volt was parked in fast charger spot. I
presume Volt was not charging, because she said she was ICED by Volt. If
Volt was not plugged in, it would be ICED. But if Volt was plugged in,
but full and taking spot to prevent others from charging, would that be
ICED? I think it would be. But if Volt is charging at L2, but taking
fast charge spot making others unable to fast charge, would that be
ICED? No, because he is charging. But I'd call him a Voltfracker.</div>
<div>
<br /></div>
<div>
In
another incident, there was Fiat500e using L2 charger at fast charger
spot with the L2 cord stretched out far. It's impossible to know why she
did that, but I suspect she just got the car, and didn't know what
parking stall to use. She had dealer temporary tag made on the previous
day. I think she'll learn to use proper spot in the future; I mean,
there's no point in charging farther away from the charger than
necessary when all she can use is L2. Still, if one cannot use the fast
charger, because someone is using L2 at fast charger spot, would that be
ICED? That would be similar as Volt case above: Fiatfracker (Sergio is a special kind of Fiatfracker).</div>
<div>
<br /></div>
<div>
L2
EV purposely preventing fast chargers while themselves are charging at
L2 is rare. I've never encountered it. However, I have seen them ICE the spot
(ie, they're not charging).</div>
<div>
<br />
<b>State of the jerks address</b><br />
<br />
<div>
New York Times had an article on just this topic: EV jerks. They
did not explain what chargers were having issues, but it sounded like
all of them were L2 at workplace or other form of free charging. Getting Leafracked and Leafrackers are rare since there are fewer DCFC relative to L2, although I seem to be getting Leafracked every time I have to wait for a charger.</div>
<div>
<br /></div>
<div>
<a href="http://www.nytimes.com/2015/10/11/science/in-california-electric-cars-outpace-plugs-and-sparks-fly.html">http://www.nytimes.com/2015/10/11/science/in-california-electric-cars-outpace-plugs-and-sparks-fly.html</a></div>
<div>
<br /></div>
Frankly,
I'm surprised that there aren't fist fights or even gun fights breaking
out over public L2 and free charging. If someone unplugs public L2,
that could mean hours of lost time; may even have to spend the night at
the office, call a cab, or, heaven forbid, ride the bus! In a world
where people drive half way across town to save $0.01/gal of gas,
they'll go to even more extremes when it's free.<br />
<div>
<br /></div>
<div>
The
problem with public L2 will only get worse. There is no way to meet the
demand no matter how many are put in, especially when it's free, because not
everyone uses assigned charging spots. As such, some locations will
have more EV than public L2 during certain times, and others will be
left empty. If they can get off the charger quickly, problem is less.
But L2 takes hours.</div>
<div>
<br /></div>
<div>
Combined this
with more jerks adopting EV, and the problem will be severe. Gun fight
will break out. And no, banning guns won't work. By the way, definition
of assault weapon is "scary looking gun, typically used in movies", and
not much to do with its function.</div>
<div>
<br /></div>
<div>
The
solution? DCFC, but with penalty for using it for longer time. But for
now, we have to deal with jerks. Maybe there's few, maybe there's many,
but what is certain is that more will be adopting EV. Hopefully, this post illuminates the problems facing us, and solutions will be implemented in the future to prevent jerks from EV getting ICED, Leafed, Leafracked, and Leafrackers.<br />
<br />
<b>Edit Oct. 26, 2015</b><br />
<br />
As I was perusing comments section in Plugshare for a place I charged, I came across comments from a 2014 Leaf owner. Apparently, he is aware of the problem, though i don't know if he links it to free charging or if he'd appreciate those bad behaviors being called "getting Leafed / Leafracked". He also had to use dual head charger few times when his card did not work in Chademo only unit; that doesn't make him Leafracker; he at least tried to use Chademo but failed.<br />
<br />
Knowing that there's at least one like him, I have some hope. I wish there are more like him. I also wish he's a she, not a he. :-) Following are some of his comments out of several dozen of them.<br />
<br />
"Oh my god! Same guy from before who plugs and charge for 30mins on the Chademo,comes back to his car and replugs his car again even if he is already above 95%. White SL leaf with no license plate yr 2012."<br />
<br />
"Have to wait for this guy for 20 mins before his 2nd session on the chademo terminal is over. He should have just plugged in to the lvl 2 port instead if he wanted to top off."<br />
<br />
"Lvl 2 charger can deliver 3.95kWh in 30 minutes. For a 2014 SL LEAF that's 16%. Please use it as a guide especially if you're close to 80% charge already and wanted to get close to fully charge. Instead of using the DC fast charge."<br />
<br />
<b>Edit Nov. 9, 2015</b><br />
<br />
After getting heavily Leafracked (waiting 20 minutes for a Leaf at > 90% charging slower than cold molasses in Arctic winter), I wasn't in any chipper mood for another Leaf. After about 5 minutes into my charging, another Leaf pulled up and said in chipper voice, "it's a busy night" to which all I grunted out was "it sure is". Well heck, if it weren't for getting Leafracked by the first Leaf, it wouldn't be that busy!<br />
<br />
Another few minutes later, a BMW i3 pulls up. Since there were only 2 fast chargers, he had to wait. Few minutes later, the Leaf driver comes out and unplugs his car and tells the i3 driver "I'm at 70%, and I can come back later. Why don't you charge your car now?" WOW! This guy is LeafSaint placing the need of others above his!<br />
<br />
Or is he? Maybe he knows that Leaf charges slower after 70%, so he decided to unplug to save his time. Or maybe he read / heard that some guy writing SparkEV UNOFFICIAL Blog has been nagging about getting Leafed and Leafracked.<br />
<br />
Actually, it doesn't matter why he did that, but that he did give up his charging as it's slowing down. He is LeafSaint whichever way you look at it. A huge thank you, and the very first LeafSaint award of the month goes to you!<br />
<br /></div>
</div>
</div>
</div>
sparkevhttp://www.blogger.com/profile/04362518920979349841noreply@blogger.com3tag:blogger.com,1999:blog-6875771813122616391.post-87810354438650119212015-10-22T10:25:00.000-07:002015-11-18T15:02:16.163-08:00Money MPGe$ for various EVNOTE: For our metric friends, L/100km$ tables follow the MPGe$ tables in bottom half of this post.<br />
<br />
I established true out of pocket cost MPGe using actual measured data early in my blog. After all, the amount of money I pay compared to gas car is what matters to me, and probably to most people as well.<br />
<div>
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<a href="http://sparkev.blogspot.com/2015/05/spark-ev-miles-per-gallon-this-table.html">http://sparkev.blogspot.com/2015/05/spark-ev-miles-per-gallon-this-table.html</a></div>
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I used to think that everyone knew this, but apparently, most people were (are?) oblivious to it; they believe they're getting 100+ MPGe, because EPA tells them so. While that's true with regard to energy consumption, that's not what most people are expecting. When they hear MPG, they think of the money they'll spend / save. Telling people that EV gets 124 MPGe is committing fraud without telling them that MPGe doesn't have much to do with money.</div>
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<a href="http://sparkev.blogspot.com/2015/09/mpge-fraud.html">http://sparkev.blogspot.com/2015/09/mpge-fraud.html</a></div>
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In this post, I present various tables that show out of cost MPGe (MPGe$) for various cars. For SparkEV, I was able to measure the actual mi/kWh, and have an accurate table in link above. But for other cars, I have to infer mi/kWh from EPA's MPGe figure.</div>
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First, these are EPA MPGe converted to mi/kWh using </div>
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mi/kWh = MPGe / 33.7kWh/gal</div>
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Note that mi/kWh inferred from EPA is about 20% lower for SparkEV compared to actual measured mi/kWh. Therefore, it could be that other cars also have higher mi/kWh when actually measured. In any case, the table should give you an idea of MPGe$, which you can boast (or feel shamed) when speaking with gas car drivers for apples-to-apples comparison.</div>
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<a name='more'></a>To read the table, rows are $/gal at local gas station and columns are $/kWh you pay to charge the car. For example, $2.60/gal gas in SoCal on Oct 2015 and $0.33/kWh a household would pay for $150/mo electric bill would result in 29 MPGe$ for BMWi3, 20.8 MPGe$ for Tesla P90D. Those are far away from EPA's 124 MPGe and 89 MPGe for those cars.</div>
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Even the best case of $2.80/gal premium gas and $0.19/kWh for SDG&E base rate would result in 54.2MPGe$ for BMWi3, still far, far away from EPA's 124 MPGe. SoulEV with EPA 105 MPGe would only get 46 MPGe$, worse than Prius using premium fuel! But again, this is using EPA's "mystery meat" MPGe figure; actual could be bit better (10% to 20%?)</div>
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Last column of $0.59/kWh is what Blink charges for their DCFC if you're a member; you get less than 20MPGe$ in most cases. For those who pay $2/kWh (Leaf at 88% battery at DCFC, non OTG plan), you can take $0.25/kWh MPGe$ and divide by 8; with $2.60/gal, you'd be getting about 4MPGe$.<br />
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Green is 75 MPG boundary (2001 Honda Insight), orange is 50 MPG boundary (Toyota Prius), red is 25 MPG boundary (typical gas car).</div>
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Money equivalent to liters per 100km for our Metric friends. Conversion factor used from MPGe$ to these values are 100/1.609344.<br />
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Because row and column units are the same, if you stick to same currency denomination, the math works out. For example, if it's BMW i3 with Euro 0.19/kWh and Euro 1.50/Liter, you would be paying equivalent to gas car that gets 2.14 L/100km.<br />
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Green is 3.14 L/100km boundary (2001 Honda Insight), orange is 4.7 L/100km boundary (Toyota Prius), red is 9.41 L/100km boundary (typical gas car in US).<br />
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Why is this color scheme seem different (prettier?) than MPGe$? It's done by comparing successive rows whereas MPGe$ color is done by comparing successive columns. This has to do with row resolution being less in L/100km tables to cover more range (about $2/gal to $12/gal).<br />
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sparkevhttp://www.blogger.com/profile/04362518920979349841noreply@blogger.com0tag:blogger.com,1999:blog-6875771813122616391.post-52585609877785592052015-10-21T12:20:00.000-07:002015-11-09T13:38:48.698-08:00Radio interference by Leaf or Chademo or ?I sometimes listen to AM radio. While most of it's junk, there's a show called "Tim Conway Jr. Show" on KFI 640AM. One of their programs is called "What the hell did Jesse Jackson say?" where callers hear a snippet of some speech by Jesse Jackson and try to guess what he said. It is HILARIOUS! No, I don't think it's racist, although I wish he'd have other hard to understand figures, such as "George Bush" specials; I mean, it's NU-CLEAR, not NU-QULAR.<br />
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I was listening to this show one night while fast charging, and the radio went bonkers all of a sudden. It was not static, but some sort of buzzing (PWM?) that completely wiped out the reception. I didn't know what it was at the time. Oh well, back to audiobook.<br />
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In another time, as I was pulling into charge with the AM radio playing with Leaf already charging, I noticed that buzzing got worse as I got closer. Then it dawned on me; it's Leaf charging. Over the next few weeks, I observed that interference was not only from Chademo only charger (Nissan made?), but dualhead ABB charger as well when Leaf was plugged in.<br />
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So the culprits for the interference could be any combination of the following: Chademo standard; Chademo chargers (Nissan and ABB); Leaf <br />
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Unfortunately, this will come across as Leaf bashing, but that's not the case. If I encounter other EV and I remember to test the AM radio, I would. But these days, it seems only EV using fast chargers are Leaf. If you happen to see EV charging, please try to test the AM radio. <br />
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More unfortunately, BMW i3 in US does not come with AM radio (supposedly, EU version does), so they can't test it. I3 drivers are missing out on a very entertaining show!<br />
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By the way, please don't go complaining to some government agency if you find interference. If you'd like to complain, you can put comments below or contact the companies. I'm hoping the industry will fix itself if there's a problem rather than involving the big brother.<br />
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<b>Edit Nov. 9 2015</b><br />
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As I was waiting to charge next to a Leaf (getting Leafracked; >90%, slower than molasses in Arctic winter) and a SoulEV, both using ABB chargers, I was able to listen to the AM radio. This was in LA where the station is based, and there was no interference! It seems the interference problem is not universal, and strong AM signal could result in no discernible interference from Leaf.<br />
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But in San Diego, the radio is clear as in LA. The signal may be weaker, but the AGC (automatic gain control) of the radio would compensate. If there is much stronger interfering source, such as charger and/or Leaf, it would wipe out the signal. Unless there is a way to determine RSSI (received signal strength indicator), it would be difficult to know when the interference would be so bad as to wipe out the radio. I suppose I could get some Ferrite loop and make crude spectrum analyzer and ...<br />
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NO NO NO. I am not getting involved, despite how tempting the dark side may be!<br />
<br />sparkevhttp://www.blogger.com/profile/04362518920979349841noreply@blogger.com0tag:blogger.com,1999:blog-6875771813122616391.post-53036734787776427342015-10-07T13:56:00.001-07:002015-10-20T08:15:13.527-07:00Free charging SUCKS!If something is free or low cost while the supply is limited, it gets sold out and shortages result. Unintended consequences result, often at terrible outcome. For example, during storms, people buy stuff they may not necessarily need to have, but just in case they need it. Because the stores cannot raise prices to discourage "just in case" buying, they inevitably run out. Then the people who desperately need those items cannot buy them at any price, even if that item could save lives.<br />
<br />
This is the (HUGE) problem with free fast charging programs offered for BMW i3 and Nissan Leaf. They offer 30 minutes of free fast charging for a year or two. Since fast charging is free, the drivers use up all the time they can, whether they need it or not. This results in waiting in line, sometimes for hours, for everyone. Since Nissan Leaf is most widely available EV, they cause the most problem. Compounding the problem is Leaf's slow DCFC rate. <br />
<br />
<a href="http://sparkev.blogspot.com/2015/05/vs-nissan-leaf-quick-charge.html">http://sparkev.blogspot.com/2015/05/vs-nissan-leaf-quick-charge.html</a><br />
<br />
They have 79% state of charge (SoC)? Plug it into DCFC and wait 30 minutes to get 95% SoC. Then plug it in again for 30 minutes to get to 99% SoC. Then plug it in again and go shopping for yet another 30 minutes to get 100% SoC, never mind that 100% was reached after 5 minutes. Hey, they are entitled to 30 minutes, and it's free. Why not?<br />
<br />
Above is an extreme example, of course. But the problem is that every charging session becomes 30 minutes instead of 5 or 10 minutes of pick me up. Now multiply this 30 minutes by every Leaf and i3 owner, and you can see the problem. Why charge with L2 when 30 min DCFC is free? Who cares if DCFC is only charging at 1kW when 30 min DCFC is free? Why charge at home or at work when 30 min DCFC is free? Why wait until I'm below 80% when 30 min DCFC is free?<br />
<br />
WHY CHARGE AT ANYWHERE ELSE OR ANYTHING LESS THAN 30 MINUTES WHEN 30 MIN DCFC IS FREE?<br />
<br />
The problem is made worse by Leaf's slow charging. If it would charge like SparkEV (45kW to 80%, taper to 9kW at 99%), guys who plug in with 80% SoC may be done after 10 minutes. But with charging slowing down so quickly, I've never seen a Leaf reach 100% SoC on DCFC. This means every DCFC by "no charge to charge" result in 30 minutes of waiting.<br />
<br />
Meanwhile, guys who have to pay (SparkEV, eGolf, etc) pay attention
to how we're charging. DCFC is 6 times more expensive than L2, so it's better to disconnect and use L2 when it gets slower than 40kW (6.6kW * 6) or 20kW for 3.3kW L2 chargers like SparkEV. Also, MPGe could cost more than 1 MPG gas car if we let it sit. Basically, EV that pay to charge do not hog the charger, because there's penalty for doing so. That penalty can be very steep if we let it sit.<br />
<br />
<a href="http://sparkev.blogspot.com/2015/05/spark-ev-miles-per-gallon-this-table.html">http://sparkev.blogspot.com/2015/05/spark-ev-miles-per-gallon-this-table.html</a><br />
<br />
If there are enough chargers to go around, this is not a problem. But at key places like intercity areas such as "Shops" in Mission Viejo or Carlsbad Mall to get to LA/OC/SD, they are almost always occupied, even at late night. This makes for waiting for 2 or 3 Leafs before being able to charge, sometimes 2 hours of waiting.<br />
<br />
Following are some personal experiences. One Leaf was charging at less than 2 kW with 10 minutes left to go at Carlsbad mall with 3 other cars waiting. Another Leaf at "Shops" was charging at 3 kW with 2 other cars waiting. Another Leaf at San Diego was charging at 4 kW at 95% with 1 other car waiting. You can read about how I determine the rate by reading my previous post.<br />
<br />
<a href="http://sparkev.blogspot.com/2015/05/vs-nissan-leaf-quick-charge.html">http://sparkev.blogspot.com/2015/05/vs-nissan-leaf-quick-charge.html</a><br />
<br />
Here's a quote from plugshare comment.<br />
<br />
"Great selection of charge plugs. The 50W CHAEDMO stooped charging at 85%. We needed more and charged second time. Starbucks in walking distance."<br />
<br />
Obviously, she charged for 30 min to 85%, then another 30 min (to 95%?) while away at Starbucks! I have to wonder if she knew she's charging slower than L2, and whether there were others waiting, or they saw that it's occupied and left in frustration. She could've saved others' time by switching to L2. I don't know if Leaf would charge as high as 6.6kW using L2 at 85%SoC, but it certainly wouldn't take any more time than DCFC. But hey, DCFC is free, why not hog the spot?<br />
<br />
If you're coming fresh into EV, you hear "30 minutes fast charge!" and think that it'll be 30 minutes. But when 30 minutes typically turn into 1.5 hours (wait for 2 other cars ahead with "no charge to charge"), it makes for sour EV experience, especially when you really need it for those rare intercity travel. It gets very frustrating. Am I going to get another EV, even the upcoming 200 miles range one, and put up with this crap or just get a gas car?<br />
<br />
If I'm a conspiracy theory kind of a guy, I'd say Nissan and BMW are deliberately trying to kill EV adoption by giving "no charge to charge".<br />
<br />
As much as I hate free stuff causing shortages, they could've implemented as "free to 80% SoC". That way, only the fast charging portion of fast charging would be free. It would also discourage abuse by those charging at 90% SoC to try to get to 100%. But of course, there may be other issues, such as regulatory hurdle in only allowing pricing by time, and pricing by energy to be illegal. So maybe there is bigger conspiracy by the government along with Nissan and BMW to kill EV adoption with "no charge to charge" program.<br />
<br />
<b>Edit 2015 Oct. 17</b><br />
<br />
As I was pulling in to charge, there was a Leaf that just plugged into dual charger and the driver ready to leave to go shop. Meanwhile, the dedicated Chademo was left empty. I politely explained how there's dual head and asked her if she can move the car so I don't have to wait 30 minutes for her car to finish. She said she just plugged in, and didn't feel like moving the car! I was going to dish it, but I didn't want to make a scene.<br />
<br />
After she left, I saw her Leaf's state of charge in the beginning: 76%! It started out quick enough, but soon it was charging at 16kW. At 90%, it was charging less than 6 kW (taking over 6 seconds for 0.01kWh as shown in the video) with 11 minutes left to go. This is slower than L2 charging speed while she's taking dual-head fast charge spot. <br />
<br /><br />
<div class="separator" style="clear: both; text-align: center;">
<iframe allowfullscreen="" class="YOUTUBE-iframe-video" data-thumbnail-src="https://i.ytimg.com/vi/DHrUoITe77I/0.jpg" frameborder="0" height="266" src="https://www.youtube.com/embed/DHrUoITe77I?feature=player_embedded" width="320"></iframe></div>
<br />
"I'm entitled to free 30 minutes. Whether I'm charging slower than L2
using dual head fast charger when I could've used Chademo doesn't
matter. I'll take this spot even if I don't charge!"<br /><br />
Meanwhile, a Kia SoulEV pulled into Chademo only slot after about 20
minutes into her charging. Few minutes after I started my charge,
another Leaf pulled up. Then the offending Leaf driver came back to move
her car some 40 minutes later. Because she wasted 30 minutes of my
time, second Leaf now has to wait for me to charge. I go to 80% (it gets
expensive beyond that), so it only took 16 minutes. Had the offending
Leaf moved her car to Chademo charger in the beginning by spending 2
minutes, I would've saved 30 minutes, the next Leaf would've saved 16
minutes. Senseless waiting all around.<br />
<br />
THANK YOU LEAF FOR NO CHARGE TO TAKE FAST CHARGE SPOT WHILE SLOW CHARGING!<br />
<br />
Free
charging is not only bad, but it fosters non-caring and entitlement
attitude. This can only go bad to worse for EV adoption.sparkevhttp://www.blogger.com/profile/04362518920979349841noreply@blogger.com16tag:blogger.com,1999:blog-6875771813122616391.post-74864206025198773652015-09-30T23:30:00.000-07:002015-09-29T07:36:54.043-07:00Why SparkEV by SparkEV BlogspotAs of Sep. 2015, these are my reasons for SparkEV.<br />
<br />
Look! Out on the road! It's quick! It's quiet! It's SparkEV!<br />
Yes, it's SparkEV. A fantastic EV that's risen from the ashes of crushed EV1. SparkEV, which can out accelerate any new car under $20,000 in 0-60 mph and more efficient than any EV in its class. And who, disguised as a mild mannered five door subcompact car with safety of 10 air bags, fights a never ending battle to reduce importing oil from ISIS, Russia, Venezuela, and EV stereotype of over-priced, under-powered glorified golf cart that can only drive 80 miles a day.<br />
<div>
<br /></div>
<div>
<div>
<b>1. SparkEV costs as low as $13,500, which is cheaper than Spark gas version.</b></div>
<div>
Spark EV MSRP = $25,000 - $7500 (federal tax credit) - $4000 (CA rebate) = $13,500</div>
<div>
Spark gas MSRP with automatic transmission = $15,100</div>
<div>
*note: Income greater than 3 times poverty level qualify for only $2500 CA rebate. 3X poverty level is about $45,000/yr for single, bit over $60,000 for family of 3. Income greater than $250,000/yr do not qualify for CA rebate.</div>
<div>
<br /></div>
<div>
<b>2. SparkEV lease could cost less than $1,500 used car.</b></div>
<div>
SparkEV GM factory lease of $139/mo for 39 months with zero down = $5421</div>
<div>
CA rebate = up to -$4000 (-$2500)</div>
<div>
Total lease cost = $1421 ($2921)</div>
<div>
*note: New car insurance is higher, but that's offset by fuel savings and practically zero repair and maintenance of SparkEV. Individual savings will vary depending on used car's condition, insurance premium, driving habits, and subsidy eligibility.</div>
<div>
<br /></div>
<div>
<b>3. SparkEV is quickest new car under $20,000 in 0-60 mph, EV, gas, diesel or anything else.</b></div>
<div>
SparkEV = 7.2 seconds ($13,500)</div>
<div>
Mazda 3 with 2L engine / automatic = 7.7 seconds ($19,995)</div>
<div>
VW Jetta with 1.8L Turbo / automatic = 7.4 seconds ($22,815)</div>
<div>
<br /></div>
<div>
<b>4. SparkEV is quickest EV under $30,000 in 0-60 mph.</b></div>
<div>
SparkEV = 7.2 seconds ($13,500)</div>
<div>
Mitsubishi i-Miev = 13.0 seconds ($23,000-$11,500=$11,500)</div>
<div>
Fiat 500e = 8.7 seconds ($32,600-$11,500=$21,100)</div>
<div>
Nissan Leaf = 9.4 seconds ($32,950-$11,500=$21,450)</div>
<div>
BMW i3 = 6.5 seconds ($43,395-$11,500=$31,895)</div>
<div>
Tesla P90D = 2.8 seconds ($119,200-$11,500=$107,700)</div>
<div>
<br /></div>
<div>
<b>5. SparkEV is most efficient EV under $30,000 (lowest use of imported oil) .</b></div>
<div>
SparkEV = 119 MPGe ($13,500)</div>
<div>
Mitsubishi i-Miev = 112 MPGe ($23,000-$11,500=$11,500)</div>
<div>
Fiat 500e = 116 MPGe ($32,600-$11,500=$21,100)</div>
<div>
Nissan Leaf = 115 MPGe ($32,950-$11,500=$21,450)</div>
<div>
BMW i3 = 124 MPGe ($43,395-$11,500=$31,895)</div>
<div>
Tesla 70D = 101 MPGe ($75,000(?)-$11,500=$63,500)</div>
<div>
*note: US electric grid is energy independent in that it uses virtually no imported energy. Oil is up to 60% from imported sources (in 2006) such as Russia, Venezuela, Saudi Arabia, and "blame" Canada.</div>
<div>
<br /></div>
<div>
<b>6. SparkEV can fast charge 80% in 20 minutes (able to drive over 1,000 miles in single day).</b></div>
<div>
SparkEV with fast charge option = Combined charging system fast charge (CCS)</div>
<div>
Fiat 500e = no fast charge available</div>
<div>
Mercedes B class = no fast charge available</div>
<div>
Nissan Leaf with fast charge option = Chademo fast charge</div>
<div>
BMW i3 = Combined charging system fast charge (CCS)</div>
<div>
Tesla Model S = Tesla Super charger</div>
<div>
*note: 65 mph driving for 1 hour and 10 minutes to get off/on highway and 20 minutes to charge, get food/coffee, use bathroom would result in 44 mph average speed. 24 hours would result in theoretical 1056 miles. Without fast charge, even 130 miles would take upwards of 8 hours. Fast charge is a must for any EV.</div>
<div>
<br /></div>
<div>
<b>7. SparkEV uses smallest battery in EV that gets over 80 miles range per charge.</b></div>
<div>
SparkEV = 19.5 kWh, 82 miles range</div>
<div>
Fiat 500e = 24 kWh, 87 miles range</div>
<div>
Nissan Leaf = 24 kWh, 84 miles range</div>
<div>
BMW i3 = 22 kWh, 81 miles range</div>
<div>
Tesla P90D = 90 kWh, 300 miles range</div>
<div>
Chevy Bolt = ??? (50kWh? 200 miles range?)<br />
*note: Small battery means potentially lower replacement cost after warranty period of 8 years. It is estimated that Lithium battery raw material prices are around $100/kWh, an eventual lowest cost for battery.</div>
<div>
<br /></div>
<div>
<b>8. SparkEV uses thermal management (liquid cooling) for battery.</b></div>
<div>
SparkEV = liquid cooled thermal management</div>
<div>
Nissan Leaf = blow hot air</div>
<div>
Tesla P90D = liquid cooled thermal management</div>
<div>
*note: Liquid cooled thermal management increases battery longevity and faster charging by better dissipating heat generated by charging and discharging process.</div>
<div>
<br /></div>
<div>
<b>9. SparkEV is safe, practical, and works well with fostering homeless dogs.</b></div>
<div>
SparkEV = 5 doors, 10 air bags (think of Pathfinder landing on Mars), high head room</div>
<div>
Fiat 500e = 3 doors, difficult rear seat access when used with doggie barrier</div>
<div>
Tesla P90D = would you want to have its leather interior covered with dog hair, windows splattered with drool, and sand on floor/seats from dog beach?</div>
<div>
*note: Volunteer to foster homeless dogs and/or adopt foster dogs. It's a rewarding experience for humans and saves dogs' lives. SparkyV will thank you.</div>
<div>
<br /></div>
<div>
<b>10. SparkEV has been sold out in much of So Cal since about mid May 2015. Reason is obvious; it's the best car for the money, EV or gas. Grab'em if you can before they sell out again!</b></div>
<div>
<br />
If you want to see how SparkEV stacks up against other EV, see<br />
<br />
<a href="http://sparkev.blogspot.com/2015/09/ev-ranking.html">http://sparkev.blogspot.com/2015/09/ev-ranking.html</a><br />
<br /></div>
</div>
sparkevhttp://www.blogger.com/profile/04362518920979349841noreply@blogger.com4tag:blogger.com,1999:blog-6875771813122616391.post-49614238418062215442015-09-26T16:03:00.000-07:002015-10-02T10:36:57.734-07:00Imported oil geo-politics: SparkEV, the car that will save the worldNot all oil is the same. One crucial aspect is that imported oil can come from ISIS, Russia, Venezuela, and, heaven forbid, "blame" Canada. While overall imported oil is about 30% in 2014, it was as high as 60% in 2006. But as an individual, we use particular type of oil for our vehicles. Since refineries can't use any oil (ie, light sweet vs tar sand), they use about 60% from imported sources. What this means is that you're directly paying ISIS and "Terence and Philip eh? eh?" Canadians with up to 60% of what you pay at the pump. Yes, the ISIS bullet that killed Syrian kids probably came from your pocket if you pumped gas.<br />
<br />
<rant><b> </b><br />
<b>Oil wars are not for oil</b><br />
<br />
Often I hear undeclared subsidy for oil are US wars in middle east. That's nonsense. Oil is secondary pretext for war (primary being democracy, human rights, what have you). Far more plausible underlying reason for war is duping the public into fear and to collect more taxes. If some entity is demonized and we are at war with them, people are more likely to cough up the dough. Follow the money for wars and see who benefits: oil companies or war department?<br />
<br />
About 20% of US budget is for war department (let's call it what it is instead of "defense" department). A budget monster of $650,000,000,000.00 (or much more?) isn't likely to go down without a fight. There's only so much BS they can give during peace time to keep up their budget.<br />
<br />
One way to keep funding during peace time is to demonize another country that we are at peace with at the moment. Now that the cold war is over, we need another. How often do you read about evil China and their military build up? While we spend $650 Billion, China spends $120 Billion, less than 1/4 of what we spend. And why would China go to war with US when US is their largest economic partner? Do they want to commit suicide? If they go to war with US and win, presumably to take over US, then what? Are they going to "manage" US as well as they're doing now with China having 1/8th the per capita GDP of US? This is complete nonsense, but many seem to believe it.<br />
<br />
If boogeyman fear isn't enough, a far more effective way to keep/boost war funding is to have some convenient wars here and there to remind the population that boogeyman is still out there and real. Of course, the pretext has to be something like human rights and other nonsense. Occasionally, they slip up, like George H.W. Bush said about the first gulf war being about oil. But if oil did not matter, we'd still have wars, whether it's North Korea or Cuba (before 2015) or Congo or where-ever else we deem convenient to keep the war funding increased. As such, war for oil is false pretext, and oil means nothing when it comes to wars.<br />
<br />
But hypothetically, let's assume war was for oil. Shouldn't US benefit from those wars? Why import when we can simply take over the oil fields? Some argue that is happening and all the profits are going to oil companies. As public company, they have to release their books, and you're free to examine them. Then some say those books are cooked. So then the question for them would be, "what would convince you that the wars are not due to oil?" Typically they say, NOTHING could convince them that war's not for oil! Yes, this is straw-man argument, but I haven't heard any good argument for the reason for war is oil while actual beneficiaries are war department cronies.<br />
<br />
Most recent war is "war on terror", not oil. When does this war end? When all terrorists are killed? Well, no. This war will go on FOREVER! Pretext for war against terrorist is complete nonsense, just like war for oil is nonsense. The real reason for war is to keep the public in fear so they can collect more taxes.<br />
<br />
In a related note, if you think more taxes will help schools and roads, think again. Schools and roads take tiniest of tiny chunk of the tax money compared to war department. Far better idea is to fight to reduce taxes while changing the budget for more productive use. While I dislike subsidies, EV subsidy to get off importing oil is worthwhile endeavor. Economic war on importing oil via subsidy is something I don't mind fighting; nobody dies in this war. In fact, it will save lives via reduced pollution in populated areas as electric generators tend to be in less populated areas.<br />
<br />
If war isn't for oil, then why do we care about oil? I might as well
drive a Ferrarri that gets 8 MPG, right? No, we care, at least a little, because what's done
with the money we pay at the pump. 9/11 was the result of using oil; if we did not give so much money to Saudis for oil, bin Laden probably wouldn't have so much money to fund terrorists, let alone buy a camel for himself. If not for oil, they'd have to do something more productive; with vast Saudi desert, could they be the leader in solar technology today? It's hard to say.<br />
<br />
9/11 is just the recent past, but what of the future? As we pour more money into cleptocracies and crazies (ie, Venezuela), we're just inviting more nut jobs. Will one of them take the oil money that you gave at gas station and buy asmall nuclear bomb or plutonium dust and explode it in middle of Manhattan? If we continue to fund wackos, that will happen, not if but when. It doesn't guarantee that won't happen if we don't use oil. However, it is far more likely when they have the money but without much else to do other than digging holes in the ground for oil.<br />
<br />
I only touched on this topic. As you look around the world, you will see that oil exporting countries generally lack intelligence (Norway is a rare exception with Qatar trying but failing). They don't produce much other than oil. Who could blame them? Money is pouring in from all corners of the world just by digging holes in the ground. Why should they risk technological development and risk making less money?<br />
<br />
That, of course, doesn't mean their population fare well. One only has to look to Venezuela, one of the most oil-rich nation in the world and how poor the people are; as with other oil rich nut jobs they blame other countries for their ills. And finally, one can't forget Canada, a morally corrupt country that gave us "Terence and Philip" along with their tar sands.<br />
</rant><b> </b><br />
<br />
<b>Peak oil and scarcity</b><br />
<br />
A very important fact
to remember is that fossil fuel, including oil, should be considered
virtually unlimited resource in free market economics. While this may
seem obvious to econ (homo-economicus), this fact is lost on many, so
I'll try to explain it.<br />
<br />
Oil is the result of millions
of years of dead organic material. Earth had organic matter for roughly a
billion years while humans have been using it for about 100 years. Yes,
not all of that billion years' worth is available as fossil fuel. But
as simple estimation, it's hard to say that we've used many, many orders
of magnitude of production in such short time. Indeed, we haven't used
much in grand scheme of things, and we're not likely to run out any time
soon.<br />
<br />
Oil is only scarce due to its price. The
so-called "peak oil" is only with respect to technology and cost of
exploration, not necessarily due to physical scarcity. If oil cost
$1000/gallon, and people must use as much as they do now, companies will
find lots of oil, even in so-called no-oil countries like Japan and
Korea. If oil is free, not much oil will be found; there's no reason to
do so, but there will be constant shortages due to everyone clamoring
for freebie oil. In the real world, if oil cost goes up to $1000/gallon,
people will simply not use oil. Instead, companies will invent
alternatives. Heck, even at $3/gal for gasoline, people like me are
driving EV primarily as cost cutting measure. <br />
<br />
<b>Fossil fuel Politics</b><br />
<br />
Politics play a huge role in oil pricing, which is another way of saying how much oil is available, so one must discuss politics when discussing availability of oil. Gas is sold with heavy taxes, but producing oil is done with subsidy. This keeps oil exploration and production cheap while artificially keeping the price high at the pump. Overall effect on price compared to free market without subsidy and taxes, according to wikipedia, is probably not much. Since overall effect on price would be about the same without subsidy and tax, they are promoting oil exploration without increasing pump prices. But think about it. Government is subsidizing BP, Exxon, etc. while taxing you and me. While the effect on price to you and me may be benign, there's something distasteful about taking money from individuals to give to multinational corporations. This is a rare moment when I'm not a homo-economicus.<br />
<br />
Now let's assume there's no subsidy for production, but the tax for consumption (you and me) is kept. Prices will go up due to lower production, although it's hard to tell if other nations will boost production and to what degree. But more importantly, this will result in less oil exploration in US and more imported oil. Worse, higher prices may lead to less demand, but that extra money will go to foreign sources. Do you feel comfortable giving more money to ISIS and Putin when you pump gas? As distasteful as subsidy is, I prefer subsidy over more imported oil.<br />
<br />
Now let's assume there's subsidy for production and no tax for consumption. In CA, tax alone could lower the gas price by almost $1/gal. People will simply use more. Eventually, the price will stabilize, but it will again increase imported oil to meet the demand at least for short term, if not forever. Once again, more money to ISIS and Putin. As much as I hate taxes, it might be worse without it in case of oil.<br />
<br />
But what if both subsidy and tax are cut? Will it really result in roughly similar pump prices? It's hard to say, but as wikipedia states, "probably". Trying to cut through the tangled mess of regulation is "probably" impossible, but it's probable that there will be less domestic oil. Yes, they can sell for higher prices, but it'll probably cost less to simply import oil than to explore for more domestic sources. Again, more money to ISIS and Putin.<br />
<br />
As an extreme measure, the government can put price control (like in socialist countries) on selling oil. This actually happened during oil crisis in 1970's. As with most (all?) price controls, results were shortages and long line. Combine long lines / shortages with tariff on imported oil and higher taxes for oil production could reduce oil use. There's only so many times one would wait 2 hours to get gas before saying "fuck you. I'm getting a SparkEV which is ready to go in 20 minutes". But there are inevitably unforeseen consequences to price control and shortages: "fuck you. I'm going to steal gas from you." (ie, black market).<br />
<br />
You can also try increasing the subsidy and/or increasing the tax. But they inevitably could (COULD!) result in more imported oil. One measure could be tariffs on imported oil, but that could spark a whole new can of worms as demonstrated by 1930's great world-wide depression. (Nazi Germany had almost 0% unemployment during this time, but that means little in terms of quality of life) So no matter what we do in terms of subsidy and tax, it's bad? Damned if we do, damned if don't? What do we do?<br />
<br />
<b>Answer to world peace</b><br />
<br />
One possible solution would be to use less oil while keeping both the subsidy and tax the same. According to EIA.gov, while 30% of oil is from imported source (60% in 2006), refineries use roughly 60% of oil from imported source. In other words, gas and diesel at the pump are made with 60% from imported oil, and paying at the pump is the same as directly giving lots of money to ISIS. This is due to inability to refine light-sweet-crude and thick tar at the same time, and they must optimize for one or the other. This doesn't mean driving 60% more efficient car (ie, 70 MPG) will eliminate imported oil as the cut in demand will also impact domestic producers. But it will reduce the amount of imported oil. Whether the refineries will remain at 60%, go up or down is impossible to say. What matters is the amount of money paid to foreign producers is reduced. Hugo Chavez would be turning over in his grave if US could do this.<br />
<br />
Of course, cutting oil is easier said than done. How? EV, of course! Unlike gas/diesel, US electricity production is from domestic sources (US electric grid is energy independent). Even with dirty coal, natural gas, nuclear, EV is far more benign to the world geopolitics than oil. A side benefit to this is that 10% to 60% of electricity comes from renewables sources such as solar and wind. While I don't think pollution benefits of renewables are major selling point, not importing oil and technology behind them that add to collective human intelligence is certainly more desirable than digging holes in the ground.<br />
<br />
<b>SparkEV, the car that saved the world</b><br />
<br />
We narrowed it down to EV as the solution. But not just any EV will do. One can pay $135,000 and drive Tesla P90D, but not many have that much money laying around. Far better is to have something low cost that's affordable by the masses and desired by them by better performing than comparable cars. Even Nissan leaf fails in this regard due to higher price and poorer performance than comparably priced gas cars. I'm afraid upcoming Chevy Bolt and Tesla Model 3 will suffer similar deficiencies.<br />
<br />
There's only one at this time, and that is SparkEV. It's cheaper, quicker, and more economical to operate than any comparably priced car, gas, diesel, or EV. With fast charging, it's a practical car that can be driven hundreds of miles in a day if needed. GM should crank out millions of SparkEV like VW did with their 60+ years production run with their beetle while continually cutting costs using economy of scale.<br />
<br />
<a href="http://sparkev.blogspot.com/2015/09/ev-ranking.html">http://sparkev.blogspot.com/2015/09/ev-ranking.html</a><br />
<br />
If GM wants to be patriotic American company, the best thing they can do is build and market more SparkEV and make it easier for people to drive it (ie, DCFC in all their dealers, but not free). If GM wants to be known as a company that saved the world, they should sell SparkEV throughout the world that are energy independent in electricity. Imagine what history would say if everyone drove SparkEV: SparkEV, the car that saved the world.<br />
<br />sparkevhttp://www.blogger.com/profile/04362518920979349841noreply@blogger.com0tag:blogger.com,1999:blog-6875771813122616391.post-49130241915206997412015-09-26T12:29:00.001-07:002016-01-31T09:25:48.142-08:00EV rankingAs with all engineering projects, EV is a matter of trade off. Any old fool can make an EV that gets 1000 miles range per charge or 0-60 mph time of 2 seconds with enough money. EV that cost millions of dollars each is not a good EV. You can't just look at single metric and say that's good (or bad) EV. <br />
<br />
SparkEV does well in individual rating, such as second most efficient EV behind BMW i3, and third quickest EV from 0-60 mph behind Tesla S and i3. It is also lowest cost EV that gets 80 miles or more range. But how good is it with respect to cost? What we need is an objective metric to determine what good EV means with pricing as a factor. How objective are these? It's my blog, I can make up whatever I want. But I'll try to be fair.<br />
<br />
<b>Range-cost metric</b><br />
<br />
Like stock price P/E ratio, range per dollar is helpful. I use post subsidy cost. Since most EV buyers take full subsidy, I call this the real world cost. Indeed, Tesla falls to the bottom half when measured this way. There are few web sites that discuss pre-subsidy range/$ that show Tesla to be the top followed by SparkEV. Such is nonsense, of course. Why wouldn't you take the subsidy? Buying EV without subsidy makes no sense when they are currently available.<br />
<br />
To clarify such rampant misinformation, here's a ranking of some popular EV based on range/$ metric post subsidy. Subsidy is assumed to be $10K ($7.5K fed, $2.5K CA, although it could be as high as $4K for low income CA and $2250 out of $3K in MD). Only cars with DC fast charging are on this list. I consider EV without DCFC as toys, not serious vehicles. Yellow (jersey as in bicycle race) highlights the best.<br />
<br />
<iframe height="300" src="https://docs.google.com/spreadsheets/d/1C3hOTvZ0lSUneuKXJS4bQ2oYpkz16YusUEJjzsk_YTQ/pubhtml?gid=0&single=true&widget=true&headers=false&chrome=false" width="100%"></iframe>
<br />
<br />
"Toys" not worth considering<br />
<br />
Fiat 500e<br />
Ford Focus Electric: 76 miles / $20K = 3.8<br />
Leaf S without DCFC option<br />
Mercedes B class<br />
Smart ForTwo EV<br />
SparkEV without DCFC option: 82 miles / $15K = 5.47<br />
Toyota Rav4EV: 113 miles / $40K = 2.83<br />
Golf cart: 10 miles / $5K = 2.00<br />
Used Golf cart with new battery: 10 miles / $2K = 5.00<br />
Really beat up old golf cart with new battery: 5 miles / $1K = 5.00<br />
<br />
Few interesting observations can be made.<br />
<br />
1. SparkEV is clearly on top of the pack with good margin. SparkEV is even better than low cost golf cart in range-cost metric. Golf courses should just let people drive SparkEV instead of golf carts. Maybe GM could add "golf-cart mode" for just such purpose to limit speed and acceleration, although marketing might be problematic given how "sporty" SparkEV is.<br />
<br />
2. 2016 Leaf SV/SL with longer range is something to behold. It's the first EV under $30K to break the 100 miles per charge barrier. With widespread Chademo DCFC, it's probably second best EV on the market today (SparkEV being top). If you're not in moderate weather areas (eg. AZ), Kia Soul EV would be a better choice due to its thermal management.<br />
<br />
3. Which brings to attention Kia Soul EV. I test drove it in Drive Electric event, and it is ok. Being used to mashing the accelerator in SparkEV and feeling the rush, Soul EV lacked soul. If it's not for Leaf SV/SL 110 miles range, Kia Soul EV would take the second place.<br />
<br />
4. Tesla S70 is a surprise. I had expected it to be in top half, but it's in bottom half. In that regard, it doesn't make sense to get base model S. Either go for P90D for performance or skip Tesla altogether.<br />
<br />
5. BMW i3 is a huge surprise to me. It's a great car with good performance and features similar to SparkEV. Alas, its high price makes it, well, high priced. Long ago, I had considered BMW i3 to be better version of SparkEV, but it seems that's not the case; SparkEV is leagues ahead of BMW i3.<br />
<br />
6. At the bottom, I add Bolt / Model 3, both of which are vaporware for now. I mean, Chevy won't even let you sit in one at autoshow. Still, this shows how SparkEV would hold up in the future: not as good, but that's expected.<br />
<br />
Clearly Bolt/Model 3 wins over SparkEV, right? But hold on. While exact spec isn't known, one can guess that battery will be bigger (50kWh?), hence the replacement cost to be at least $5,000 after warranty expires after 10 years. This assumes battery prices have come down to $100/kWh (from about $300/kWh today) after 10 years, probably the best case scenario considering that raw material prices are around $100/kWh. One can look today to see how many people spend $5,000 to fix a broken down 10 year old car: not many, if at all. In comparison, SparkEV with 19.5 kWh battery could cost less than $2,000. Lots of people spend $2000 to fix 10 year old car.<br />
<br />
What this comes down to is the resale value of 10 year old car. In case of Bolt/Model 3, car is basically junk. Entire cost is sunk. But in case of SparkEV, car would be fixable with reasonable cost and re-sold as used and driven for another 10 years. One can play the game that used battery could cost less or that shorter range could still be sold as used car. Well, I guess we'll have to wait and see: definite lower practical cost of SparkEV or some nebulous hocus pocus for much bigger battery EV. In my opinion, bird-in-hand wins even over vaporware promise, so SparkEV still wins the crown as best EV, even against 200 miles range per charge EV.<br />
<br />
<b>Performance-cost metric</b><br />
<b><br /></b>
One can also try another cost metric, such as $ to 0-60 mph time. Again, one can put 9999 horsepower motor with 1 kWh battery and get 0-60 mph in 2.2 seconds, but that probably won't cost $16K. As expected, SparkEV wins this one hands down, too. At this point in time, only SparkEV and Tesla P90D are worth discussing as they are only two that can compete (and beat) other cars in their price range, but let's see few others. BMW comes close, but there are other cars in its price range that are quicker. I also add Corvette in the mix, a decent gas car with limited utility. Metric is time-$ product where smaller is better. Yellow (jersey as in bicycle race) highlights the best. Let the battle begin!<br />
<br />
<iframe height="300" src="https://docs.google.com/spreadsheets/d/1C3hOTvZ0lSUneuKXJS4bQ2oYpkz16YusUEJjzsk_YTQ/pubhtml?gid=1976315597&single=true&widget=true&headers=false&chrome=false" width="100%"></iframe>
<br />
<br />
As I was putting together the data, I noticed SparkEV is far above anything else as shown in 0-60 time-cost product (almost 2.6 times more bang for the buck than P90D and Corvette!). I decided to square the time to give advantage to P90D. Hey, it's my blog, I'll tweak the figure to favor another vehicle if I want to! But even then, SparkEV comes out ahead. Only when you cube the time does P90D gets better than SparkEV.<br />
<br />
<b>Range-</b><b>performance</b><b>-cost</b><br />
<div>
<br /></div>
<div>
<div>
Let's try something little more convoluted by combining 3 metrics. EV with longer range, short 0-60 time, low cost is good. Then the equation used is </div>
<div>
<br /></div>
<div>
R / (t * $) where R=range, t=0 to 60 time in seconds, $ is real cost post subsidy.</div>
<div>
<br /></div>
<div>
where resulting larger number is better EV.</div>
<div>
<br /></div>
<div>
<div>
<iframe height="300" src="https://docs.google.com/spreadsheets/d/1C3hOTvZ0lSUneuKXJS4bQ2oYpkz16YusUEJjzsk_YTQ/pubhtml?gid=2022746562&single=true&widget=true&headers=false&chrome=false" width="100%"></iframe>
</div>
<div>
<br /></div>
<div>
This formula produces result that I like. <strike>SparkEV, like other cost metrics, comes out on top. Yawn; what else is new? But Tesla P90D is close second. </strike>(This was when I erroneously used $145K for P90D. Despite being second fiddle to P90D, it's nipping at its heels!)<br />
<br />
Other popular EV are clustered around 400 mark. A surprise is VW eGolf worse than i-MiEV. Maybe it's not a huge surprise given that it's very similar to Leaf with higher cost.<br />
<br />
Another interesting bit is Bolt/Model3. While specs aren't out, <strike>it could be roughly on par with P90D. </strike>(Again, when I wrongly had P90D at $135K) If they can bring the price down (not likely) or quicker 0-60, it could be competitive to SparkEV. How quick? 9.3 seconds. That should be doable. But even that won't compare to SparkEV single metric of 7.2 seconds. Would you buy $30K car that performs poorer than $16K car? I think I'm going to be keeping my SparkEV even after Bolt/Model3 comes out.<br />
<br />
<b>Range-performance-battery-cost</b><br />
<br />
As discussed before, smaller battery is better due to potential for lower replacement cost. While it doesn't impact the car when new, it will have large effect when it comes time to replace it 10 years later. This also affects whether the car will end up in the junk yard (more pollution and energy use) or repaired and continue to drive.<br />
<br />
R / (t * B * $) where R=range, t=0 to 60 time in seconds, B is battery capacity in kWh, $ is real cost post subsidy.<br />
<br />
<iframe height="300" src="https://docs.google.com/spreadsheets/d/1C3hOTvZ0lSUneuKXJS4bQ2oYpkz16YusUEJjzsk_YTQ/pubhtml?gid=1427058934&single=true&widget=true&headers=false&chrome=false" width="100%"></iframe>
<br />
Yet again, SparkEV wins. Not surprisingly, Tesla P90D is at the bottom due to its large battery. The question for P90D owners is if they're willing to spend $9000+ for a 10 year old car? Of course, Tesla offers optional battery replacement plan, but I don't know how many take up on their offer and continue to pay for 10 years. Given that P90D is not a typical consumer car, I suspect many will opt to keep it running by spending $9000+, and not throw it in the junk yard.<br />
<br />
In case of SparkEV, like P90D, it can out accelerate comparable cost gas cars, so spending $2000 to replace the battery may be worth it. I have a feeling SparkEV will become collector's car if it's not mass produced by Chevy.<br />
<br />
But what about other EV that are inferior performing to comparable gas cars like SoulEV and Leaf SV/SL or even i3? Would you spend $3000 for a 10 year old car that's slower than gas car counterparts and doesn't even have liquid cooled thermal management in case of Leaf, especially when there will be new EV with 200+ miles range that perform better? I have a feeling they will end up in junk yard, causing more pollution and energy waste than comparable gas car where you can spend couple of thousand dollars incrementally to drive another 10 years rather than one lump sum battery replacement.<br />
<br /></div>
</div>
</div>
<b>Other-cost metrics to consider</b><br />
<b><br /></b>
Another comparison could be efficiency-cost metric, and one can see SparkEV wins this hands down due to being second most efficient EV (119 MPGe) behind BMW i3 (124 MPGe) while costing less than half.<br />
<br />
Unfortunately, I don't have ready source of information on other metrics such as skid pad and slalom data. Considering SparkEV battery weighs less than 500lb and sitting low (typical EV), I suspect it would handle well, too, although stock tires would have to be changed. <br />
<br />
Still, I'm curious what legitimate cost metric SparkEV would be less than another EV. Taking the cube of 0-60 mph time doesn't count. 3.3kW charger vs 6.6kW charger would be one, but that means little when DCFC is available. 4 hours for 24kWh Leaf at 6.6kW vs 6 hours for 19kWh SparkEV at 3.3kW makes virtually no difference when they are used at work (8 hours) or home (12 hours). In fact, it would be better if there's 2.2kW charger for SparkEV so that I can leave the car plugged in while at work rather than moving it half way through the work day.<br />
<br />
Actually, there is one metric where SparkEV definitely lose. It's been sold out for many months! Maybe it's a sign that SparkEV is destined to become a collector's car.<br />
<br />
<b>Edit Oct. 28, 2015</b><br />
<br />
Nissan Leaf (even 2016 with 110 miles range) does not have thermal mangement. That results in poor battery longevity, and very poor DC fast charge performance. I've seen several Leaf charging at 2kW out of 50kW fast chargers! Such slow charging is bad for Leaf drivers, but also bad for all EV who have to wait for Leaf to charge. I've harped on this many times in my blog.<br />
<br />
<a href="http://sparkev.blogspot.com/2015/05/vs-nissan-leaf-quick-charge.html">http://sparkev.blogspot.com/2015/05/vs-nissan-leaf-quick-charge.html</a><br />
<br />
<a href="http://sparkev.blogspot.com/2015/10/free-charging-sucks.html">http://sparkev.blogspot.com/2015/10/free-charging-sucks.html</a><br />
<br />
<a href="http://sparkev.blogspot.com/2015/10/jerks-all-around-us-iced-leafed.html">http://sparkev.blogspot.com/2015/10/jerks-all-around-us-iced-leafed.html</a><br />
<br />
It has come to my attention that VW eGolf also does not have thermal management. While I don't know if their DCFC would be as slow as Leaf since I've only seen one. But what I know is that lack of thermal management is a risk, not onlyb to battery longevity, but also wasted time at fast chargers both for the eGolf driver and everyone else. One should weigh this "problem" appropriately. If it's up to me, it doesn't make sense to get eGolf with similar specs as Leaf S for $3000 more, but then again, no other EV makes sense for me other than SparkEV.<br />
<br />
Below are some links to eGolf's lack of thermal management.<br />
<br />
<a href="http://www.autoblog.com/2014/03/31/vw-e-golf-will-not-have-active-cooling-system-lithium-battery/">http://www.autoblog.com/2014/03/31/vw-e-golf-will-not-have-active-cooling-system-lithium-battery/</a><br />
<br />
<a href="http://www.greencarcongress.com/2014/07/20140721-egolf.html">http://www.greencarcongress.com/2014/07/20140721-egolf.html</a><br />
<br />
<b>Edit Jan. 31, 2016</b><br />
<br />
While Rav4EV was considered a "toy" above due to lack of DCFC, someone thought it doesn't have to be that way. Tony Williams of quickchargepower.com offers Chademo charging modification to Rav4EV for $3000.<br />
<br />
<a href="http://www.quickchargepower.com/">http://www.quickchargepower.com</a><br />
<br />
That would make Rav4EV pretty compelling. It has small SUV form, range of 113 miles using 42 kWh battery, 0-60 in 7.2 seconds (some say even quicker). While Toyota discontinued Rav4EV at 2014 model year, used Rav4EV are selling for about $25K to $30K. Assuming $30K for used price including Chademo mod, some scores can be given.<br />
<br />
Range / price = 113 / 30 = 3.77 (roughly Tesla S70)<br />
<br />
Performance * price = 7.2 * 30 = 216 (7.2*7.2*30 = 1555, roughly BMW i3)<br />
<br />
Range / (Performance * price) = 113 / 216 * 1000 = 523 (worse than SparkEV, but significantly better than 110 mile range 2016 Leaf SV/SL)<br />
<br />
Range / (Performance * price * battery) = 523 / 42 = 12.5 (roughly eGolf)<br />
<br />
Unfortunately, there are many forum posts (including Tony's) that state Rav4EV suffers from multiple problems, and it may have reliability issues. Since Toyota seem to be abandoning battery EV in favor of other (fuel cell for now), few drivers with Rav4EV seem to be left out in the cold.<br />
<br />
More unfortunately, quickchargepower.com website seem to be out of order. However, I have seen some recent plugshare posts showing success with Rav4EV modified to use Chademo. The user name was Tony, so maybe it was Tony Williams? In any case, used Rav4EV under knowledgeable driver could make it a decent EV with quickchargepower.com's Chademo mod.<br />
<br />
<b>Bolt news</b><br />
<br />
Chevy announced Bolt as 60 kWh battery, 0-60 under 7 seconds, about $30K. One has to guess what "under 7 seconds" means, but SparkEV was promised under 8 seconds to be 7.5 seconds in 2014 model. Let's guess 6.5 seconds for Bolt. That would make the scores as follows.<br />
<br />
Range / price = 200 / 30 = 6.66 (same as my guess)<br />
<br />
Performance * price = 6.5 * 30 = 192 (6.5*6.5*27 = 1268, roughly BMW i3)<br />
<br />
Range
/ (Performance * price) = 200 / 192 * 1000 = 1042 (the best among EV)<br />
<br />
Range / (Performance * price * battery) = 1042 / 60 = 17.4 (roughly BMW i3)<br />
<br />
Of course, these are just guesses. But something that I did not include in the metric is DCFC time. SparkEV is quickest charging EV in the world with 0-80% in 20 minutes. By contrast, Tesla takes nearly 45 minutes for 0-80%. While one might poo-poo percentage as meaningless, that isn't the case when human psychology is involved.<br />
<br />
<a href="http://sparkev.blogspot.com/2015/12/sparkev-is-quickest-charging-ev-in-world.html">http://sparkev.blogspot.com/2015/12/sparkev-is-quickest-charging-ev-in-world.html</a><br />
<br />
Chevy announced that they have no intention of helping expand the DCFC network. Then existing 50kW DCFC chargers are to be used with 60 kWh battery Bolt, which would need close to an hour for DCFC. This would make Bolt the slowest fast charging EV in the world. This is not good.<br />
<br />
For people who are looking to buy EV and only EV (no gas car) regardless of lack of
performance, Bolt will be very
good. Bolt will surely take market share away from Leaf, BMW
i3, eGolf that cost similar as Bolt with far less range.<br />
<br />
But for general public (mass market), Bolt isn't very good. With $30K, there are far better options. For example, Subaru WRX is quicker to 60 MPH AND it comes with AWD. Bolt falls way short.<br />
<br />
<a href="http://sparkev.blogspot.com/2016/01/mass-market-ev-to-bolt-or-not-to-bolt.html">http://sparkev.blogspot.com/2016/01/mass-market-ev-to-bolt-or-not-to-bolt.html</a><br />
<br />
Therefore, SparkEV is still the best, not only as EV, but as a car. We'll revisit this when Model 3 is released. In theory, Model 3 could have all the advantages of SparkEV (quicker than comparable cost gas cars, charge in 20 minutes or less) while also having 200 miles range.<br />
<br />
<a href="http://sparkev.blogspot.com/2016/01/mass-market-ev-hoping-for-tesla.html">http://sparkev.blogspot.com/2016/01/mass-market-ev-hoping-for-tesla.html</a>sparkevhttp://www.blogger.com/profile/04362518920979349841noreply@blogger.com1tag:blogger.com,1999:blog-6875771813122616391.post-41491186465841344512015-09-23T18:12:00.000-07:002015-11-26T11:01:40.503-08:00MPGe fraudThis issue has been bothering for a long time, even before I got an EV. In fact, I tried to establish true out of pocket cost MPGe pretty early in my blog. When gas cars list MPG, the consumer typically expects it to correlate to amount of money they pay to drive it with current $ per gallon at local gas station. With MPGe, it has very little to do with the amount of money one pays to drive the EV. When you use similar terminology that most people are familiar that relate to money and change the meaning completely to something else, that is fraud. It's like VW claiming their emission numbers were only meant for testing, but not for actual driving. Actual MPGe based on cost is described in the table in my previous blog.<br />
<br />
<a href="http://sparkev.blogspot.com/2015/05/spark-ev-miles-per-gallon-this-table.html">http://sparkev.blogspot.com/2015/05/spark-ev-miles-per-gallon-this-table.html</a><br />
<br />
I had long winded discussion in SparkEV forum to get to the bottom of this matter. What we found, with help from those in the forum, was that EPA uses "well to wheel" for MPG of gas cars while "tank to wheel" for EV. Simply put, MPGe assumes (somewhat correct under ideal conditions) that a gallon of gas has 33.7kWh of energy, and using that as a metric. For example, if a car uses 33.7 kWh of energy to drive 100 miles, that would be 100 MPGe. More popular example might be 16.85 kWh to drive 60 miles to yield 120 MPGe. Since SparkEV gets 119 MPGe EPA rating, this would be close to what SparkEV is doing.<br />
<br />
But this is problematic. How does one relate EPA MPGe to out of pocket cost to drive an EV? You can't. It is related to efficiency of the car, but that means little to most people; if it costs $1,000,000 to drive 1 mile while it's 99.99% efficient is meaningless. But costing $1 to drive 1,000,000 miles while it's 1% or 0.000001% efficient (maybe Mr. Fusion?) is meaningful.<br />
<br />
Far better number would've been miles/kWh (or kWh per 100 miles). But EPA being a bureaucratic nightmare government agency, they conducted a poll that showed miles/kWh "confused" the consumers when such metric was discussed. Instead, poll indicated MPG was better understood. Instead of applying MPGe in the sense that consumers understand (ie, $ to drive X miles) and can test for themselves, they applied it as completely nonsensical fashion. But since it relates to energy efficiency, EV drivers should be able to replicate EPA MPGe numbers at home, right? WRONG!<br />
<br />
I analyze various EV to see what I can find. Only fast charge capable cars are considered as I consider non fast charge EV as toys. Given the battery capacity and the range, the formula to compute EPA MPGe should be <br />
<br />
EPA MPGe = R / B * 33.7 * e<br />
<br />
where R is range in miles, B is battery capacity in kWh, 33.7 is kWh per gallon of gasoline, e is EV efficiency (must be less than 100%). As you can see from the table, it gives some radical numbers for efficiency, far more than 90% in many cases. Knowing that motors and controllers are 90% or less efficient, these are probably not true.<br />
<br />
<iframe height="300" src="https://docs.google.com/spreadsheets/d/15YV7zs0Cf5ucVvk-ddE3V2FHex6DA4dAJkI1WjpTZGM/pubhtml?gid=0&single=true&widget=true&headers=false&chrome=false" width="100%"></iframe>
<br />
An interesting observation is VW eGolf. The number is suspiciously close to EPA number. Did they actually test the car or did they simply take the range and battery capacity and do the math? It's VW, guys who faked EPA testing with the "clean" diesel, so questioning such conincidental number is warranted.<br />
<br />
Keen observer will note that modern EV do not use 100% of their battery capacity for stated range. Then how much do they use? This information is not readily available; it seems to be a "secret sauce" for many EV. For Volt, it was speculated to be about 50%, for SparkEV 80%, but the exact number is hard to come by. Without knowing this number, we can only guess, and I use 85% as guesstimate.<br />
<br />
<iframe height="300" src="https://docs.google.com/spreadsheets/d/15YV7zs0Cf5ucVvk-ddE3V2FHex6DA4dAJkI1WjpTZGM/pubhtml?gid=1191548221&single=true&widget=true&headers=false&chrome=false" width="100%"></iframe>
<br />
<br />
We seem to get more reasonable numbers, but there is a problem. SparkEV (119 MPGe) is only 71% efficient while VW eGolf (116 MPGe) is 85% efficient. Given that SparkEV has one of the highest head room, even more than Tesla, one would expect more air resistance by being taller (more frontal area) and may be lower efficiency than others. But to show VW eGolf to be more efficient than any other EV is questionable. Once again, remember the fraud VW committed with their "clean" diesel.<br />
<br />
Basically, what it shows is that without knowing the actual battery used for given range, one cannot replicate EPA MPGe number. Since actual battery capacity for range is not published, EPA MPGe is a meaningless number (it's a religion, not science). One may argue that this number can be used to compare one EV to another, but if cannot be replicated by the consumer, it's a dubious comparison at best.<br />
<br />
<b>mi/kWh to MPGe</b><br />
<br />
Here's another angle one can take. Take the EPA MPGe number and convert to mi/kWh.<br />
<br />
mi/kWh = MPGe / 33.7kWh/gal<br />
<br />
Then multiply that number by full battery capacity to figure out the range. Since not all battery is used, resulting range should be more than EPA range estimate. But that's not the case. If one uses EPA MPGe number, one gets far less range than the EPA estimated range (except eGolf). Inconsistency? You betcha!<br />
<br />
<iframe height="300" src="https://docs.google.com/spreadsheets/d/15YV7zs0Cf5ucVvk-ddE3V2FHex6DA4dAJkI1WjpTZGM/pubhtml?gid=1742395233&single=true&widget=true&headers=false&chrome=false" width="100%"></iframe>
<br />
Again, far better metric would be mi/kWh. But that number varies with different charging methods as shown in my previous blog posts (80% efficient with L1, 90%+ efficient for DCFC). But taking some conservative figure as described in my SparkEV efficiency blog post, SparkEV gets 4 mi/kWh. This is taking into consideration L1 charging loss (80% efficient), which is total energy from outlet to wheels not just energy from battery to wheels.<br />
<br />
<a href="http://sparkev.blogspot.com/2015/05/spark-ev-efficiency.html">http://sparkev.blogspot.com/2015/05/spark-ev-efficiency.html </a><br />
<br />
This corresponds to <br />
<br />
4 mi/kWh * 33.7kWh/gal = 134.8 MPGe <br />
<br />
If one considers battery to wheels per EPA, then the figure is 20% higher, or 161.76 MPGe.<br />
<br />
The real-world MPGe for SparkEV is far more than EPA MPGe even from "well to wheels". Then how the heck did EPA get 119 MPGe for SparkEV? Is it time to say "Who's John Galt?"<br />
<br />
<b>Honest MPGe</b><br />
<br />
To solve this confusion, better would be to qualify MPGe with various subscripts (or superscripts). For example, MPGe$ would correspond to equivalent $ to some particular $/gal of gas and $/kWh of energy. This is what the consumer is expecting to see with MPGe. It won't be a number, but a table like I show in my blog post. If it's a number, it must be qualified with $/gal AND $/kWh. For most consumers, this is the only MPGe that matters. Once again, here's the link to MPGe table.<br />
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<a href="http://sparkev.blogspot.com/2015/05/spark-ev-miles-per-gallon-this-table.html">http://sparkev.blogspot.com/2015/05/spark-ev-miles-per-gallon-this-table.html</a><br />
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Another would be MPGeEGG which would correspond to equivalent energy in gallon of gasoline. This is probably what EPA is getting, although it's impossible to compute at this time with given information. It's easy to remember, too; its a meaningless number of EGGheads.<br />
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Another would be MPGeEFF which would correspond to equivalent energy in fossil fuel used compared to gas car's gallon of gas use. Electricity for most parts come from fossil fuel, primarily natural gas and coal. Since electricity generation is far more efficient than gas cars, especially the combined cycle generators, one would need less fossil fuel to drive EV. This becomes especially important when non-fossil fuel is used to generate electricity. It's also easy to remember, EFF as in F as in we're fracked when we have to import oil. I will explore this in more detail in future blog post.<br />
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Another would be MPGeP which would correspond to equivalent in pollution compared to gas car's gallon of gas use. If coal is used for this calculation, EV would be worse (or awful if one considers coal ash). Radioactive pollution would be bad, too. This is more nebulous merit which must assign somewhat subjective weight to pollution from each source of energy. It may be discussed further in future blog post, but it'll be messy.<br />
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<b>Summary</b><br />
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In science, an experiment must be replicated by independent sources and reasonably close result obtained. Asking people to believe in something without such scrutiny is religion. As an EV advocate and science advocate, EV should not be a religion, although many people seem to treat it this way (ie, EV is NOT zero pollution, despite what Nissan Leaf prints on its doors). That means MPGe number must be something meaningful and derived from experiments from independent parties, not a number handed down by the EPA. I hope true out of pocket cost MPGe$ as table will be printed on windows of EV and educate the public rather than continuing with the religion that it is now.sparkevhttp://www.blogger.com/profile/04362518920979349841noreply@blogger.com0