Monday, December 7, 2015

SparkEV is quickest charging EV in the world

If 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.

http://insideevs.com/2016-30-kwh-nissan-leaf-sets-fastned-fast-charging-record/

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.

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.

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 12kW at 80% using 50kW charger. 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.

Then I encountered how slowly Leaf was charging. 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.

SparkEV charges faster than record breaking EV

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.

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.

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.


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.

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.

SparkEV is the quickest charging EV in the world!

Tesla Supercharging could take an hour

By now, it should be clear that I poke my nose into other EV business as evidenced by my MPGe$ for various EV post and Love letter to Leaf post. 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.

http://www.edmunds.com/tesla/model-s/2013/long-term-road-test/2013-tesla-model-s-how-quickly-does-a-supercharger-charge.html

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.

56kWh * (100%-17%) = 46kWh
46kWh / 90kW = 0.51 hours = 30.7 minutes

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?

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.


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.

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.

SparkEV is still the quickest charging EV in the world, even quicker than Tesla!

Tesla Supercharging power

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.

http://www.teslamotorsclub.com/showthread.php/23180-Finally-120KW-Supercharging!/page21http://www.teslamotorsclub.com/attachment.php?attachmentid=39704&d=1388704656

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.

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%.

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%.

SparkEV is still the quickest charging EV in the world, even at utilizing fast charger capacity!

Slow Tesla supercharging on same circuit

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.

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?

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.

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 ev-ranking blog post where I tweaked the parameter to favor Tesla.

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.

Conclusion

For a cheap "compliance car" 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.

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!

Edit 2015-12-15

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.

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.


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.

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.

http://insideevs.com/2016-30-kwh-nissan-leaf-fast-charging-record-21-03-kwh-26-5-minutes/

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.

http://www.evtec.ch/en/products/espressoandcharge/

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.

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!

Edit 2015-12-16

% 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.

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).

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.



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.

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.

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.

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.

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.

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.

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.

9 comments:

  1. The Spark EV is the quickest charging EV in the... wherever they have CCS chargers. My state has NONE. All the neighboring states have NONE.

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    1. CCS is being built out, so hopefully they will be in your area soon. If Chevy was smart, they'd installs CCS in all their dealers and price it as going rate similar to eVgo before Bolt is released to pull in competing EV drivers into their dealers.

      Bigger problem is that SparkEV is even less available than CCS. Still, for a cheap little car, it's impressive what Chevy engineers achieved. It's quicker than any car in % charged and coming within 10% to 20% of cars that cost 4 times as much (Tesla) in number of miles added per time.

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  2. ABB charger at BMW Group Plant, Oxford, UK, goes from 10 to 95% SOC in just 15 minutes on the i3 BEV. Beat that Tesla/Chevy SparkEV/Nissan Leaf et al

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    1. 10% to 95% = 85%. Assuming 100% on i3 is 20kWh out of 22kWh battery, 85%=17 kWh. To get that in 15 minutes, you need 68kW of power on average. ABB chargers only go to 50kW even at 100% efficiency (which it isn't). Considering charge taper requires even higher power from charger, I doubt what you claim is true. What I've seen is 30 minutes with i3 with ABB, so yeah, SparkEV easily beats i3.

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  3. You still have so many problems with your comparisons.

    SparkEV highway MPGe is 109. Using 157 MPGe is completely disingenuous. A Model S 90D gets 106 MPGe. Compare like situation to like situation.

    You screwed up the calcs for the 500 mile trip. First of all, each stop adds additional time just to make it to the charging station. Let's say both cars have full charge. We are going 500 miles. Each charging stop adds 4 miles and 10 minutes above charging itself. You then assume perfect spacing. Not real world, but ok. We use EPA highway MPGe, averaging 60 mph.

    You go 64 miles, then 2 miles to the charging station. Charge for 33 minutes. Then drive 2 + 62 + 2 miles, then charge for 33 minutes.

    500 66 minutes
    436 33 minutes charging, then 66 minutes = 99
    374 99
    312 99
    250 99
    188 99
    126 99
    64 99
    0

    total is 759 minutes or 12.65 hours. That's assuming perfect DCFC placement.

    A Tesla 90D starts with 290 miles of range, subsequent stops are 120 miles apart.
    500 290 minutes for 288 + 2 miles
    212 needs to add 40 kWh, so that's 25 minutes. Drive 124 miles, so 124 minutes = 149 minutes
    92 needs to add 31 kWh, so 18 minutes. Drive 92 miles, so 110 minutes
    0

    total is 549 minutes, or 9.15 hours.

    The Tesla can tolerate a lot of slop in that Supercharger placement and still get well under 10 hours.

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    1. As for "screw up" you mention, I explicitly say this: "While it's not apples to apples" and give scenarios for EPA MPGe as well as my experimental value. You should read it again.

      For 500 miles trip, yeah, that's not happening with SparkEV (or often), and that's not the point. The point of the comparison is that there is no question SparkEV is quicker than Tesla in terms of % charged. And if anyone thinks SparkEV is quicker in 500 miles trip than Tesla S, well, that's just delusional.

      However, SparkEV could be quicker than Tesla in terms of miles added per time on shared Supercharger (vs no-waiting case for SparkEV). Again, I explicitly state this in blog.

      As for time for DCFC, it's actually 20 minutes at the charger to 80%. If you sit at DCFC for 33 minutes, it would've reached 100% way before then. In contrast, Tesla to 80% would be over 45 minutes mainly due to taper.

      As for hypothetical long distance travel with SparkEV using DCFC, that's covered in another blog post. I have a graph of average speed including DCFC + time off/on highway + highway time that shows what is possible.

      http://sparkev.blogspot.com/2016/03/range-polynomial.html

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    2. By the way, I also state this:

      "Before you jump on "your table is ludicrous for making SparkEV faster than Tesla", read the explanations below."

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  4. If you do notice a vehicle winning the charging speed contests, question the variables underlying the physics trade off. What do I compromise by having a faster charge? Internal wear and tear, vs personal time waste.

    One thing Tesla and GM always bring up when questioned about charging speed, is that a faster charge is possible by sacrificing battery life and occupant safety. Charging a Lithium battery is not simple like filling a gas tank. (Gas by the way has a dozen variables on fueling speed too, vapor pressure, ingredients, etc) Each charge has slightly different variables. Get one variable wrong just once, the battery dies prematurely(Leaf) or the car catches fire(Volt/Tesla). Charging requires adaptive rates of volts & amps, altitude, air pressure/temperature/humidity, battery temperature, starting SoC, cell balancing, chemical decomposition over lifetime, etc. Tesla is open about it's compromises in charge speed to make the battery last 1 million miles. Tesla also uses historical data from all it's vehicles. Comparing similar variables from all cars and sending optimization updates to every car. I have not heard GM's position, but they appear to engineer vehicles to the more realistic 200,000 mile mark these days. GM also spends more time up front calculating the safe charge rates for the life of the vehicle. They may cautiously undershoot variables because they don't update like Tesla does. Nissan completely ignored the trade off with their first generation leaf, causing the whole world to think EV batteries were going to prematurely fail.

    Tesla owners who do not understand the complex calculations involved in just 1 extra minute of charging time, will definitely feel the spark cars are charging faster.

    ReplyDelete
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    1. If fast charging alone is the issue with battery longevity, we'd have lots of complaints with SparkEV owners with battery degradation. Fact is, it's not a problem.

      One should question what it means by "1 million miles battery". They don't mean zero degradation, but some finite amount. Also, Tesla battery is not drained to low on almost daily basis, unlike 80 miles range SparkEV. That makes direct comparison difficult, even if same number of DCFC are applied. Taking that into consideration, SparkEV does quite well.

      As for time taken, one only has to look at charge taper on Tesla to see that it's 40 minutes to 80%, double that of SparkEV. Knowing that Tesla battery overheats on extended driving at full speed (12+ minutes), I suspect the taper is due to inadequate battery cooling. With Tesla S aerodynamics only taking 14 HP (10 kW) at 70 MPH, 140 MPH would be 112 HP (80 kW), roughly that of supercharger power. Indeed, this is probably why Tesla tapers so quickly, the same reason why it cannot drive at top speed for long, which is inadequate battery cooling.

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