Tuesday, May 19, 2015

vs Nissan Leaf quick charge

Nissan Leaf gets special mention here, because that's the most popular EV on the market as of May 2015. There's lot to like, such as bigger and earlier to market (by 5 years). It also has the option of 6.6kW L2 charger compared to SparkEV's 3.3kW. If L2 is all there is, Leaf wins. But when it comes to quick charge, SparkEV does far better.

In previous post, I described SparkEV's DCFC with eVgo as roughly 0.01 kWh per second, up to 80% SoC. I took it all the way to 100% SoC, and the rate of charge does slow down after about 85%. At 90%, it's about 2 seconds per 0.01 kWh. At 99%, it's about 4 seconds per 0.01 kWh. It's not absolutely accurate, because time and kWh numbers were eye-balled, but it's pretty close.

There was Leaf owner charging next to me. I recorded the charging rate, and it slowed down very quickly. It started to slow down after less than a minute. It seemed to be slowing faster over time, but I only recorded two data points (this ain't Leaf blog!)

Starting: 30% SoC, 391V, 106A (41.4 kW or 0.011 kWh/sec)
7 minutes of charging later: 50% SoC, 394V, 51A (20 kW or 0.0056 kWh/sec)

Leaf's DCFC slows down to half as fast as SparkEV's rate. Is this Chademo vs CCS or Leaf's fan cooling vs SparkEV's liquid cooling or combination or? But the end result is that SparkEV kicks Leaf's butt in fast charging. This could have big implications when driving longer distances: can one drive over 1000 miles in a day with EV? Theoretically, SparkEV can barely do it, but not Leaf. No one can do that with So Cal traffic anyway, but it does make Leaf bit more of a hassle than SparkEV.

I suppose I could've taken multiple data points (video?) and do a plot of kWh vs time and find curve fit (linear? 1/t? e**-t?). But this is SparkEV blog, not Leaf blog. If Leaf owners want to find out how inferior their DCFC is compared to SparkEV, let them gather / analyze more data. I hope some do, because I am curious how much quantitatively suckier Leaf is compared to SparkEV.

Edit Oct 2015

Since Nissan started "no charge to charge" program where they give free 30 minutes of DCFC to Leaf owners, this has caused huge problem for public fast charging. Since it's free for 30 minutes regardless of car's state of charge, people would let the car sit there for 30 whole minutes whether they need it or not.

If 30 minutes actually deliver "FAST CHARGE", the car would be fully charged, and other people can charge their car. But in case of Leaf, charging slows down drastically as discussed above. How slow? I've seen couple of Leaf charging at almost 2kW (18 seconds for 0.01kWh) at 95% SoC. People were still hanging around and having other people wait when they could get faster charge from their L2!

I made some observations on few Leaf. It seems Leaf starts off at 41kW.

Then it begins to drop after about 4 minutes. At 4 min 30 sec, it's down to 100A, or 38kW. This was true only when SoC was low. When SoC was high (86%), it was far less than 18kW. Yes, there was someone trying to charge for 30 minutes when his car had almost 80% SoC already. Hey, it's free, let others wait!

This screen shot for 30 minutes is from another Leaf that I happened to see. I wasn't waiting around for 30 minutes to see how quickly Leaf drops. Yeah, it's not apples to apples, but you get the idea. At 95%, it was 10A, charging rate of less than 4 kW, even slower than L2! The Leaf driver would be saying "hey, why not? it's free for me, sucks to be you to be waiting"

If there's one thing that'll kill EV adoption, it's this kind of crap where you have to wait 2 hours to charge. What does it matter if it takes 20 minutes to get 80% when other people take 30 minutes each to charge, whether they need it or not. Nissan may have done well with EV by releasing the Leaf, but it is doing a fine job of killing EV with their crappy charging system and "no charge to charge" program.

Edit Oct 17, 2015

I ran into a Leaf driver who deliberately chose to use dual head charger instead of Chademo as she was pulling in. When I asked her politely to move her car we both can charge simultaneously, she said she didn't want to bother! Scroll down in link below to see what happened.


Below is a video of inconsiderate Leaf charging at 89% (she started at 76%!) at about 6 seconds for 0.01kWh (about 6 kW speed). Either Leaf drivers are unaware that fast charging is slower than L2, or they're simply evil people taking pleasure in making other people wait, even if they have a wait. I used to think it was the former (idiot Leaf drivers), but after this experience, I beginning think it's the latter.

Edit Oct. 18, 2015

There's an old saying about beating a dead horse. Actually, the only time to beat a horse is when it's dead. In that regard, here's another story about crappy Leaf fast charge. When I pulled up to this charger, Leaf was plugged in, but 30 minutes had expired. The driver, as usual with these no charge to charge Leaf drivers, was nowhere to be found. After all, why bother unplugging after you're done when it's free? They could take up the fast charge spot and prevent others from using it forever, and there's nothing eVgo can do to encourage them to get off the fast charger spot (eg, charge more money).

Nissan Leaf charging to 89% SoC

Leaf took 30 minutes to get to 89%, but only took 9kWh. On average, that's 18 kW. Assuming Leaf usable battery capacity is 22 kWh (probably less), 9kWh represents 40%. Since it stopped charging at 89%, we can guess that Leaf started charging at 50%. Well, at least the fast-charger-spot-taking-douche didn't start when he's at 80% and go away for hours like some other Leaf drivers.

I took SparkEV to 89% SoC, just like Leaf using the same charger to do some comparison.

SparkEV charging to 89% SoC

SparkEV took 20 minutes to deliver 13kWh, On average, that's 39kW, more than twice as quick as Leaf. In addition, I started with about 12% SoC (had 10 miles remaining), which means SparkEV added 77% in 20 minutes. Had I let SparkEV sit for entire 30 minutes, it would've reached beyond 100%.

Leaf doesn't have fast charging; they're simply made to take fast charge spot while slow charging! Thank you, no charge to charge for making all of us waste our time!


  1. Hey there, I own a Leaf, and while I don't have any nearby DCFCs to get good data, I did just complete a trip where I charged at one 50kW ABB DCFC unit and I filmed/timed/interval shot the charge. I haven't had a chance to plug it into Excel and do a best fit - but a preliminary look at the data shows that I started charging around 0.011kWh/s (or 40kW) from about 15 - 20%, it then slowed down to about 0.008 kWh/s from about 20 - 60%, then the taper became apparent at 75% to 88%, for the last 5% it was about 3 times longer for each % gained as when I was at 15% SOC. The charger kicked out after 30 minutes at 93% SOC. I didn't restart it.

    I do share your opinion on the "free charging" - TANSTAAFL (as my favourite author Heinlein wrote) - unfortunately humans just can't help themselves when something is free! Good intention, but the choice of delivery is incentivizing poor EV etiquette as you have found!

    1. What you show is bit different than few Leafs I've seen. If it's only 3 times slower at last 5% (88%+), then it would be charging at 13kW. I haven't seen such high rate in other Leaf, although that's based on only half a dozen observations.

      But if slowdown is heat related, it may matter when you charge. For example, if you just got off the road and plug in, does it slow down quicker compared to when you had to wait for another car? An interesting experiment might be plot of both scenarios, although thorough experiment would involve various ambient temperatures.

      When you have the plot posted, please share the link in the comments.

    2. Hello - I plotted the results of my charging session. You can access it here: http://kootenayevfamily.ca/?attachment_id=630

      I suspect I was charging in near ideal conditions. I would be interested to know the ambient temperature and battery temperature of the other Leaf's that you observed in the wild. I will log the data carefully from my next couple DCFC sessions... but since the closest station is over 300 km away, that may not be for several months unfortunately!

      You'll also notice that there isn't a best fit plotted - a second degree polynomial fit ok at 0.98 R2. I didn't bother to graph though.

      This was also my only DCFC session of the day, so multiple sessions in a row may not do nearly as well (since as you pointed out in your post, the Leaf relies on passive cooling and heat build-up in the battery is likely a concern after multiple DCFC session).


  2. Ambient tempeture on Leafs I've seen were typically 15-20 degreeC since I tend to DCFC at night after sun down. SparkEV has a bug where temperature is only displayed in C instead of F. The 2kW on Leaf using DCFC was observed at night probably 15 degreeC; I remember that incident well, because I had to wait for 3 Leafs with "No Charge to Charge" when I only needed 12 minutes to get to next charger. 3kW on Leaf DCFC observed during the day near 30 degreeC.

    Based on your plot, your Leaf seem to be doing extremely well, although I'm curious why % goes down from time to time. I'm also curious why your power seem to be piecewise steady while all the observation I saw were decreasing steadily over time.

    1. For anyone else wondering, I answered the same question in the comments to my attachment page at http://kootenayevfamily.ca/?attachment_id=630