jsantala
Posts: 296
Joined: Fri Sep 12, 2014 9:32 pm
Location: Finland
Contact: Website

Battery degradation

Fri Sep 12, 2014 9:47 pm

I'm planning to purchase a 2011 Citroën C-Zero, the Citroën's variant of i-MiEV. It's been their floor model which they haven't been able to sell in three years, possibly due to the 35.000€ price tag. Don't worry, I'll get it for less than half of that. I don't know the miles on it yet, but I'm guessing they're very low and the car probably has been inside in warm storage for the most part.

So the question is, what kind of battery degradation have you observed in your own iMiEVs over the years and miles driven? I'm only interested in actual user reports, not hearsay or guesswork. How far can you go with your pack now compared to new?
kWsaki.com / EVs: Nissan Leaf 2012, Citroën Xsara 1997 (conv. 81V & 8" Series DC) and Kawasaki GPX750R 1987 (conv. 87V & ME1003 PMDC) / Used to have a Citroën C-Zero 2011

Malm
Posts: 449
Joined: Mon Jul 22, 2013 12:16 pm
Location: Tábua - Portugal

Re: Battery degradation

Sat Sep 13, 2014 3:15 pm

I have an i-MiEV since april 2011. I'm from Portugal. The worst enemy of electric cars is the high temperatures, and the Nissan Leaf from Arizona showed that fast. My country is not so hot, but have high temperatures (more then 30º C) often in summer.

Most users with 2011 and 2012 will not see any difference. They will do now the same mileage (or very little difference) that they did two or three years ago. But that doesn't mean 0 degradation. That degradation maybe only can be found at very low SoC, and most of us avoid to take the car bellow 20% SoC.

In mine, there is clearly a difference between 2011 and 2014. Not easy to get the correct number, but I fill I lost between 10 to 15% of original capacity.

In Finland, because the high temperatures are not a problem, lost of capacity will not exceed 1 to 2%, I think.

If you want to know more of what an i-MiEV can do, you can watch some of my videos:

https://www.youtube.com/channel/UCtO0sV ... a37X3XsNbw
Riding an i-Miev since 4/2011 in Portugal, 100.000 kms.

jsantala
Posts: 296
Joined: Fri Sep 12, 2014 9:32 pm
Location: Finland
Contact: Website

Re: Battery degradation

Sat Sep 13, 2014 10:45 pm

Thanks for your reply, Maim. It's good to hear that the battery degradation in the i-MiEV and it's variants doesn't seem to be as bad as on the Leafs. I figured as much, since I haven't heard anyone complaining about it.

Heat is an issue, but as you said, it's not an issue around these parts. Last summer we got temperatures of over 30 degrees Celsius, but it's certainly not the norm here. Then again, who knows, the climate change seems to increase extreme weather phenomenon.

The real problem here is the cold. Lithium batteries don't particularly like to charge while frozen either. Remains to be seem what kind of a problem that ends up being, but I will try to figure out a way to heat my batteries, if at all possible. More on that on the Battery air intake post.
kWsaki.com / EVs: Nissan Leaf 2012, Citroën Xsara 1997 (conv. 81V & 8" Series DC) and Kawasaki GPX750R 1987 (conv. 87V & ME1003 PMDC) / Used to have a Citroën C-Zero 2011

Don
Site Moderator
Posts: 2997
Joined: Thu May 10, 2012 3:55 pm
Location: Biloxi MS

Re: Battery degradation

Sun Sep 14, 2014 8:16 am

I *think* our battery degradation is hidden 'below the turtle' - In other words, in a brand new car when you see the turtle, you can drive another 15 Km or so before the car slows to a crawl. In a car with 30,000 Km's on it, that number might be reduced to 6 or 8 Km's and after another 30,000 Km's it may be reduced to none at all - The turtle shows and the car quits shortly afterward

So, what the user sees for the first few years is . . . . no degradation at all - The car still goes as far as it ever did before the turtle shows up and the RR numbers after a full recharge remain about the same, but . . . . the battery *is* ageing and it actually *is* losing a percentage of it's capacity - We just don't see it

That's my theory anyway

Don
2012 iMiEV SE Premium, White
2012 iMiEV SE Premium, Raspberry Metallic
2012 iMiEV SE, White
2017 Chevy Volt Premier
2014 Ford Transit Connect XLT SWB wagon
2006 Itasca Navion Sprinter Motor Home

jsantala
Posts: 296
Joined: Fri Sep 12, 2014 9:32 pm
Location: Finland
Contact: Website

Re: Battery degradation

Sun Sep 14, 2014 9:40 am

Don, is that just theory or actual first hand experience?
kWsaki.com / EVs: Nissan Leaf 2012, Citroën Xsara 1997 (conv. 81V & 8" Series DC) and Kawasaki GPX750R 1987 (conv. 87V & ME1003 PMDC) / Used to have a Citroën C-Zero 2011

JoeS
Site Moderator
Posts: 3937
Joined: Thu Dec 15, 2011 5:47 am
Location: Silicon Valley, California

Re: Battery degradation

Sun Sep 14, 2014 10:36 am

jsantala wrote:Don, is that just theory or actual first hand experience?
jsantala, I happen to agree with Don's theory, but the problem is that few of us are willing to take our cars down to turtle to test this theory. The closest to doing this is Malm, and you might peruse his posts to try to figure out what he's saying about this. In practice, I have over 32,000 miles (51.500km) on my USA (16kWh) i-MiEV and have yet to see any noticeable battery degradation (except for a stepped range decrease when I switched to non-OEM tires). As far as I'm concerned, battery degradation is a non-issue in the i-MiEV, but I do treat it properly in the hopes that it will serve us for well over 100,000 miles.
EVs: 2 Wht/Blu SE Prem., '13 Tesla MS85, 3 156v CorbinSparrows (2 Li-ion), 24v EcoScoot(LiFePO4)
EV Conv: 156v '86 Ram PU, 144v '65 Saab 96
Hybrids: 48v1kW bike
ICE: '88 Isuzu Trooper. Mothballed: '67 Saab (orig.owner), '76 MBZ L206D RHD RV

PV1
Site Moderator
Posts: 3078
Joined: Fri Apr 27, 2012 4:22 pm
Location: Pittsburgh, PA
Contact: Website

Re: Battery degradation

Sun Sep 14, 2014 7:14 pm

I'm just over 15,000 miles and pushed my car down to 8% yesterday (personal record low and well into turtle range), and my cells were holding 3.5 volts under a 25 kW load (half power). Even on the low end, my cells are pretty well balanced, with about a .1 volt stray at the worst. The car has the turtle reserve, and then the cells aren't even empty after the car reaches 0%. The portion between car 0% and battery 0% is where the hidden degradation is, which explains why Malm's car recalculated its capacity after 3 years of driving. His battery degraded to the point where it would hit low-voltage cutout while within the usable state of charge range. It recalculated to put low-voltage cutout back outside of the usable range. Now his car shuts down before the cells hit LVC.

My theory, of course.
"Bear" - 2012 Diamond White Pearl ES with QC
"Koorz" - 2012 Cool Silver Metallic ES with QC
"Photon" - 2017 Bolt EV LT in Orange with QC
Solar-powered since 10/10/2013

Life with Electric Vehicles: https://lbry.tv/@PV1

jsantala
Posts: 296
Joined: Fri Sep 12, 2014 9:32 pm
Location: Finland
Contact: Website

Re: Battery degradation

Mon Sep 15, 2014 3:34 am

If the cells in the iMiEVs are anything like the LiFePO4 cells (which they are not), then the capacity below the "knee" of the voltage drop is minimal. Once that voltage start dropping faster there's hardly any juice left. Again, at least on the LiFePO4 I've used to with my DIY projects. I've build a motorcycle with 40Ah cells and my car now has 60Ah cells. They just don't have quick charge which I'd need for longer trips. Unless I pack my car full of 400Ah cells, of course. ;)
kWsaki.com / EVs: Nissan Leaf 2012, Citroën Xsara 1997 (conv. 81V & 8" Series DC) and Kawasaki GPX750R 1987 (conv. 87V & ME1003 PMDC) / Used to have a Citroën C-Zero 2011

mixmike6
Posts: 47
Joined: Wed Aug 06, 2014 9:56 am
Location: Montreal, QC

Re: Battery degradation

Mon Sep 15, 2014 6:48 am

As far as I can tell it seems to be pretty plastic-ee under there.

Here in the wintertime the temps also get pretty low in the -20s and -30s. I read on one post that leaving the pack charging using the level 1 charger at 8amps would be a good idea to keep the battery when the car is parked outside.
Mike D.
2014 Ocean Blue i-MiEV ES
Montréal, QC

danpatgal
Posts: 202
Joined: Mon Feb 27, 2012 10:21 am
Location: Ephrata, PA

Re: Battery degradation

Mon Sep 15, 2014 7:40 am

We've not noticed battery degradation in almost 20,000 miles. But, just two other comments on your potential purchase:

I'd have no hesitation buying the car in cold climates if I could at least park it in a garage overnight. It makes a lot of difference to have at least 10 to 20 C degree buffer over the outside cold (we got down to -15C a few times this past winter). The few times we had the car parked outside for an extended period cold soaking, it was hard to get the cabin to a bearable temperature (not warm, just bearable) and we took a pretty good range hit in those instances. Hopefully this winter won't be as bad (I guess Finland has winters like this all the time, but maybe that's just a common misconception.)

Regarding the % SOC theories and lithium, I can tell you I did experience that "cliff" once in my EV conversion. It was stupidly dramatic. Going kind of fine one moment, then - bamn, got to pull over and embarrassingly plead for charge the next. I think Mitsubishi must account for that "knee" much better than I can with my basic BMS/SOC information.

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