Some Leaf Owners Experience Early Capacity Loss

[DaveinOlyWA]

I expect Leaf owners will experience the Tesla effect.. a leveling of battery degradation, mostly due to owners moderating their charge to 100% behavior. Assuming they find out about it.

At this rate some people will hit the 70% point sometime next year, a 3 year life for the battery will be disastrous publicity for Nissan. How will Nissan deal with it?.. will they ignore it?, was it smart for Nissan to include a battery degradation meter on the dash?

wow!! how did you extrapolate that conclusion?

the only thing i have concluded (with VERY limited information) is that its possible that heat quickens the degradation process to a degree greater than Nissan's anticipation

and the other is end user habits maybe a major factor as well. now, we do have a few reports of people who seem to have "followed all the rules" and are seeing degradation.

we have 6? or so here which means there is probably 6-15 out there that we either dont know about or they themselves have not noticed it yet.

but to say that anyone is on pace to have 30% loss by next year is simply counterproductive

 

[mkjayakumar]

Re: .-1, .-2

Until we find evidence of degradation on folks that follow the rule of "mostly 80% charging / if 100% drive within a few hours / don't let it sit at 100% on hot tarmac", I think we are blowing this out too much.

 

[Herm]

This is complete conjecture on your part with no basis for your extrapolation.

I used a very shiny crystal ball, so its not conjecture at all!

Are you going to answer my 3 questions?

 

[Herm]

we have 6? or so here which means there is probably 6-15 out there that we either dont know about or they themselves have not noticed it yet.
but to say that anyone is on pace to have 30% loss by next year is simply counterproductive

You think most Leaf owners follow this forum?.. perhaps they do, I dont know.

If some people have lost a bar in the first year, perhaps they will lose a second bar in the second year.. assuming the second bar is also 15% then that adds up to 70% remaining capacity.. that is considered a worn out battery.

Lets hope these cases were bad batteries from the factory.

 

[DaveinOlyWA]

we have 6? or so here which means there is probably 6-15 out there that we either dont know about or they themselves have not noticed it yet.
but to say that anyone is on pace to have 30% loss by next year is simply counterproductive

You think most Leaf owners follow this forum?.. perhaps they do, I dont know.

If some people have lost a bar in the first year, perhaps they will lose a second bar in the second year.. assuming the second bar is also 15% then that adds up to 70% remaining capacity.. that is considered a worn out battery.

Lets hope these cases were bad batteries from the factory.

actually my numbers suggest that only about a third or fourth are here and that some of the ones here may have suffered loss but are unaware of it.

now i can say for myself; i drove EVs for 3½ years before my Leaf arrived and it was simply battery management Hell dealing with lead acid issues, so i pretty much knew what i should or should not do.

its now 16 months and 16,000 miles later and i have no range degradation but have not topped off much (sure i have done a partial charge at night then topped off in the morning for a busy day of driving) and the car has only twice sat at 100% longer than 8 hours (once for 36 hours!!...oh well, whose perfect?)

so why is that?

1) being one of the first maybe Nissan took extra care to give me a good pack?
2) being in a cooler climate helped
3) having "better" battery management skills
4) driving in eco with minimal use of regen
5) just dumb luck

i think in all of this;

1) we have incomplete information
2) we have not fully assessed the effect of the user's charging habits
3) unlike most here, i believe the way you drive the car does not matter. jackrabbit starts, etc probably dont hurt.
4) and yes, i also agree that MNL does not really give us a full picture here. what we know could also be much larger than the general population. we cannot extrapolate the 6 or 7 we know about and assume that percentage will be constant thru out the country especially when most are in extreme climates and most of us dont live in extreme climates.

 

[palmermd]

You think most Leaf owners follow this forum?.. perhaps they do, I dont know.

actually my numbers suggest that only about a third or fourth are here and that some of the ones here may have suffered loss but are unaware of it.

There are a little over 5000 members listed here, and a bunch of those are spammers who registered. If they were all leaf owners we would have at best 50% representation, so your estimate of 25% representation is probably close to what I would guestimate as well, perhaps not even that high.

I agree that we are getting a little overly concerned about this. It is something we should continue to track, but its a bit to early to jump to any conclusions.

 

[davewill]

why cant you just have timer 2 set daily from 7pm to 8pm and timer 1 set daily from 5:30am to 7am. Timer 2 only has to be a rough estimate to get you near 50% and timer 1 needs to be long enough to get you from the lowest timer 2 would get to from zero to reach full.

I thought that each day can only have one timer set. If that is wrong, so much the better. I will check on it.

Not wrong, you are absolutely right. One timer per day.

 

[LEAFfan]

Just remembered, early on a Roadster owner told me to expect the biggest loss in the first year or so, somewhere around 5-10% and that it would level out and be more gradual from then on, that is what was common for Roadsters. can any Tesla owners verify this?

That's almost verbatim what the Nissan tech was told by Nissan to tell me. So even though we have a different chemistry and type battery than Tesla, maybe it acts the same as far as capacity loss goes. I'm around 10-12% loss with just a few weeks shy of one year and a little over 9K miles.

 

[GaslessInSeattle]

Maybe what you guys in Phoenix are seeing is simply the first phase of natural aging, just accelerated. If it levels out then no biggy because in reality we are all headed there at some point in the initial years of ownership. I suspect there are things that we all can do to slow that down, but that eventually we'll all see that drop (and hopefully a leveling to follow).

I've realized that most days we only use a few bars, so I'm cycling the charging within a few bars of the 6th bar (roughly 50%) rather than plugging in and charging to 80% all the time. my understanding is that 50% is roughly chemical equilibrium, reducing or nearly eliminating cladding of the cathode/anode. heat simply accelerates the effect of time, so the further you are from 50%, the greater the multiplier of heat and time is. true 50% is probably more like 4 bars, since there is a hidden bar and the BMS reserves some out of reach at the bottom. the effect of SOC and heat/time on battery life is probably more like exponential or logarythmic in relation to the distance from 50% so it's mostly the extremes that are worth really going out of your way to limiting. It sounds like Nissan has taken care of most of the issue on the low end by keeping the true bottom of the battery out of reach. Worrying about where exactly 50% is is probably splitting hairs as anything within the middle 4-8 bars is still pretty much ideal for night and daytime idle periods (I think of this as the green zone) with bars 2+3 and 9+10 being close to ideal (yellow zone) and 1+2 and 11+12 (red zone) worth avoiding for prolonged periods.

Bottom line, I'm mostly just not plugging in the car every chance I get like I used to and only charging up to 80 or 100% close to when I need it. For those with a long commute, simply using an end timer does the trick, keeping SOC down for the overnight and since they likely arrive at work close to 50%, the day time idle period is covered. In AZ, it would seem that simply avoiding leaving the car at a high SOC and high temp for prolonged periods is more critical than in cooler climates. Hopefully we will have solid data on this at some point and won't have to guess where the thresholds are... until then, I'm leaning in a more conservative direction as are result of these cases. A QC network will allow us all to relax a bit on our daily charging habits as keeping the car at a lower SOC will have less of a limiting effect on readiness for unexpected travel, and of course a much larger battery will allow moderating SOC much more convenient.

Just remembered, early on a Roadster owner told me to expect the biggest loss in the first year or so, somewhere around 5-10% and that it would level out and be more gradual from then on, that is what was common for Roadsters. can any Tesla owners verify this?

That's almost verbatim what the Nissan tech was told by Nissan to tell me. So even though we have a different chemistry and type battery than Tesla, maybe it acts the same as far as capacity loss goes. I'm around 10-12% loss with just a few weeks shy of one year and a little over 9K miles.

 

[TRONZ]

A QC network will allow us all to relax a bit on our daily charging habits as keeping the car at a lower SOC will have less of a limiting effect on readiness for unexpected travel

Yes. I would say I charge to 100% typically for this (readyness) reason. Most days of the week we come home with 4-6 bars but every now and then each week we roll into the garage with only 1-2 bars. These depletion events seem to not happen regularly so I can't isolate my opportunities to only do 80% charging. I also drive with a 3.3 average and live in a hilly stop and go region behind Laguna Beach. For example, I drove a few quick errands this morning that covered 16 miles. From 100% I just snuffed out the 4th bar down as I pulled into the garage. Not sure if killing 4 bars in 16 miles (4 miles per bar) is average after 16,000 miles but could be a bit of capacity loss showing up. I should probably start to pay more attention to the numbers as we get toward the backside of our lease.

 

[Herm]

Most days of the week we come home with 4-6 bars but every now and then each week we roll into the garage with only 1-2 bars.

Do you think this would change if you had a higher capacity battery ?

 

[TRONZ]

Most days of the week we come home with 4-6 bars but every now and then each week we roll into the garage with only 1-2 bars.

Do you think this would change if you had a higher capacity battery ?

Well I would probably be inclined to charge to 80% regularly if I did not end up in the last 2 red bars on occasion. On those days I am thankful I started at 100%. If I never seemed to use more than 50% of capacity each day on a larger pack I would surely be in the 80% club.

I guess I also have never really modified my driving behavior because I am driving an EV. I just drive how I want, run the AC how I want and don't really stress about it. I know some people are really interested in data but I have been on Carwings a total of two times. It is an interesting question though, if I had more capacity would I find a way to use it? Probably.

 

[GaslessInSeattle]

Let's hope Nissan doesn't play a double standard with owners vs leasers, telling owners that 15% loss a year is gradual and not covered while making a big deal about it to Leas holders and sticking the cost of battery replacement on them at the end of the Lease if you haven't stuck to MRF recommendations.

A QC network will allow us all to relax a bit on our daily charging habits as keeping the car at a lower SOC will have less of a limiting effect on readiness for unexpected travel

Yes. I would say I charge to 100% typically for this (readyness) reason. Most days of the week we come home with 4-6 bars but every now and then each week we roll into the garage with only 1-2 bars. These depletion events seem to not happen regularly so I can't isolate my opportunities to only do 80% charging. I also drive with a 3.3 average and live in a hilly stop and go region behind Laguna Beach. For example, I drove a few quick errands this morning that covered 16 miles. From 100% I just snuffed out the 4th bar down as I pulled into the garage. Not sure if killing 4 bars in 16 miles (4 miles per bar) is average after 16,000 miles but could be a bit of capacity loss showing up. I should probably start to pay more attention to the numbers as we get toward the backside of our lease.

 

[TRONZ]

Well, I'm not sure if you can play this hand if you can't even see what cards your holding. I am fine with some capacity loss as its to be expected. But getting handed a piece of paper with black boxes filled in is not going to cut it either. As far as I can tell the most technically savvy on MNL are not even sure of the usable capacity in a LEAF. Nissan should be providing guidance here but is also trying to protect very valuable data from competitors. It will probably just come down to "Is the car working for you" at the end of three years?

 

[SanDust]

How many people still think a thermal management system for the battery pack is unnecessary?

 

[Smidge204]

How many people still think a thermal management system for the battery pack is unnecessary?

Until it's actually proven that temperature is the cause, or even a major contributing factor, there is no reason to think thermal management would have prevented the problem. Jury is still out.
=Smidge=

 

[vegastar]

For me it is unnecessary and I prefer to avoid the added price and complexity of it. But there are some places where it could be necessary. The loss of capacity cases we have show that probably high temperatures assotiated with high average SOC do affect the gradual capacity loss in a strong way.

 

[RegGuheert]

How many people still think a thermal management system for the battery pack is unnecessary?

I think it is unnecessary where I live, for my application. It remains to be seen if it would make a significant difference in Phoenix or not.

At the end of the day, I think the answer will be the lifecycle costs will be lower without it in some applications and higher without it in others. In the future, that may determine which EVs sell into which markets.

I'm afraid that Nissan and the LEAF may take a well-deserved beating because of poor battery capacity life in Phoenix and similar markets. We are just seeing the beginning...

 

[TRONZ]

I think Volts have been a lot more inclined to have "thermal events" than LEAFs but that's a different topic. I actually keep thinking my battery temp gauge is broken because it never moves. However it is a fair question to ask if any LEAFs are unduly suffering in the deserts. I don't think anyone imagines Nissan would design a global car catering to outliers, but it doesnt mean they should be flatly disregarded as flukes either. The real issue is correctly vetting information and data from LEAF owners. Lots of noise from non owners trying to poison the well makes it even more difficult to hear what's really going on.

 

[Herm]

I really dont want a liquid cooling system in my battery vs the metallic heat conduction system that Nissan uses.. but perhaps a forced air system like Coda and Mitsubishi use would work ok.

If it turns out there are issues in Arizona there are things that Nissan could do..

1. car defaults to 80% charge automatically, you have to push a button to enable a charge to 100%.. like Tesla does with the Roadster.

2. automatic self-discharge if the car has been parked at 100% for over 6 hours (run the AC or heater) with better remote control system for people that park long term at the airport.

3. an educational video on a DVD, or in the car's info system.. to explain things to the customer.