Capacity Loss on 2011-2012 LEAFs

[Stoaty]

This data is very interesting. It would be nice to see the data from the Leafs that lost two bars, plotted for the interval between the loss of the first and second bar. My limited data shows a 3%/month capacity loss and I believe I am about to lose my 2nd bar.

OK, by popular demand, here it is:



Relevant stats:

Second bar lost in 40-75 days after first bar lost. Mean time - 52.7 days, std dev - 9.7 days
Second bar lost in 800-3800 miles after first bar lost. Mean number of miles - 2095, std dev. - 864
Capacity loss per month ranged from 2.5% - 4.7%. Mean capacity loss per month - 3.7%, std dev. 0.6%

Miles/month vs. Capacity loss/month - correlation coefficient 0.10

Miles vs. Capacity loss/month - correlation coefficient 0.39 (I am not posting a graph because the correlation is in the wrong direction--the fewer miles you drive, the faster you lose capacity). This doesn't make sense, and the correlation coefficient is probably too low to consider there is much correlation.

[LEAFfan]

It looks like all of these cars are high mileage ones, ie. more than 15k a year.

I talked to some guy last night at a QC station who told me he just lost his second bar at around 9000 miles/1 year.

[Adrian]

Received an attorney advertisement in the mail today regarding Nissan Leaf battery problems. I leased, and as long as the car meets my needs I probably won't consider this option though I have to say loosing a bar at 24k miles in Orange County annoys me. I know I charge twice a day, but there is the example of the gentleman that is at 50k miles and charges twice a day and has not lost a bar yet. I know I said in my previous post I drive 80 MPH, but thinking about it, that's not really accurate. I drive 80 MPH when traffic allows, which is probably less than half the time during my morning and afternoon commute on the HOV lane. If anyone else is interested however, the website mentioned in the letter is http://www.nissanleafproblems.com" onclick="window.open(this.href);return false; and the email was leafbattery@initiativelegal.com . The firm is in LA.

[DarkDave]

Count me as another low-mileage 2 bars lost owner. I lost my 2nd bar last week at ~9950 miles. It was almost two months after loosing my 1st bar on 6/15. I've had my Leaf now for almost 18 months.

Interestingly enough, the drop in temperatures the past couple of days has allowed for an increase in charging capacity. This past Wednesday I only got 171 gid on an 80% nightly charge, and yesterday and today with the lower temps, I was able to get 181 and 182 gids.

[ALLWATZ]

High miles per month would also be generally indicative of those battery packs that tend to be cycled from very high to very low states of charge, and/or are heated, by frequent mid-day recharging, above those temperatures caused by ambient conditions.

So I think that the correlation of loss of capacity and cycling that you point out, could actually be, in part or in all, only coincidental.

Agreed. It could be higher depth of discharge, being left at high SOC for longer periods of time in order to do a longer commute, heating from mid-day recharging, etc. The main thing is that this is the first time I have found a correlation that suggests that calendar loss from high heat is not the only factor; something about the battery cycling seems to be involved also.

I'm not sure you can make that assumtion although I like the train of thought. All of the cars on the graph are cars experiencing high heat factors anyways, aren't they? I may be wrong but it seems the only way to factor out the heat, for uncorrupted data, is to have cycling data from cars in moderate climate areas to compare with those that we already have. Otherwise the data only shows that it is a spiral effect of high temps=capacity loss=cycling=capacity loss/miles.

[EricBayArea]

Received an attorney advertisement in the mail today ... http://www.nissanleafproblems.com" onclick="window.open(this.href);return false; ...

I hope to not lose a bar for many years, but if anyone does contact them they might want to point out their poor choice in wording:

...As a result, the vehicle may lose power more quickly and require more frequent charges...

Technically "power" is not being lost, "capacity" is being lost more quickly requiring more frequent charges. Power is what is warranted in the battery warranty, not capacity.

[Herm]

I know I said in my previous post I drive 80 MPH, but thinking about it, that's not really accurate.

Adrian, what is your lifetime efficiency with the Leaf?, that should describe how you drive.. but I think the important factors at this early loss is how long the battery remains at a high state of charge and at what temperature, not how you drive it.

[Stoaty]

Count me as another low-mileage 2 bars lost owner. I lost my 2nd bar last week at ~9950 miles. It was almost two months after loosing my 1st bar on 6/15. I've had my Leaf now for almost 18 months.

Looks like you are right on schedule (52.7 days average time between first and second bar loss). Sorry to hear it. Have you filed a case with Nissan? If not, recommend you do so. If you have, can you post the case number and date you filed for the Wiki?

Thanks.

[Adrian]

I know I said in my previous post I drive 80 MPH, but thinking about it, that's not really accurate.

Adrian, what is your lifetime efficiency with the Leaf?, that should describe how you drive.. but I think the important factors at this early loss is how long the battery remains at a high state of charge and at what temperature, not how you drive it.

According to Carwings, my 2011 and 2012 average energy economy is 4.5 miles/kwh. Not sure if this is the same thing as lifetime efficiency. If not, where do I find lifetime efficiency? I charge my car overnight inside my garage and always drive it the next day. So it does not stay at 100% charge more than 6 hours or so per night. I then charge it at work, which is outside, but really close to the ocean, so typically 10 degrees cooler than home. At work the car charges by noon and then stays charged until 5 or 6, sometimes later, when I drive home.

[LEAFfan]

Since the battery warranty DOES cover any capacity loss that isn't
"gradual", any intelligent person knows that a 15% or higher loss in about a year isn't gradual. So Nissan will have to fix these under their warranty. I really believe Nissan really knows this despite dealers being told to tell customers that this rate of loss is "normal."
So when it's posted that there is no battery capacity warranty, that's just not factual.