Capacity Loss on 2011-2012 LEAFs

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I have pondered this too, wondering if that design wouldn't backfire. hmm, yet another question for the wiki: frequency of using pre cooling at 100% SOC. I saw this mostly with prewarming on my first leaf. It appeared that prewarming after a 100% charge would allow the battery to get overcharged some, resulting in greater range, though I didn't have a gid meter to verify. I started timing the prewarming from a 80% charge and did a variety of experiments prewarming from 80% to 100% charge to attempt to raise the core temp of the battery in cold weather. while I did not want to overcharge the battery, I did find that prewarming for extended periods, from 80% SOC would warm the battery some and return some of the lost cold weather range.

If I lived in Phoenix or other areas with extreme heat, I'd do some experimenting with precooling from 80% or lower for extended periods and see if you can lower the temp of the battery or at least keep it from getting so high (wish we had the Leafscan to actually see the battery temp!). the car would of course have to be kept plugged in. conversely, I'd avoid precooling from a 100% charge in hot climates, as I am quite sure this allows for the battery to take on some excess voltage. super high heat and extra high SOC would likely compound the rate of degredation.

Pipcecil said:
I am curious as well why our gauges are 5% off, respecitively ~5% lower for each and every car. This could be the "software" bug that has been floating around on this thread. Regardless, that still doesn't address the accelerated loss occuring (it may not be as extreme but it is still significant). I am extremely afraid Nissan is counting the ~7% of our battery that cannot be accessed. To me, its very misleading to include that total since we would never be allowed to use it! But thats only speculation, and we can't verify that at all.

I do know that since I have owned the car, I am experiencing ~15-20 miles reduced capacity from new. That is with improved driving habits (finally hit 4 mi/kWh last month for lifetime average!), a very mild north Texas summer, and more chances to pre-cool/heat to extend my range. If I had retained the same level, I would be getting more range now. If I had lost only a few %, I think I would be having the same range with better "oustide" factors.

An interesting idea that occured that could relate to quicker degredation is "topping off" I am not aluding to plugging in the car to charge if 80% or greater capacity remains (something the manual advises to mimimize), but the use of the heating and cooling, especially on a 100% charged car. Everyone here knows that instead of creating a dedicated circuit to handle power from the outside source to run the A/C or heater, the LEAF uses the default set-up and pulls energy from the battery itself while the outside line recharges the battery. I recognize this when I precool my car in the morning for about 25 minutes with a the Level 1 (my wife uses the Level 2 for the volt). I am actually down some power (my time to charge will range from 10-40 minutes via Level 2 on the dash), once I was even down an addition fuel bar when I leave. If "topping off" is not ideal, why have this setup with easy access to climate control your car and encourage it to extend range!

It could be a compounded problem as the heat + the topping off occuring from using the CC together causes extra degradation? Its only a guess. If this was a greater factor than the heat (I doubt it) a proof of concept would be vehicles in extreme cold climates seeing battery loss from this next winter (cars would be a year+ by then too). If the idea does not hold clout then they will all drive happily to and from work!
 
Scott Yarosh, (down to nine capacity bars), told me yesterday he did a 100% charge, drove 28 miles, and returned home with only two SOC bars remaining. Not a viable vehicle anymore.

My dealer called me this morning and said he was in touch with "Nissan engineers". He was told they were looking into the problem. At least they referred to it as 'a problem' and not a normal phenomenon.
 
myleaf said:
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: ;)

capacitylossfirsttoseco.jpg


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.
 
OrientExpress said:
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.
 
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 [email protected] . The firm is in LA.
 
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.
 
Stoaty said:
edatoakrun said:
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.
 
Adrian said:
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:

Nissan LEAF problems website said:
...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.
 
Adrian said:
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.
 
DarkDave said:
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.
 
Herm said:
Adrian said:
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.
 
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.
 
Stoaty said:
Here is the same data from the Phoenix area one bar losers presented in a slightly different way that drives home the point that racking up miles more quickly leads to quicker loss of battery capacity. I have plotted Miles Driven Per Month vs. Percent capacity loss per month. Linear regression shows:

slope - 831
intercept - 168
correlation coefficient is 0.51 (moderate correlation)

Since miles driven per month means more cycling of the pack per month, it appears that both heat and cycling of the pack are factors in capacity loss

Not just number of cycles, but higher mileage rates might also correlate to deeper average discharges and a higher ratio of 100% charges.
 
Boomer23 said:
Nekota said:
file.php


edit with link to battery with pink (I think airflow?)

https://docs.google.com/open?id=0B-80HTqdiCI3enh1LXRKNFdPWkE" onclick="window.open(this.href);return false;
Is there text that says that the pink is air flow?
Here is what appears to be an English-language version of the same document. The pink colored area seems to be structural support.

batterypackenclosure
1
 
Stoaty said:
...
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.

perhaps the low mileage cars sit at a higher SOC and it would make sense that since ambient temp is fairly constant across the group, the high SOC + high temp accelerates decline faster than those who charge up to go to a longer distance to work and arrive at a Low SOC for the hottest part of the day, or some other similar scenario.
 
Nubo said:
Not just number of cycles, but higher mileage rates might also correlate to deeper average discharges and a higher ratio of 100% charges.
Awesome data, great work! For what it's worth, last time I looked, the small sample I was evaluating suggested that little more than half of the capacity loss depends on the climate at the place of residence, and the rest is split roughly equally between mileage and vehicle age. The latter seemed to be more significant, but it's tough to say from a small sample. I could be wrong, but I'm under the impression that you are essentially removing the climatic effect by evaluating only cars from (roughly) the same locale.
 
GaslessInSeattle said:
perhaps the low mileage cars sit at a higher SOC and it would make sense that since ambient temp is fairly constant across the group, the high SOC + high temp accelerates decline faster than those who charge up to go to a longer distance to work and arrive at a Low SOC for the hottest part of the day, or some other similar scenario.
That is an excellent thought. We really need a lot more detailed info about charging patterns, average SOC, time spent at high SOC (> 80%), etc. Hard to get that data for the Wiki.
 
I will fill that out,but if they contact me back,I will indicate Im still waiting on Mr.Perrys final decision do next month..
Adrian said:
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 [email protected] . The firm is in LA.
 
Just received a PM reporting loss of 3 capacity bars from a new member, gk1. Here is his report:

"I lost my third capacity bar on my LEAF a few days ago and throught this might be interesting information to add to your list.

I lost the first bar at 3500 miles after just 3.5 month (End of June to Beginning of October - so all through summer)
I lost the second at 10500 miles after 12 month (just before the yearly battery check or just at the start of the next summer)
I lost my third capacity bar at Aug 14, 12000miles, Chandler, AZ, 12000 miles, owned: 14 months (just after we hit 118F)

I reported the first one immediately and they had the car for a cople of days and told me afterwards that this is "normal". I didn't get a case number for this, but I still have the initial email response, the battery report and the phone number of the engineer."

His VIN is listed as 05080. Leaf delivered June 27, 2011
 
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