Capacity Loss on 2011-2012 LEAFs

[nogajim]

I think there must be a combination of effects going on: a moderate permanent loss of capacity on top of a seasonal loss from temperature. The timing of people losing bars at nearly the same time at the same place would fit with a seasonal effect. And since virtually no one had any sort of capacity measurement meter this time last year, we can't sort out how much comes from each. I would bet that some people who lose a bar this summer will get it back.

 

[vegastar]

I've got some more bad news - my 100% charge last night only got me 79.0/222 Gids. Though, strangely, still @ 393v. I am on the cusp of this being unacceptable. UNLESS, I suppose, I'm taking the entire 20% loss expected "over 8-10 years" NOW and there won't be any further loss. :?

Edit: Never mind the 393v comment...I just read Tom's post about the 100% and 80% voltages being fixed. That sorta explains it.

Did you lose a capacity bar?

Do you notice a acceleration of the degradation lately? I think your previous 100% gid readings were well above 222 gids, right?

 

[mwalsh]

Did you lose a capacity bar?

Do you notice a acceleration of the degradation lately? I think your previous 100% gid readings were well above 222 gids, right?

No capacity bar loss yet. Apparent massive acceleration in charge level degradation over last 6 weeks. Almost scarily so! :shock:

 

[DaveEV]

I believe we can check for the unbalanced condition by monitoring the total pack voltage at the 100% charge condition. According to my model, if the pack is balanced at 100% charge, all the cell-pairs will have the maximum allowed voltage, and the total pack voltage displayed by the SOC meter will also be at a fixed maximum that should be the same for everyone. Conversely, the pack will be out-of-balance if and only if the pack total voltage is less than this maximum, because some of the cell-pairs are not at their maximum values.

At my 100% test, the pack voltage was either 394.0V or 394.5V.
My 80% charge point is 387.5V. I would be interested in how these values compare to other folks' voltages.

Yes, this is why I've encouraged people to record pack voltages with their charge. One note about 80% voltages, though - until we're able to read cell-level voltages, there's 3 possible triggers the car can use to stop charging: 1. Min cell voltage - stop charging when the lowest cell reaches 80%. 2. Max cell voltage - stop charging when the highest cell reaches 80%. 3. Avg cell voltage - stop charging when the average cell voltage reaches 80% (aka when entire pack voltage reaches 80%).

Getting more pack voltage data from 80%/100% charges will help determine which of the 3. Recording ambient temperature at the time of the reading is also a good idea given that GID readings appear to inversely correlate with temperature.

I think there must be a combination of effects going on: a moderate permanent loss of capacity on top of a seasonal loss from temperature. The timing of people losing bars at nearly the same time at the same place would fit with a seasonal effect. And since virtually no one had any sort of capacity measurement meter this time last year, we can't sort out how much comes from each.

It sure seems strange that all of a sudden many cars are showing a rapid loss in GID counts. Many people with low readings today were showing significantly higher readings as little as a couple months ago.

There definitely seems to be some sort of inverse correlation with temperature and GID count...

 

[JPWhite]

My loss in 9 months for 80% charging is 3/224 = 1.34%. I doubt I could do any better than that, but will see when I next charge to 100%. I will report Gids and pack voltage at that time.

It's good to see a positive report amongst a sea of negative ones. Thanks for sharing.

Extrapolating from your figures (dangerous activity at best) you should be on target for 1.8% annual capacity loss. Which would mean you won't see the first capacity bar disappear until 2020 Comparing LA average temps to Nashville average temps I am encouraged that my results may be similar, all things being equal.

Can't wait for Phil to come out with LeafScan so we can know the actual battery pack temperature and plot degradation over time. I too wish Nissan would give us some way to see the pack temperature rather than have non linear bars. Same for soc.

 

[surfingslovak]

I would be interested in how these values compare to other folks' voltages.

Yes, this is why I've encouraged people to record pack voltages with their charge. One note about 80% voltages, though - until we're able to read cell-level voltages, there's 3 possible triggers the car can use to stop charging.

I think there must be a combination of effects going on: a moderate permanent loss of capacity on top of a seasonal loss from temperature. The timing of people losing bars at nearly the same time at the same place would fit with a seasonal effect. And since virtually no one had any sort of capacity measurement meter this time last year, we can't sort out how much comes from each.

It sure seems strange that all of a sudden many cars are showing a rapid loss in GID counts. Many people with low readings today were showing significantly higher readings as little as a couple months ago.

There definitely seems to be some sort of inverse correlation with temperature and GID count...

Yes, I posed the same question last year in a similar thread. Look at Luke's Gid plot for the past year. Although his battery might not be the best point of reference, it does seem to exhibit some seasonality. It would be really helpful if folks started noting pack voltage with their Gid count.

 

[mwalsh]

It's good to see a positive report amongst a sea of negative ones. Thanks for sharing.

Extrapolating from your figures (dangerous activity at best) you should be on target for 1.8% annual capacity loss. Which would mean you won't see the first capacity bar disappear until 2020 Comparing LA average temps to Nashville average temps I am encouraged that my results may be similar, all things being equal.

I'm sorry, but I can't agree with this analysis at all. 10 months/10,000 miles into ownership, during October in CA (which can be really quite warm indeed), I was still able to pull 281. And even when I wasn't pulling 281, I was pulling only a couple of Gids less pretty consistently.

 

[surfingslovak]

I'm sorry, but I can't agree with this analysis at all. 10 months/10,000 miles into ownership, during October in CA (which can be really quite warm indeed), I was still able to pull 281. And even when I wasn't pulling 281, I was pulling only a couple of Gids less pretty consistently.

Mike, granted, these numbers might be hard for us to rationalize, but it might be a bit premature to jump to any conclusions. We don't know if this was expected behavior due to a non-linear aging characteristic or individual variance in a few cars. I'm sure that this will become apparent as more information comes to the fore.

If memory serves, Boomer had a Gid reading of 257 last September. Recently, he was able to get 272, I believe.

 

[mwalsh]

If memory serves, Boomer had a Gid reading of 257 last September. Recently, he was able to get 272, I believe.

I've had some anomalies too, like a 91.8/258 during the same time frame in October I happened to be pulling the other numbers. I don't think one oddball in a raft of otherwise normal (and similar) readings can be viewed as a reliable datapoint. But I do agree it's too early to come to conclusions. That's why I'm resisting the temptation to get my car in for Nissan to examine just yet.

 

[surfingslovak]

I charge daily to 80%, occasionally charging to 100% when I know I need the extra range for some trip. The 100% charge happens perhaps up to 4 times per month. The car is always garaged at night, using an end timer to try and charge during the coolest part of the night. Usually parked in an open parking lot in the middle of the day, which is the best I can do - occasionally, I can get the rare covered parking spot. While parked in the heat, the SOC is typically 6 or 7 bars.

Thank you for sharing! If you don't mind me asking, are white and red the most popular Leaf colors in AZ?

 

[Weatherman]

I get the impression from reading all the posts that there's something more going on here than simple, "normal", battery degradation.

If the people seeing significant capacity losses were confined to the Phoenix area, or Texas (given how hot it was there last summer), you might be able to discount it as prolonged, excessive heat, but once you start including LEAFs from coastal Southern California in your sample, it's difficult to make the same argument.

Although I like my LEAF, and I believe that it will meet my needs for many years, I wouldn't consider buying a new one until a definitive cause of the early capacity loss is found. 15-20% loss in one year is not "normal".

By the way... even though I don't have a gid meter, I'm, pretty much, convinced that my LEAF's battery started out with about 5 to 8% less than what is considered nominal, new capacity. Not a big deal, unless it starts to degrade rapidly from there.

 

[surfingslovak]

I get the impression from reading all the posts that there's something more going on here than simple, "normal", battery degradation.

Although I like my LEAF, and I believe that it will meet my needs for many years, I wouldn't consider buying a new one until a definitive cause of the early capacity loss is found. 15-20% loss in one year is not "normal".

Point taken, Weatherman, and I hope you don't mind if I pointed out the obvious: there is very little data so far. We don't even know what the correlation between Gids and capacity loss is. If you took Mike's latest report at face value, a Gid reading of 222 should have led to a loss of a capacity bar. It didn't in his case, and I believe that LEAFfan has all 12 capacity bars as well. If I'm not mistaken, his last reading was 220. It's too soon to jump to any conclusions, but it won't hurt to collect more data. I believe that most of us see it that way.

 

[mwalsh]

 

[JPWhite]

Thanks for the regal reassurance

 

[mwalsh]

Thanks for the regal reassurance

I was going to go with "stroke the furry wall", but I didn't know how many of you would know 'Get Him to the Greek'. : )

 

[Weatherman]

Definitely no need to panic.

It's just the scientist in me is looking at the available data and saying, "Something just doesn’t quite add up."

 

[JPWhite]

Definitely no need to panic.

It's just the scientist in me is looking at the available data and saying, "Something just doesn’t quite add up."

BTW Weatherman. If you got an orphan LEAF, how come the delay between purchase and delivery?

 

[Weatherman]

Definitely no need to panic.

It's just the scientist in me is looking at the available data and saying, "Something just doesn’t quite add up."

BTW Weatherman. If you got an orphan LEAF, how come the delay between purchase and delivery?

It was the number of days it took to ship the car from Fontana, California, all the way across the country to my home near Ft. Lauderdale, Florida. (the $2,000 off MSRP deal was just too good to pass up)

 

[jkirkebo]

Well, all is well here in (cold) Norway at least. My car is 7 months old now, 5500 miles on the clock. It still gets 231 on every 80% charge. I checked the voltage now, 388.0V. On 100% charges I get 279-281 and sometimes 282 if I hit the timer override a second time a few hours after charging finishes. I don't think I ever saw below 279.

 

[vegastar]

The 80% voltage readings are taken how many time after the charge stop?
I notice that in my car the charge stops around 388.5V, but it always drops to 386 or 386.5V half hour later.

This morning I got 230 gids @ 386.5V with 6 temp bars.