Capacity Loss on 2011-2012 LEAFs

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edatoakrun said:
And clearly, there is a correlation of capacity bar loss with both time and miles driven, whatever adjective you use to describe it.

If bar loss was not correlated to these factors, and an entirely random event, then the entire field of your graph would have equal distribution.
...

Both of these factors might be expected show far greater correlations in cooler climates. Even more so, if they are restated as time from delivery, and number of charge cycles. But in Phoenix, both of these individual factors are themselves probably reflecting (in varying amounts) a much "strong"(er) correlation, to exposure to high battery temperatures.
Good points, if you recall I evaluated a small but geographically dispersed sample three months ago. I used Gid counts, because none of these folks have lost any capacity bars at the time. While I realize that Gids do not equal permanent degradation, they do represent a capacity reading, and I hope that if nothing else they can be used as a proxy for capacity degradation. That said, the sample showed very clear correlation to average ambient at the place of residence (around 70%) and weak correlation to vehicle age and miles driven. This was suprising, since it was previosly believed that cycling losses, and by extension mileage, will play a pivotal role.

When I saw how much larger the dependence on ambient temperature was when compared to the other two factors, I rang my private alarm bell, and let a few people know about it. Unfortunately, they did not see or want to believe the significance of the data they were looking at. It was difficult to argue otherwise given the sample size and the type of data used (Gids).

I would not be at all surprised to see stronger correlation to mileage than my original sample implied, if you restricted yourself to a particular locale (hot or cold), just like what Stoaty's plot showed. This is my personal opinion, but I do not believe that what we see in Phoenix is in any way abnormal, we are just seeing it sooner due to elevated ambient temps. It seems to be accepted practice to cycle batteries in a temperature controlled chamber to accelerate aging and get test results sooner than it would take at normal room temperature.
1
 
I analyzed the Leafs in Texas that lost a capacity bar, but didn't find a correlation with monthly mileage and rate of capacity (correlation coefficient = 0.013). Perhaps this was due to there being too few Leafs in the sample with a few outliers, or maybe the climate varies enough between the various cities to allow for a meaningful comparison. Interestingly, the average rate of capacity loss was 1.2% per month, similar to the average 1.3% per month seen in the Phoenix metro area sample (latter not previously reported, I believe).

Data below:

texasonebardata.jpg


Graph below:

texasonebarlosers.jpg
 
Guidelines for purchase or lease added to Wiki section on battery capacity:

"Guidelines suggested by Weatherman on whether the Leaf is likely to experience temperature related accelerated battery capacity loss in your area:

If you almost always see five bars or less on the battery temperature gage, and it only gets up to six bars a handful of times each summer... Don't worry about it.
If you see five bars or less during the winter half of the year, and fairly often see six bars during the summer half... You probably are going to see the loss claimed by Nissan (20% loss at 5 years and 30% loss at 10 years).
If seeing six bars is common for a large part of the year, and a seventh bar pops up occasionally during the summer months... Don't consider buying. Lease would be OK.
If you spend a large part of the summer with seven temperature bars or more showing... It's probably best to avoid the Leaf completely. Consider an EV with an active thermal management system or the Chevy Volt."

You can inquire on the forum how many battery temperature bars others who live in your area are typically seeing.
 
Stoaty said:
Guidelines for purchase or lease added to Wiki section on battery capacity:

"Guidelines suggested by Weatherman on whether the Leaf is likely to experience temperature related accelerated battery capacity loss in your area:

If you almost always see five bars or less on the battery temperature gage, and it only gets up to six bars a handful of times each summer... Don't worry about it.
If you see five bars or less during the winter half of the year, and fairly often see six bars during the summer half... You probably are going to see the loss claimed by Nissan (20% loss at 5 years and 30% loss at 10 years).
If seeing six bars is common for a large part of the year, and a seventh bar pops up occasionally during the summer months... Don't consider buying. Lease would be OK.
If you spend a large part of the summer with seven temperature bars or more showing... It's probably best to avoid the Leaf completely. Consider an EV with an active thermal management system or the Chevy Volt."

You can inquire on the forum how many battery temperature bars others who live in your area are typically seeing.

i think 6 is fine.
 
thankyouOB said:
i think 6 is fine.

There's, definitely, a lot of mischief that can hide in that sixth bar.

I'm sure a lot of people will see six bars every summer afternoon and evening, but will it drop to five bars at night. It might even stay at six bars for 24-hours a day for a few days during the summer. Southern California coastal residents can correct me if I'm wrong, but it seems like that's pretty typical for that area. Anecdotal evidence suggest that, unless you rack up lots of miles in that environment, the battery's probably going to last as long as Nissan claims it's going to last. If that's fine with you, then good.

The real unknown is those of us who see six bars, 24-hours a day, for week, after week, after week (or, in the case of Florida, for month, after month, after month), but rarely if ever see a seventh bar. There is, essentially, no information, yet, as to what happens under those conditions. It might be ok. It might not. That's why I suggested lease-only for that third group.

We already know what happens if the infamous, seventh bar shows up a lot. I don't think there’s any question that if you are seeing seven bars a lot, the battery is degrading relatively quickly, and you have to decide if you can live with that.
 
So far since I bought my car in June, I've consistently seen 6 bars and rarely seen a 7th bar and I'm right here in the same area as many of those people in Texas who have lost a bar, so I'll have to agree with Weatherman, there's a lot of mischief that can hide in that 6th bar. I'm not so sure 6 bars is fine.
 
I'm here in So Cal (inbetween LA and Disneyland) and I have seen 5 tb twice in the morning and the rest of the time has been 6tb. (i have had the car for 1 month now) I'm glad this 2 week heat wave is about over. I hope I will see more 5tb soon. So far I love this car and right now I am kinda sad to think I have to gvie it back in 38 months.

Neal
 
Weatherman said:
I'm sure a lot of people will see six bars every summer afternoon and evening, but will it drop to five bars at night. It might even stay at six bars for 24-hours a day for a few days during the summer. Southern California coastal residents can correct me if I'm wrong, but it seems like that's pretty typical for that area.
My car hasn't seen 5 bars in probably 2 months - and then it was only briefly in the morning a couple times. It's probably been 3 months since the battery has held at 5 bars for any significant time.

I live about 4 miles from the ocean.
I work about 7-8 miles from the ocean.

I highly doubt anyone in San Diego has seen 5 bars much in the last 2 months unless they live within a mile of the ocean and park outside, or live further inland where it cools down more at night and they park outside at night.
 
Stoaty said:
I analyzed the Leafs in Texas that lost a capacity bar, but didn't find a correlation with monthly mileage and rate of capacity (correlation coefficient = 0.013). Perhaps this was due to there being too few Leafs in the sample with a few outliers, or maybe the climate varies enough between the various cities to allow for a meaningful comparison. Interestingly, the average rate of capacity loss was 1.2% per month, similar to the average 1.3% per month seen in the Phoenix metro area sample (latter not previously reported, I believe).

I think you find it more difficult to analyze the Texas data. For example, Houston has a more average temperature being next to the coast, summers don't get as hot elsewhere, but don't get as cool either, getting more of a warm/hot coastal feel. Then when you look at people living in the urban areas of Dallas-Fort Worth/San Antonio/Austin you may get a more localized "heat island" effect versus those living in the surburbs that could see a more cooling since Texas cities are very spread out.

You may be able to get better results if you isolate climate types, i.e. Houston as a costal, DFW as plains, Austin/San Antonio as Hilly Plains (could be similar to DFW) and anywhere out west as Desert/Plains/Scrublands. But, you probably will run into low data at that point. Texas could see similar problems as California in interpreting results. You have nice cool coastal cities, cooler moutain places, and hot desert areas.
 
drees said:
My car hasn't seen 5 bars in probably 2 months - and then it was only briefly in the morning a couple times. It's probably been 3 months since the battery has held at 5 bars for any significant time.

I live about 4 miles from the ocean.
I work about 7-8 miles from the ocean.

I highly doubt anyone in San Diego has seen 5 bars much in the last 2 months unless they live within a mile of the ocean and park outside, or live further inland where it cools down more at night and they park outside at night.
I live 3 blocks from the ocean in the coolest microclimate in SD and we have also spent the last several months at predominately 6 TBs. Never seen 7 yet, but 5 bars have not been seen on our car for some time now.

TT
 
The last time I saw 5 bars was about 7 months ago in winter. I did, however, see 7 bars briefly during our heat wave here last week.

drees said:
My car hasn't seen 5 bars in probably 2 months - and then it was only briefly in the morning a couple times. It's probably been 3 months since the battery has held at 5 bars for any significant time.
 
the "tipping" point between 5 and 6 bars is a hair above room temperature. up until mid July, i always saw 5 bars in the morning. if i charged, i was usually done by 3-5 AM, taking off at 8, temps in garage low to upper 60's.

now, the temp in garage is not much different. mid to upper 60's but temperature during the day (in garage) has gone from low to mid 70's to low to mid 80's and now i am at 6 TBs all the time as well but the telling statistic is how much time it takes to cool down from very warm temps.

the biggest issue i see is the gradient scale. they should have been made the same. having 20 something for one bar and then less than 5 for another means you essentially get no warning until its too late. iow, we are right back to idiot lights. by the time they come on its too late.
 
neal77 said:
I'm here in So Cal (inbetween LA and Disneyland) and I have seen 5 tb twice in the morning and the rest of the time has been 6tb. (i have had the car for 1 month now) I'm glad this 2 week heat wave is about over. I hope I will see more 5tb soon. So far I love this car and right now I am kinda sad to think I have to gvie it back in 38 months.
Neal

You don't have to give it back, unlike the EV1. You can buy it for the residual when your lease is up.
 
LEAFfan said:
neal77 said:
I'm here in So Cal (inbetween LA and Disneyland) and I have seen 5 tb twice in the morning and the rest of the time has been 6tb. (i have had the car for 1 month now) I'm glad this 2 week heat wave is about over. I hope I will see more 5tb soon. So far I love this car and right now I am kinda sad to think I have to gvie it back in 38 months.
Neal

You don't have to give it back, unlike the EV1. You can buy it for the residual when your lease is up.

Today (after a 80% charge to 10 bars), the first bar only lasted 1 mile. is this an early indicator that i am going to lose a capacity bar?
 
chris1howell said:
Last night I joined the "Lost a bar" club. Here are my basics:

Location: Lancaster, Ca
Miles: 15600
Months: 14

Added to the Wiki.

chris1howell, can you give us your car's manufacture date (located on the metal plate inside the driver's side door on the frame) and let us know the date and case number if you've reported the capacity loss to Nissan. Thanks!
 
TonyWilliams said:
The next time OrientExpress gives us the next LEAF revelation, just consider these previous revelations about the battery:


1. "So far, all of the posts on this subject are speculation, hearsay, innuendo, and opinion."

2. "In reading through all the cases, I really don't see a problem"

...

17. So, it might be a software problem... "What if this whole thing is just a SW bug that is not accurately reporting the capacity of the battery?" A bit later, that was upgraded to, "reputable highly-placed sources suggest that a software bug". Naturally, no data to support this, or any other claim.

18. Some very specific and detailed data from most detailed person on the forum is just tossed aside with... "your methodology does not support your conclusions". This is from somebody that really hasn't provided ANY data.

19. Another "theory" with no data to support it (nor was any offered), "only those cars that have been driven in a severe and high-mileage mode trigger the condition."

OK, I'm not saying there isn't a problem, and I'm not sure if anywhere in the previous 290 pages this has been addressed, but in the Owner's Manual it states, on page 2-9, "When the Li-ion battery becomes warmer, less segments on the Li-ion battery available charge gauge illuminate because the remaining energy is a lower percentage of the Li-ion's battery's capability of storing power.". So the way the manual sounds, people in the high heat areas aren't losing capacity, they are gaining potential capacity? And it also sounds like even with the higher potential capacity, the LEAF only will charge to fill a normal potential capacity battery.

One other question then is are lost capacity bars the best way to be studying the problem?

One other observation about point #18 is that OrientExpress did provide some data, that his car is apparently functioning without any problems. And I keep thinking that LEAFs without any apparent capacity problems need to be included in the data too.
 
sub3marathonman said:
One other observation about point #18 is that OrientExpress did provide some data, that his car is apparently functioning without any problems. And I keep thinking that LEAFs without any apparent capacity problems need to be included in the data too.


watch out, sub3; someone is going to ask you to exchange your car for a Phoenician Leaf.
 
sub3marathonman said:
people in the high heat areas aren't losing capacity, they are gaining potential capacity? And it also sounds like even with the higher potential capacity, the LEAF only will charge to fill a normal potential capacity battery.

One other question then is are lost capacity bars the best way to be studying the problem?

Honestly, I really do not believe your thoughts have merit. The lost capacity bars are explicitly identified as the method to indicate loss of capacity. So, saying otherwise suggests that Nissan made a mistake with their capacity indicator.

The only real way to indicate RANGE is to measure it. Many people have, as I have, many, many times.

The heat issue of GAINING energy is certainly true, if the batteries weren't also degrading during the process.
 
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