Nissan LEAF battery capacity loss – Third in a series

by Ernie Hernandez on August 11, 2012

Standard deviation diagram

How pervasive is the problem of battery capacity loss in the Nissan LEAF?

To recap for those just joining this discussion – this is the third in a series of articles regarding the issue of battery capacity loss in the Nissan LEAF. Our first two articles can be found here (first article) and here (second article). This discussion thus far has covered over 250 pages on the My Nissan LEAF forum. We are working our way through every post from the first to try to better understand the issue from the owner’s perspectives. Thus far we are up to page 80.

As we continued our reading of the My Nissan LEAF (MNL) forum topic regarding the battery capacity loss issue of the LEAF, we found as each week went by other LEAF owners were reporting that either they had lost a battery capacity segment, or some reported of knowing others that had. Near the end of these posts, we read a brief post indicating that 17 of roughly 25,000 LEAFs sold world-wide (the then current number affected by the problem) accounted for less than one tenth of one percent of all LEAFs produced. According to the forum wiki, the number is now up to 54. No doubt this discussion has progressed in future pages, which we will read eventually, but this did provoke a response from several forum members that the universe should be confined to Phoenix or even just Southwest area owners. The individual that made the original post stood her ground and said that the proper universe should include all cars sold globally as it is not known if similar conditions exist in other areas. She also made another extremely important observation – we don’t know how many or where other LEAFs may be impacted by this same condition, which is why all LEAFs sold must be considered in the sample universe.

In reviewing the latest list of one segment battery capacity lost owners, the geographic universe now includes a handful in Texas and California along with the rest which mostly reside in Arizona. Of the California cars, one report is from the moderate climate of San Diego, which goes against the hot climate theory. In reviewing the notes accompanying the San Diego car’s wiki entry, this particular LEAF accumulated over 25,000 miles in 14 months and the battery was drained to “turtle” mode about 20 times in that 14 month period. Given that this is only one example, one must consider the possiblity that frequent use of the entire usable battery capacity may also be a contributing factor to this issue. Then again, accumulating 25,000 miles in 14 months and using the entire usable battery capacity perhaps 20 times during that time frame is likely outside the norm regarding typical vehicle usage. (EDIT: Based on a comment to this post, and upon reviewing the original post by the owner, this San Diego car did not lose a bar as reported. The owner thought it was about to lose a bar when he sold it.)

In looking at the MNL wiki, it seems that one column of the table is now formatted for “Case Number”. As there is no legend to the table on the wiki page, we can only assume that these are Nissan case numbers assigned as these cars have been reported to Nissan.

Getting back to our original question – how pervasive is this problem? The only entity that knows that is Nissan. And we don’t know if they are fully aware of all of the vehicles impacted if the owner has not notified them. But let’s get hypothetical for a moment. Let’s just say that as many as 200 vehicles are impacted globally. That number is still less than one percent of all LEAFs sold globally to date. Which means that more than 99 percent are not impacted. Certainly this number will continue to grow, and we are not attempting to sidestep that part of the equation. But as it stands now, statistically speaking, this is still a very small percentage or even fraction of a percentage of the entire universe. And this is the point that all Nissan LEAF owners or prospective LEAF owners must keep in mind. A statistical outlier is called that for a reason – it is not the norm. And based on the number of case numbers (31 at last count) that we saw posted on the MNL wiki of LEAFs reported on the MNL forum, Nissan is taking this seriously.

It would be unreasonable to expect a resolution in a week or two. Granted, it has been much longer than that since the first reported case on the forum in May. Early problems were reported to local dealers, but we don’t know if those local dealers were reporting anything further up the food chain. Nissan North America may not have been made aware of the problem initially. Now the corporation has been notified, by at least 31 LEAF owners, and Nissan is looking more closely at each of these situations. With the financial commitment that Nissan has made to the success of electric vehicles globally, one can be certain that they are commiting vast resources to the study of these vehicles and their use history. We imagine that each battery pack is being evaluated cell-by-cell to determine if it is a manufacturing defect or an issue of chemistry. Nissan will also closely examine the vehicle usage history to see how closely owners complied with Nissan’s recommendations regarding battery care. For those LEAF owners following this saga carefully, we will refer you back to our prelude to this series – Care and feeding of the Nissan LEAF battery.

 

{ 8 comments… read them below or add one }

edatoakrun August 12, 2012 at 12:25 pm

“…Of the California cars, one report is from the moderate climate of San Diego, which goes against the hot climate theory. In reviewing the notes accompanying the San Diego car’s wiki entry, this particular LEAF accumulated over 25,000 miles in 14 months and the battery was drained to “turtle” mode about 20 times in that 14 month period….”

I believe that this LEAF is erroneously listed as having lost a bar.

The owner stated he THOUGHT it was “about to” lose a bar, when he sold it.

Good luck again, in gleaning the pertinent facts, from the thousands of posts on this thread.

If you want to read a far shorter thread, with my suggestions of how to asses LEAF Battery capacity, as accurately as is currently possible, look here for my suggestions,and my most recent results:

“…And I reported that in both recent tests, CW indicated 17.5 kWh use in both recent test from 100% charge to just past VLBW, as opposed to 18.7 in my first test, last Summer.

So, in the simplest analysis, I could conclude this about a 6% reduction in battery capacity was evidence of “degradation”.

However, I believe that there are other factors which cause both the “100%” charge level, and the level of the LBW, to occur at different levels of total capacity.

And I would not make any assertion, of what part of this reduction was a permanent loss in battery capacity, as opposed to a reduction in access to my total battery capacity, imposed by my LEAF’s battery management system….”

http://www.mynissanleaf.com/viewtopic.php?f=31&t=9064&start=0

As of today, I still have all 12 bars of capacity, and will be updating this thread in the future.

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Ernie Hernandez (LEAFguy) August 13, 2012 at 11:34 am

Thanks for the clarification regarding the San Diego car. I have edited the article to reflect that. I will watch your other topic thread for future updates.

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Steve August 12, 2012 at 11:01 pm

With many 2011 cars going in for their one year battery inspection, Nissan should have a large trove of data to mine at this point. We did our one year a week ago (about 3 weeks early) at 15000 miles still at 12 bars. Hopefully the data gathered and sent to the factory is more detailed than what the owner is provided…

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Ernie Hernandez (LEAFguy) August 13, 2012 at 11:41 am

Steve – undoubtedly Nissan is harvesting more information from the onboard computers than they share with vehicle owners. The same could be said of any vehicle taken in for service. With every additional LEAF’s one year inspection report Nissan’s database is getting better. That said, we don’t know exactly how much information is pulled from the car in these reports. My suspicion is that the lost-battery-segment cars will be submitted to closer scrutiny than those with a routine annual checkup with that closer inspection involving a deeper dive into the electrons.

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Rune August 15, 2012 at 3:51 am

“…17 of roughly 25,000 LEAFs sold world-wide […] accounted for less than one thousandth of one percent of all LEAFs produced”

One thousandth of one percent is, as far as I know, 1/100000. Are you saying that over 1.700.000 (17 * 100000) Leafs are produced)?

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Ernie Hernandez (LEAFguy) August 15, 2012 at 7:23 am

Rune, Welcome to Living LEAF. Sorry about the incorrect math. I’ve edited the entry to correct the error.

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Stoaty August 31, 2012 at 10:04 am

The correct denominator is the 400 Leafs sold in Arizona. Over 10% (44 to be exact) of those have been reported to have lost a bar on the Wiki. It is likely that the actual number of Arizona Leafs that have lost a bar is much higher, since most probably aren’t reported to the Wiki

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Tony Williams September 4, 2012 at 10:40 am

Hi LEAFguy,

Since my car seems to be of interest to you in this piece, I thought I’d comment. My San Diego LEAF, serial #2244, that I purchased May 2, 2012, did not lose a capacity bar, however it was approximately 15% reduced in range performance since purchased new. This data was not measured from the wildly inaccurate “GuessOmeter” on the dash, but actual road performance here in San Diego. In addition, many of the mega-geeks like me extract the data reported by the car concerning battery stored energy, measured in 80 wattHour units. Based on this measurement, as reported by my LEAF, my car was only about to store approximately 85% of its new capacity. My car is currently at the CarMax store in Irvine, and I’m happily driving a new leased LEAF.

Since your posting of this article, several LEAFs in San Diego and southern California have reported the infamous first capacity bar loss, indicating a 15% loss in battery capacity. It would seem that driving my car to turtle (where the car stops because of a depleted battery) 20-ish times is a bit of a red herring, because these other cars were typically NEVER driven to turtle. My car was rarely exposed to temperatures over 90F, so there was not a specific “heat” factor in my car’s losses, or other similarly exposed San Diego LEAFs. That should actually be alarming to you.

In a nutshell, it’s no surprise that I don’t agree with the direction of your article. Every Nissan LEAF was produced with exactly the same battery. If I took your LEAF from San Diego, and placed it in Dubai, Phoenix, or most of Texas, and now even Hong Kong that has reported a loss, your car would likely exhibit the same conditions; high ambient heat accelerates battery degradation. Sure, there are no doubt other factors, like percentage of time the battery is left at 100% charge, miles, number of cycles, and even number of times to turtle.

All the LEAF batteries will degrade. That is normal for a car that uses 93% of it’s rated capacity, and has no means to mitigate the effects of heat. In contrast, the GM – Chevrolet / Holden “Volt / Ampera” electric car will not likely have the same issues, since it’s battery is kept cool with a system designed to do that, and secondly, only 60% of the battery is available for the car’s use.

If you’re interested in my summary of the LEAF battery woes, you can find them here:

http://www.mynissanleaf.com/viewtopic.php?p=220120#p220120

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