Nissan Responds to LEAF Battery Capacity Loss in Hot Weather

By · July 26, 2012

LEAF battery

In May, reports surfaced related to potential battery capacity loss in a handful of Nissan LEAFs. All of the affected vehicles were driven in warm climates, in locations such as Arizona. Several owners of 2011 Nissan LEAFs said that one of the twelve lights on the battery capacity gauge had forever disappeared, indicating a possible 15-percent drop in battery capacity, according to the Nissan LEAF's workshop manual.

All of the affected vehicles had less than 17,000 miles on the odometer prior to the indicated loss of battery capacity and most were on the road for less than one year. Nissan's stance at the time the reports first surfaced was to brush it off as too minor to matter. "We’re aware of a few isolated cases where a very small number of consumers are reporting a one bar loss," said a company spokesperson. "Battery life is contingent upon many variables related to driving habits and conditions. We are confident that if owners care for their vehicles properly, they will experience many years of enjoyable driving."

LEAF Display

But Nissan is apparently now taking the issue more seriously. A recent post to Nissan's Facebook page announced that Carla Bailo, senior vice president of research and development for Nissan Americas, wrote an open letter to LEAF Owners on MyNissanLEAF.com, the forum whose community helped bring concerns to our attention.

"We are committed to working closely with our owners who have reported battery capacity loss to get answers that the LEAF community deserve in a timely and transparent manner," wrote Bailo. "Nissan engineers from our Arizona Testing Center and around the world will study each customer case, work to understanding the root cause and will determine next steps to satisfy our customers."

Nissan LEAF

For an in-depth read of the LEAF's potential battery capacity lost issues, check out the 180-plus pages of posts on MyNissanLEAF.com. It now seems this issue is not as isolated as Nissan suggested. Some LEAF owners now report losing a second and even a third battery capacity bar. Nearly all of those reporting capacity loss reside in either Arizona or Texas.

Nissan's decision to use a so-called passive air-cooled system—rather than a more complex and expensive active air- or liquid-cooled system—has come under criticism for more than a year. One of its harshest critics has been Tesla CEO Elon Musk, who predicted that the LEAF's battery temperature will be “all over the place,” and result in “huge degradation.” In the past, Nissan has said they are extremely confident that the LEAF batteries will perform reasonably well in both hot and cold environments, but that it will likely see a performance reduction to some degree when operating at extremes.

Comments

· · 1 year ago

I don't know if I'm witnessing a bit of historic revisionism here, but this article appeared on Plug In Cars a few days ago and people had already began to comment on it. Now, the submission date has been changed and all the old comments have been removed. Perhaps Eric updated the text (I don't have the original to compare it to, so I can only speculate)? Hmmm . . .

In any event, here's the idea I had previously posted here regarding a newly developed passive battery cooling system . . .

http://www.dailytech.com/article.aspx?newsid=25158

OK, now that this has been done, I'll sit back and wait for the various gasoline range extender nazis and fuel cell fascists to log on here and remind us that the only good pure EV is a dead pure EV.

:-)

· Anonymous (not verified) · 1 year ago

Anyone who worked on lithium battery technology will not be surprised by this at all, I mean LiMn2O4 is very sensitive to heat.
GM did a much better job, but even that one I douby it will last >8 years, because GM uses pouch cell, it is subject to venting, all you need is one to to fail, you are going to damage the whole battery pack.
Waiting for that to happen!

· Iletric (not verified) · 1 year ago

I like that 132 on the dial. Too bad it's kilometers... :-(

· · 1 year ago

The paraffin cooling idea is nothing new under the sun. It was actually used on the electric Moon rover to cool the systems in absence of atmosphere. Each rover had a total of 2 Kg of paraffin on board that served as a heat sink by melting above a certain temperature. Nevertheless the idea to use it down on earth EV’s is interesting.

· Anonymous (not verified) · 1 year ago

"I'll sit back and wait for the various gasoline range extender nazis and fuel cell fascists to log on here and remind us that the only good pure EV is a dead pure EV." - Benjamin Nead

Nah, we don't need to do that as those all-electric vehicles will do it for us. Gas back-up rules !

· · 1 year ago

@Anonymous,

"GM did a much better job, but even that one I douby it will last >8 years, because GM uses pouch cell, it is subject to venting, all you need is one to to fail, you are going to damage the whole battery pack.
Waiting for that to happen!"

A single cell failure will not take out the Volt's battery. Their are 288 cells contained in 9 modules. At most you would lose a module, not the pack. The Volt's battery if anything is probably over engineered. Nissan's design allowed them to get a car out fast.

· Anonymous (not verified) · 1 year ago

theflew

I am a scientist with PhD in lithium battery R&D, when one cell fails, if the cell bulge, the battery pack id dead, if a cell just fail without any physical damage, the durability/robustness of the battery pack is seriously compromised and cycle life reduced, also there is no way to put another cell cell to replace the old one, the whole thing has to be changed, that is why this technology is difficult, all 288 must be highly consistent!

· Anonymous (not verified) · 1 year ago

@theflew
Having worked with lithium batteries for a number of years, I know that it is possible to replace a single cell in a battery pack. The pack's performance will be governed by the weakest cell. So if the the rest of the pack is 3 years old it will perform like a 3 year old pack, in terms of capacity, etc.

· Anonymous (not verified) · 1 year ago

@theflew
Having worked with lithium batteries for a number of years, I know that it is possible to replace a single cell in a battery pack. The pack's performance will be governed by the weakest cell. So if the the rest of the pack is 3 years old it will perform like a 3 year old pack, in terms of capacity, etc.

· Anonymous (not verified) · 1 year ago

You must be aware that once you replace the bad cell out of a 3-y old battery pack, the degradation will accelerate compare to the old one, right?
You are right about the capacity, but the real problem is how to ensure longevity of the battery pack once the cells are not uniform in terms of capacity and degradation rate.

· · 1 year ago

Looks like it is past time for an article summarizing all the known knowns, etc for all of us know-nothings. I live in a hot climate (not Phoenix) but so far have had no definitive problems with my LEAF battery. My 80% charges were for a while lighting 9 rather than the 10 charge gauge bars that had been lighting up since I first got the car. But it has reverted to 10. I may have lost a mile or two in my distance test but even that is not definitive. The moment of truth is going to come in about two years when I have to decide whether to buy out my lease or return the LEAF. From the discussion it sounds like, in spite of the LEAF battery’s modular construction, replacement is still basically an all or nothing proposition. I guess the specific question is: if a module is replaced will it degrade faster than it would have if it had been replaced as part of a battery swap out?

P.S. Answers to any other questions I don’t know enough to ask would be appreciated?

· · 1 year ago

I didn't read though the entire MyNissanLeaf Forum postings on this issue (it's now up to around 200 pages,) but I did skim through about the last 10 or so pages. One item that caught my eye was someone noting that Nissan, apparently, already has some sort of active battery cooling systems for Leafs being sold in Middle East countries. Anyone know anything more about this?

· · 1 year ago

@Benjamin - Thanks for the tip! There is a full thread on the 9 bar / 80% charge topic - http://www.mynissanleaf.com/viewtopic.php?f=30&t=8765 ("80% Charge only 9 bars?")

Is there a way to cheaply and accurately measure the actual stored electrical energy in a LEAF battery in KWH? If there is, it seems to me this ought to be one of the values displayed in the numeric state of charge indicator Brad has been asking for.

· EVsRoll (not verified) · 1 year ago

140 degrees is hot even for the U.S. desert southwest. Climate change could be pushing temperatures higher on an annual basis.

Ironic that the Leaf battery pack is affected by climate conditions which it is partially intended to repair.

EVsRock!
http://www.evsroll.com

· · 1 year ago

Well, this is very interesting, world2steven. Thanks. On the 3rd page of the link you provided (haven't made it through all 12 pages yet,) there's a link within one of the posts to yet another rather large MyNissanLeaf thread (something like 34 pages!) that shows a prototype for something called Leafscan: an LCD instrumentation panel that featured a 5 digit resolution state of charge (SOC) indicator . . .

http://www.mynissanleaf.com/viewtopic.php?f=37&t=8251

Getting back to the thread you posted in your message, I note that many of these Phoenix-based Leaf owners have managed to move their 9 bar dash indicators back to 10 bars with cleaver charging techniques. All very interesting. I need to read through all this stuff and start taking notes.

Incidentally, I'll have a local friend's Leaf dropped off here on Tuesday, which I'll be watching for him for about 2 1/2 weeks, while he's out of town. Should be fun to be actually driving an EV, instead of just talking about it.

Still wondering about the purported Leaf active battery cooling system alleged to be slated for Middle East markets. If Nissan has something like this on their shelves, it could provide a happy ending to all of this hot climate FUD.

PS to EVsRoll: I was thinking exactly the same thing.

· · 1 year ago

@Benjamin - Thank you! Remind me to send you the links to everything that might be potentially interesting but on which I don't make it past the first page. The SOC indicator looks like a must-have add-on for aging LEAF battery owners - providing it doesn't violate warranties and is affordable. I wonder if there is any way for a dealer to determine the battery's charging potential without having to fully charge it?

P.S. Let's do a sandwich and beer at 1504 sometime. You work at KUAT, right?

· · 1 year ago

Yup, that's me. I'm in and out a lot this week but, if you happen to hear me on air, give a call to the station and the front desk will transfer you over to the KUAZ booth. When we get together, I'll fill you in on what's being planned for National Plug In Day on September 23.
The cards have fallen into place just today in regards to an event.

· · 1 year ago

The two Leafs were among seven tested by owners in the Phoenix area last week. In the test, the Leafs, with varying mileage and battery capacities, traveled a per-determined route until they ran out of power. The results showed their battery capacity had degraded more quickly than the “80 percent remaining capacity after 5 years” claimed by Nissan. The worst made it only 59 miles and had lost more than 60 percent of its charge capacity.

· Anonymous (not verified) · 1 year ago

The only cathode material suitable for long term performance of large Li-ion battery pack is LiFePO4 coated with carbon. Unfortunately for Leaf owner's, it seems that Nissan don't understand that yet and customer pay the price of Nissan bad technology choice.

· · 1 year ago

diane009:

So... are Andy Palmer, Mark Perry, and Carlo Bailo of Nissan lying to say that the capacity loss in 7 LEAFs analyzed in AZ was "consistent with their usage and operating environment"?

My reading of the data from the 12 cars tested by the owners is that 10 were within reasonable projections according to the mileage on their odometers. Two others, however, were lower than anticipated, but their results are likely due to other factors besides just heat, since the other 10 cars do not show the same level of deterioration. That car with the highest mieage, 29,000, achieved 59.3 miles on the test, but according to an extrapolated calculation using Nissan's own benchmarks (76 miles when new), the minimal range expected would be about 69 miles. 9.7 miles less than that on the test does not represent a 60% loss of capacity. 59.3 / 76 = 22%

http://bit.ly/P7amaF

What I would like is to see the CarWings data on that vehicle, to learn how it was driven, charged, how often, under what circumstances, 100% vs. 80%, etc.

· · 1 year ago

@ Yanquetino, Nissan & EV Evangelists
Thanks for the comments and particularly the link to http://www.casteyanqui.com/ev/capacity_kerfuffle/index.html. The author raises some points about the LEAF ‘Arizona problem’ the more general ‘capacity kerfuffle’ over the LEAF’s battery. LEAF owners and others considering becoming one or leasing a LEAF would be well-advised to read the article before making any hasty decisions about acquiring or disposing one.

That said, I came away with the impression that the article may let Nissan and those of us who believe electric vehicles are the future of personally owned transportation – if there is going to be one – off the hook too lightly for excessive claims for BEVs. For starters, even the low-ball estimate of a 76 mile range is probably 20% too high if drivers are going to be repeatedly fully charging and discharging their batteries. The cost in terms of accelerated battery degradation needs to be made clear to prospective drivers at the outset. Any users for whom this deep charge / discharge cycle is necessary is pushing the performance envelope of current battery technology. Disappointments and dissatisfaction are almost inevitable.

Then comes workload, i.e. the kind of driving that will be done with the LEAF under a worst-case, most demanding scenario. In my case it involves climbing about 6000 feet in a little over 30 miles – for perhaps four or five months of the year with ambient air temperature approaching or exceeding 100 degrees. Under those conditions, the range of a LEAF is AT MOST about 40 miles. It is now pretty clear that Nissan’s decision to not protect its battery with an active thermal management system, at least for customers in climates with extreme temperatures like Arizona was a mistake. It is a mistake for which Nissan needs to take responsibility – a responsibility those of us who had hoped the LEAF would become the Volkswagen, the ‘people’s car’ of electric vehicles should not help or encourage Nissan to evade.

· · 1 year ago

@world2steven,
" . . . Volkswagen, the ‘people’s car’ . . . "
Interesting you should pick the VW. I remember often seeing the old VW micro busses burning at rest areas because their air cooling couldn't handle stopping after being driven hard. Imagine what folks would say today if someone tried to sell a car as unsafe as the old vee-dubs.
Nissan has no thermal problems compared to that.

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