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Nissan responds to Leaf owners' massive test in battery aging case

Nissan unveils more data in the battery capacity loss controversy, saying that the culprit is total driving distance, not heat, and that the battery packs are behaving as expected considering the heavy use.

The controversy over Nissan Leaf battery pack capacity loss is getting deeper, following a statement from Nissan published through Green Car Reports, and a response published by EV Owner Tony Williams writing on InsideEV's. Nissan's response that range loss is occurring for Leaf's that have been driven a long distance, but Williams counters with evidence that contradicts Nissan's claims.

As TorqueNews noted earlier, a group of Phoenix-are Nissan Leaf owners staged a test last weekend to verify claims of battery pack capacity loss. This lost capacity would result in a shorter driving range than Nissan claims for the Leaf, and if true would make the Leaf a less-useful car. The issue has been under discussion on the MyNissanLeaf forum for months, leading Nissan to issue a statement saying they were studying the issue.

In July, Nissan brought seven Leaf's to its technical unit at its Arizona Testing Center for a technical assessment. Nissan collects data from each Nissan Leaf and has found that the 450 Leaf's currently in Arizona are on a path which will result in 76% capacity after five years, rather than the 80% capacity Nissan had expected. Nissan's published claims of expected range loss over time were based on an average driving distance of 12,500 miles/year in climates similar to Los Angeles. The seven Leaf's examined closely by Nissan had all been driven much further than the average, some well over 20,000 miles/year.

To complicate this, Nissan additionally says the geographic layout of Phoenix makes the problem worse. Driving at highway speeds requires more energy, and is harder on the pack, than is driving at city street speeds. Because Phoenix is a sprawling city where highway speed travel is more common than city speed travel, Leaf's in that city have a harder life than those in other cities, according to Nissan. The argument is rather technical, but battery pack life is actually not measured in its calendar age, but based on the total usage the pack has seen (kilowatt-hour throughput). With a full charge a Leaf driven at highway speed might travel as few as 50 miles, but driven at city streets speed could travel as far as 100 miles.

Nissan's Mark Perry told Green Car Reports, ”The cars and the battery packs are behaving as we expected”. This may be little comfort to the affected Nissan Leaf owners because Nissan had published certain claims about range, and range loss over time.

Indeed, an article on InsideEV's responding to Nissan's statements in the Green Car Reports article characterized those statements as their "latest excuse."

That article notes that the seven Leaf's tested by Nissan were hand picked, by Nissan. InsideEV's claims there are 147 Nissan Leaf's in the Southern US that have at least one bar of capacity loss, 47 of which have been driven less than the 12,500 miles/year threshold stated by Nissan.

Tony Williams claims that his own Nissan Leaf, the one he drove on the BC2BC trip (Baja California to British Columbia) in June, has already suffered enough battery capacity loss that he could not make that same trip today. He lives in San Diego, an area that does not suffer from a hot climate.

In other words, Nissan's claims may not be solid enough to hold water.

The problem has both technical and corporate goodwill aspects to it.

Nissan started this out by claiming, two years ago, that the Nissan Leaf would experience 80% remaining capacity in five years. Thousand's of Leaf's have been sold with the Leaf owners understanding that promise. However we now see from Nissan a highly nuanced claim of the expected normal battery capacity loss. That is, maybe heat can damage the Leaf battery pack, or maybe it can be damaged from heavy use, and maybe next week Nissan will talk about another causitive factor. Today it's not as straightforward as Nissan originally said, but depends on this and that and something else.

Technically these causes Nissan has named are plausible, and technically sound. In the case of product scandals, do plausible and technically sound arguments win the hearts and minds of the affected customers? Not often. In particular, does the shifting and highly nuanced story cause Leaf owners to continue feeling goodwill towards Nissan? Will worried Leaf owners have the patience to understand the nuances to Nissan's latest claims? What will Nissan do to win back the goodwill of their current and future customers?

Source: Green Car Reports


Arizona EV Pilot (not verified)    September 23, 2012 - 1:15AM

Interesting events David, thank you for reporting on this. As a Phoenix leaf owner for 10 months now, I feel compelled to answer your questions at the end of your artical:

Nissan's explanation does not win my heart or mind. Originaly my heart was in love with Nissan and the leaf. Then once the battery bars started rapidly disappearing, Nissan was cold, unresponsive and i quickly found the original information to be grossly incomplete. My mind calculates what Nissan is now saying and equates it to consumer fraud - and I want nothing to do with this any more(I had enough after my 2nd bar loss). The leaf ownership relationship now is like a marriage that was entered into with a massive lack of disclosure to make an informed decision; the honey moon is long over, and I am praying for divorce paperwork or an FBI raid (like what happened so Solyndra).

I am observing that the shifting story from Nissan is exactly that, shifty. I want to note that I have documented my problems directly/regularly with Nissan for over 4 months and have had no good will from Nissan USA. I have to read updates about the issue online for goodness sakes. This was a damn expensive car, why can they not call me to tell me they are re-nigging on the original disclosed useability, care and performance of my car? It leaves me feeling no goodwill in return.

Nissan's latest claims only dig a bigger hole and prove to me that they are committing major fraud by selling these cars without disclosing these items. I do not have patience when pertinent buying information is being withheld from consumers trying to make a buying decision, and from reporters trying to accurately report on a product to its readers.

What will Nissan do? I am unsure. But I can tell you what charactoristics Nissan USA needs immediately: honesty, proactivness and integrity. Actions (words too) with these characteristics will get you much further than hiding behind lawyers and pr teams.

Thought - Now that i have read Nissan's latest comments, as a leaf owner i cannot drive on freeways and cannot drive 12500 miles in a year if i want the usability and life nissan already promised up front. What is next, will i not be able to use my headlights at night?!

Nissan's pre-sale lack of disclosure and post-sale re-nigging of vehicle useability is shameful. The desert region(Phoenix) leaf owners are the first affected, and are bearing a load of pain caused by Nissan. Please stand behind us.

Tim H. (not verified)    September 23, 2012 - 1:04PM

Just a polite reminder that the plural of most English nouns is indicated by adding an 's' to the word, such as, "Leafs."

In this article, the author has added an apostrophe before the 's' as well, resulting in "Leaf's" as the plural form. But the construction "Leaf's" indicates the possessive rather than the plural form, suggesting a property or feature of the Leaf, as in, "the Leaf's range varies..."

One pointed, and commonly misunderstood, exception to the rule is the construction of the possessive form of the pronoun "it." The general rule is the exact opposite of the rule in this special case: the proper possessive of "it" is "its" without an apostrophe, in order to distinguish it from the contraction of the phrase "it is." Thus, "it's not always understood that the possesive form of 'it' should be spelled 'its'."

Published text always has more credibility when it adheres to correct and accepted grammar, spelling, punctuation and usage.

Again, just a courteous reminder.

Chris Lynt (not verified)    September 23, 2012 - 8:28PM

In reply to by Tim H. (not verified)

Since LEAF is an acronym in this case for "Leading, Environmentally-friendly, Affordable Family car," a proper way to indicate a plurality of them is with an appostrophy. The word 'leaf' as in a tree leaf has as the plural "leaves" not "leafs" although in modern usage "leafs" seems to have crept in.

Jpwhite (not verified)    September 23, 2012 - 1:11PM

Claiming high mileage doesn't hold water with me. Steve Marsh in the Pacific NW is putting 40,000+ miles per year on his leaf and has experienced minimal battery deterioration, certainly nothing like what is being reported in Arizona.

If Nissan told me high miles In a hot climate is bad but elsewhere not so much, I'll be willing to swallow that one.

The biggest factor that appears to be in force is the desert heat.

I drive 13,000 miles a year so should see results close to the losses expected. But I don't know what to expect! Is Nashville average, above average or below average climate for battery degradation. We now know those in Arizona can expect an additional 4% loss over 5 years according to Nissan. Less than 1% per year sounds 'normal' to me. Shame that the reports and tests don't support this normality. I wouldn't be suprised to see Nissan revising these estimates as years roll by.

Anonymous (not verified)    October 16, 2012 - 12:55AM

In reply to by Jpwhite (not verified)

I bought my car late in April 2011, I put almost 25,000 miles on my car, and I have not noted any change in my battery. This car savas me a lot of money especially with the high gas price in San Diego.

Chris Lynt (not verified)    September 23, 2012 - 8:02PM

If there really IS any unusual 'capacity' loss in these vehicles, as their owners believe, the ONLY way to know for sure is to remove a suspect battery pack and bench test it by fully charging it, then discharging it through a known load while periodically measuring the power dissipated, the sum being the capacity in kWhrs - that's what a professional grade watt-hour meter does, in essence. This is the MOST accurate way to measure battery capacity. I know this because I am an electrical engineer. So far no one has done this, have they? No, what both Nissan and the testers are relying on is data coming from the vehicles in question, which could be faulty. The range test fails because if the Leaf detects faulty data it will go into 'turtle mode' prematurely - the driver will never know that there COULD be significant unused capacity. Recently, some Leaf owners experienced charger failure with the GE WattStation - the fault turned out to be in the Leaf on-board charger which failed when there was a brown-out condition during a charging cycle (a power surge could possibly cause the same issue). I suppose Phoenix and other hot area probably experience brown-outs, so these Leaf's in question may have had a failure of some component in the charging or sensing circuitry. Such a failure could result in a misreading of battery terminal voltage level (which as I understand it the Leaf uses along with a Hall-effect current measurement, despite inherent inaccuracies, for capacity calculations) which in turn could result in the loss of bars reported, or even, worst case, an overcharging of the battery pack and resulting damaged cells. There is an old expression - garbage in garbage out - so relying on the Leaf's data output derived from sensed terminal voltage, when the sensors could be at fault, is NOT definitive. Heat affects all sorts of electrical components - copper wire resistance goes up with temperature for example. Undetected errors could also be present in the firmware - perhaps if the calculations use a temperature measurement, then the hot climates could cause some glitch to appear in the calculations. I think the folks in AZ have jumped to the conclusion that it has to be heat damage to the battery pack, perhaps spurred on by comments by certain Nissan competitors? Rigorous controlled testing of the Leaf's in question down to the circuit level should be performed before any conclusion is reached. As a fellow-Leaf owner, I look forward to that. In the meantime, Nissan should settle with the few disgruntled Leaf owners out there.

Diane (not verified)    September 24, 2012 - 2:50AM

As a electric car advocate, this is troubling news. I expected Nissan to work with the early adopters if problems occurred and it appears that in all cases this is not happening. I Planned to write an article about the new Nissan leaf 2013 and be a cheerleader for it. I will put my Pom poms away for now and wait to see how Nissan responds. Please Nissan get your act together and do the right thing!

Anonymous (not verified)    September 24, 2012 - 5:35AM

In reply to by Diane (not verified)

Nissan gambled and loss on the Leaf...Three years from now most of those cars in heat related areas will see a 50% drop in battery capacity..
Nissan needs to add cooling to the battery packs to make the car more reliable..

I hope the Leaf owners take Nissan to court over this...

Anonymous (not verified)    September 24, 2012 - 9:51AM

In reply to by Anonymous (not verified)

It's probably not real degredation, it's probably a SW problem.

I'm guessing Nissan can issue a SW Patch and get a quick fix out in the field.

SOC / SOH algorithms are inherently difficult, and it sounds like @ high temperatures, high usages, Nissan did not do a very good job of characterizing the battery.

Tim H. (not verified)    September 24, 2012 - 11:52AM

Mr. Lynt is mistaken in his belief that acronyms are subject to different rules than other English-language nouns. As explained here - from the web site - that is not the case:

"You make the plural and the possessive in the usual way for acronyms. For example: I had a VCR. The VCR's power button was broken. I bought another VCR, so I had two VCRs. Then the second one's channel selector button broke, so I could tell that the VCRs' buttons were made cheaply."

In that Mr. Lynt has not taken even minimal care to avoid a preposterous, if amusing, misspelling of the word 'apostrophe' in his post ("appostrophy"), his credibility on such topics is open to expansive question.

One further point: the Nissan corporation, which invented the LEAF acronym, has explicitly advised that the plural of LEAF is LEAFS, not LEAVES. As Nissan contrived the construction originally, it seems fitting that Nissan is entitled to specify its plural form.

David Herron    September 24, 2012 - 12:57PM

In reply to by Tim H. (not verified)

LEAF is also a trademark name. Trademark names do not follow this normal grammar rule, and are supposed to be left unchanged when pluralized. At least that's how I understand it, having taken a small amount of training on trademarks.

Gregory Fung (not verified)    October 1, 2012 - 2:22AM

As an engineer who understand that real technical issues that exists, the is what happens when you need to simplify a not completely straightforward message to 5 words. This is what happens when you make assumptions and estimates of usage patterns, to be able to give a really simple headline of 80% in 5 years. And 76% instead of 80% with dramatically different usage is totally reasonable. If I was leading the Leaf program, I would have pushed for different assumtions and expectations to be clearly relayed to dealers and regional advertising for specific markets where the cars would be stressed. But of course these departments and structures have never dealt with anything like that, although I bet they do regional pricing and promotions quite well.

But I also understand the pressure of marketing communications to get the message across in the best light possible. I don't blame marketing completly: the user has to really understand what they can expect. Perhaps the sales process did not include a realistic explaination, or consumers actually glanced over the assumptions that do not apply to their use.

Here I blame the impatient, disengaged culture around our consumerist society. If there was patience and good communcation all around, there would be fewer unhappy owners