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Nissan says greater than average battery capacity loss due to mileage and temperature

23 September 2012

Nissan Senior Vice President, Research & Development–Nissan Americas, Carla Bailo sent an open letter to the LEAF community summarizing the company’s initial findings on reports of battery capacity loss expressed by a number of owners in the Phoenix market. (Earlier post.)

Bailo said that Nissan identified seven LEAF owners in the Phoenix area who had reported concerns with their vehicles. Nissan brought the cars to its Arizona test facility, removed the batteries for evaluation, measured capacity, and conducted voltage testing on individual battery cells. These tests were diagnostic only; no modifications were performed to the battery packs themselves.

Nissan then analyzed the results with specific emphasis on the rate of actual capacity loss for each vehicle. The goals of the testing were to determine:

  1. if there were any defects in materials or workmanship in the individual batteries or vehicle systems;

  2. if the batteries were performing to specification; and

  3. their performance relative to the global LEAF population.

Overall findings were:

  • The Nissan LEAFs inspected in Arizona are operating to specification and their battery capacity loss over time is consistent with their usage and operating environment. No battery defects were found.

  • A small number of Nissan LEAF owners in Arizona are experiencing a greater than average battery capacity loss due to their unique usage cycle, which includes operating mileages that are higher than average in a high-temperature environment over a short period of time.

While we understand that some LEAF owners are concerned about battery capacity loss, we want all owners to remember that all battery-electric vehicles—and all lithium-ion batteries—demonstrate capacity loss over time. So while your LEAF may have been able to travel a certain distance or more on a charge when new, its range will decrease as the battery ages, miles accumulate and gradual capacity loss occurs. This loss in capacity will occur most rapidly in the early part of your battery’s life, but the rate should decrease over time.

...It is also important to put the scope of these concerns in perspective. Globally, there are more than 38,000 Nissan LEAFs on the road that have travelled more than 100 million zero-emission miles, and we expect these vehicles, in normal operating conditions, to retain 80 percent of battery capacity after five years. As each user’s operating characteristics are unique and many factors impact battery capacity, we can expect some vehicles to have greater than 80 percent capacity at five years, and some vehicles to have less.

In Arizona, we have approximately 450 LEAFs on the road. Based on actual vehicle data, we project the average vehicle in that market to have battery capacity of 76 percent after five years—or a few percentage points lower than the global estimate. Some vehicles in Arizona will be above this average, and some below. Factors that may account for this differential include extreme heat, high speed, high annual mileage and charging method and frequency of the Nissan LEAFs in the Phoenix market.

September 23, 2012 in Brief | Permalink | Comments (29) | TrackBack (0)

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80% after FIVE years?
I thought that was supposed to be after 8-10 years?

In that case the Leaf is not an economic proposition anywhere else, let alone in Arizona.

It depends how many miles they cover in those 5 years, no?

EP:
They are talking about 80% as an average, so it will be based on average mileage.

The Leaf car is not a viable proposition if you need a $10,000 or so replacement battery after 5 years.

It also means that a lot of people will get below average, those in Arizona for instance.

How bad a deal is that?

At trade in your car will be worth buttons.

Arizona is a special case for temperature and distance.  The SF bay area would probably stress batteries a lot less.

It is not the 75% remaining capacity in Arizona after 5 years that kills the Leaf, although it of course makes it absurd to buy one there, but the 80% average remaining capacity after 5 years.

What is your car going to be worth when you want to trade it in after 3-5 years?
It makes no economic sense at all.

Nissan may have to modify the battery thermal management system, specially for LEAFs operating in very hot areas like Arizona and for users who require higher speed for longer distances. At least, it should be a recommended option? A liquid cooled system may be required?

There are different trade-offs and flexibilities with EVs. The motor may not need to be replaced in a million miles or decades. The five year fuel/maintenance savings may more than buy a better cheaper future battery.

Perhaps a future genset can mount via a trailer hitch(patent pending:).

VW made MANY sales/ads off of longevity. I still recall Woody Allen finding a VW bug in a cave, dusting it off, and driving it off in a movie.

Maybe EV ads should leverage this.


There are different trade-offs and flexibilities with EVs. The motor may not need to be replaced in a million miles or decades. The five year fuel/maintenance savings may more than buy a better cheaper future battery.

Perhaps a future genset can mount via a trailer hitch(patent pending:).

VW made MANY sales/ads off of longevity. I still recall Woody Allen finding a VW bug in a cave, dusting it off, and driving it off in a movie.

Maybe EV ads should leverage this.


Davemart,

AFAIK It has always been 80% after 5 years, 70% after 10 years.

The other reasons given by Nissan seem standard corporate YMMV speak, as the owners at mynissanleaf.com have not been able to identify any correlation with speed, charging habits and only a weak correlation with mileage. Persistent high average ambient temps is what kills the battery, the other factors just come in handy for Nissan to prop up their press releases and divert attention. Expect a class action suit soon.

Harvey

Nissan may have to modify the battery thermal management system,

What thermal management system?

Perhaps I misunderstood what Nissan were claiming on battery life in the past, but in any case 5 years to 80% is not economically viable.
I make that a range on the EPA cycle of under 60 miles.

Nissan simply have the wrong battery chemistry.
Some varieties of NMC, lithium ion phosphate and lithium titanate all have much, much better cycle life.

To come extent the decay in hot climates can be delayed by liquid cooling, but that does not solve the problem when you are parked in the heat for the day, although it mitigates it.
GM, which uses a similar chemistry in the Volt, not only has liquid cooling but has specified the DOD very conservatively to give acceptable life.

Here is A123's new lithium ion performance:
'Just to repeat, that is 167 degrees Fahrenheit they are testing these pack ats; hotter than any recorded temperature on Earth. And under these extreme condition, after 700 full cycles, the pack is still retaining 90% of life.

In “LEAF miles” that would be 90% retention after 50,400 clicks, in 167 degree weather.'

http://insideevs.com/a123-updates-next-gen-nanophosphate-ext-batteries-solves-lithium-battery-heat-issues/

@DaveMart:

You have conflated two completely different propositions and your logic is weak at best.
If it has only 80% battery capacity after 5 years
"In that case the Leaf isn't an economic proposition to anybody" AND "you have to replace your battery after five years".

Who says? If your leaf still covers your commute then it's still an economic proposition. Same answer to your battery replacement bullcrap.

Also it's worth pointing out that even in a gasoline powered car the gas mileage deteriorates over time but nobody uses that as an excuse to replace the engine.

Please try to do better with your logic.

I'm not sure what your problem is, or why you feel the need to address other posters aggressively.

I can't be bothered to reply to your snotty ignorance.

Your notion that people will buy the car in any volume if the battery deteriorates at that rate is as ill-conceived as your manners.

Xxdanbrowne,

Welcome to greencarcongress.

As for your notion that gas mileage deteriorates over time, this is much less of an issue for modern cars, and usually only occurs if the car gets really old.

The second thing you do not account for is that a lower mileage is easier to compensate than short range. The LEAF is already at the low end of usable range, so any deterioration quickly renders the car useless for its owner.

In hot regions, use more sturdy battery chemistry, and use PHEV's with 10-20-mile AER, instead of BEV, charge the car twice a day, and replace the battery every 5 years or so, before significant calendar life loss. If driving only 10-mile each way of commute, then get the Prius Plug-in for 11-mile AER, and charge twice daily. If driving up to 20 miles each way, then get the Ford C-max Energi and charge twice daily.

H2-FCV is another potential consideration for ZEV selection in regions of extreme climate (too cold or too hot) after 2015.

@Roger:
There is no need to accept a five year battery life in any region.
There are several chemistries which have far higher cycle life, which in turn means that it is not so disastrous if you have to sacrifice some in hot climates.

Mercedes's Li-tec, for instance, is rated for 400,000 km, which is about 250,000 miles, as against 100,000 for the Leaf, so that gives lots of leeway whilst still having a reasonable life.
Since if you option to buy the battery instead of lease it costs you $284kw, it is hardly expensive.

If Nissan are saying that in five years of average use the battery will be down to 80% their claim that you can get around 100,000 miles out of a pack seems absurd, since they sure aren't saying 20,000 miles a year is average.
Averages are usually calculated on the basis of 12,000 miles a year.
So perhaps Nissan is now saying that 60,000 miles down to 80% is what you can expect.

As far as I recollect, Nissan were talking about 8-10 years and 100,000 miles down to 80% without fast charging, or 70% with fast charging, which would be acceptable.

I think Nissan have been caught out, just as they have in the sales numbers they expected.

I also remember Nissan talking about an NMC chemistry, with higher energy density.
Some variants of this also have higher cycle life.

In my view they need to urgently change to a different and more robust chemistry.

Yes, Nissan next generation BEVs will probably have more robust batteries + improved temperature management system (liquid + passive cooling etc?). A cold weather pack already exist (as an option) and a hot weather pack will soon be available (as an option)?

Remember, the fist generation ICEVs were not perfect and had 1001 problems.

Not only has Nissan been caught out but the whole crack pot idea of electric vehicles using lithium ion batteries that don't have the range and need battery replacement to the tune of $10large after 5 years of driving is called into question.

Mannstein, not all lithium batteries are the same. It is easy to generalise, but this history is far from over.

“greater than average battery capacity loss [battery is defective but they say its] due to their unique usage cycle, which includes operating mileages that are higher than average…”
Unique and higher than average? The EPA says annual estimate of cost is $561 based on a 15,000 mile year, i.e. average which I seriously doubt most of them exceeded. Also average? VOLT loves to say the average driver goes less than 20 miles a day… is this what they mean?
“…. in a high-temperature environment”
Meaning Arizona is too hot to use these cars as it wasn’t designed to be fit for use there as these customers intended to use the car as a daily commuting car.
Ergo
1. the 35K Nissan Leaf is about a useful as a bloated in-City only grocery vehicle (i.e. golf cart).
2. The manufacturer warranty is a farce as it never warranted the battery operating at its advertised range on the EPA sticker. They ought to include the “normal” range decrease then as well.

So far, there is a rumor the replacement battery cost for a Leaf is $5k, including a core charge of course.

Per Nissan data the average Leaf commute is 29 miles so there is plenty of room for battery degradation, sprinkle in a few chargers around town and you can stretch the range of your old Leaf.

Where did the rumour come from?
Have you just made it? :-)

'Though several LEAF owners have succeeded in selling their vehicles in the wake of overwhelming evidence that the car frequently experiences rapid battery degradation in warmer climates, others haven't been so lucky. Over the last two weeks I've spoken to several frustrated LEAF owners in the Phoenix area who have tried to no avail to sell or trade their cars back to the dealerships they bought them from. In some cases, dealerships told them that they are unwilling to purchase any used LEAFs because to date, Nissan has offered no assurance that the problem will be remedied.'

http://www.plugincars.com/arizona-leaf-owners-selling-no-longer-option-124510.html

Xxdanbrowne,

Get better manners or leave.

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