Skip to main content

Nissan Leaf owners stage massive test to prove battery aging case

To protest Nissan's lack of meaningful response to battery lifespan issues, Leaf owners in Arizona have banded together in one of the largest EV tests of its kind to prove that the Leaf's batteries are, indeed, aging prematurely and losing effectiveness before their time.

During the heat of summer, Leaf owners in hot climates - specifically in Arizona - began complaining that their cars were no longer retaining their 12 battery bars and instead were only allowing charge to 10 or 11 of them. Nissan says the Leaf's batteries are good for at least 7 years at up to 80% capacity, but at losses like these owners were seeing, that would mean far worse than that and in much less time.

Soon after the reports began proliferating both online and through dealership complaints, Nissan issued a statement saying they'd be investigating the issue and would make things right. So far, no further substantial information has been given by Nissan despite having called many of the affected owners into dealerships to do full diagnostic computer and systems downloads from their cars.

Tired of waiting and discouraged by statements in the media from Nissan representatives suggesting that the Nissan Leaf's batteries are "just fine," Leaf owners in Arizona and surrounds banded together to prove them wrong and show that there is, indeed, a serious problem that requires attention.

Twelve Leaf owners assembled in the evening at a parking lot in Arizona, lead by the infamous Tony Williams (who did a Canada to Mexico Leaf EV drive). Odometer readings from their cars ranged from 2,500 miles up to 29,000 miles. The location in Tempe, Arizona was chosen because it offers two J1772-2009 EVSE charging stations and a DC Chademo fast charger. This allowed the participants to easily recharge their cars before and after testing.

All vehicles assembled were fully charged and sent, one by one, out onto the streets of Tempe to drive a mapped route until their batteries literally ran out of juice. Because the driving was at night, free access to the chargers plus easy access to supporting fleets (a tow truck and some electric dollies) for retrieving the discharged vehicles was had. Measurements of total charge, expected range, and final ranges were all taken. Many of those involved are engineers.

The newest of the cars, those with the lowest mileage, lasted about 80 miles on average. Older cars, however, and those claimed to have suffered battery degradation were doing far less than that with one only getting 59.3 miles out of a full charge.

Full details and complete findings from the tests have been compiled and posted to Their case is well-proven and should put Nissan on notice.

One of the biggest engineering flaws in the Leaf, some in the industry have pointed out, is the lack of thermal management for the batteries. In temperature extremes, this could easily lead to the kinds of problems these Leaf owners in Arizona and now California are experiencing.


CHLPatent (not verified)    September 21, 2012 - 9:42PM

I'd hardly call 12 Leaf's a 'massive test' - seems to be a bit of a sensational headline? I believe Nissan will correct the problem, but it will take time to figure out exactly what is going on. It may turn out NOT to be over-heating in battery packs as many people have jumped to conclude. Instead, it could be some over-charging damage, perhaps because on-board circuitry behaves differently at extreme temperatures? Perhaps Phoenix experiences brown-outs which might play havoc with chargers? Any engineer can tell you that heat is a processor's worst enemy. Copper wire resistance increases with temperature and resistance might be a parameter used in charging calculations? Remember how one of the Mars missions almost went astray because some circuits were using metric and others English measurements? The Leaf is a high-tech machine, so finding the problem may take some time. While that may be little solace, I think some patience is in order. In the mean time, I think Nissan should step-up their response soon to head-off a PR problem.

Aaron Turpen    September 22, 2012 - 2:27AM

In reply to by CHLPatent (not verified)

Considering there have only been 14,000 units sold in the U.S. and Arizona is only one of several non-primary markets for the car (most sales are in California), 12 vehicles at one time is a big deal.

Second, Nissan has not only not answered the question of the battery problem, for which they've had several months to do so, but they've had representatives say that there is no problem.

I think, at the very least, Nissan should offer battery replacements to those affected as a gesture of good faith. Everyone I've talked to in the EV industry thinks that the lack of thermal management for the Leaf's batteries is a huge engineering oversight.

Russ Finley (not verified)    September 27, 2012 - 8:27PM

In reply to by Aaron Turpen

Roughly 40,000 Leafs have been sold. The Leafs in Arizona represent about 10% of all Leafs. If ten percent of them need recompense, that would be about 1% of all Leafs. Why would Nissan saddle 99% of its Leafs with the cost, complexity, and energy draw of a coolant system when they don't need it?

Aaron Turpen    September 27, 2012 - 9:24PM

In reply to by Russ Finley (not verified)

Not sure where you're getting your numbers from. The latest is about 14,000 in the U.S.

How abut this reason: the Ford Focus Electric is heavier, larger, and has a smaller battery pack, but has a longer range than the Leaf. Ford attributes this completely to the battery's thermal management system. Reason enough for ya?

The problem is now cropping up in California and may be happening elsewhere, for all we know. The car hasn't been on the national market for much more than a year (nationwide sales began about this time last year).

Every other EV of merit has thermal management for the battery. Coda has one, Tesla has one, the RAV4 EV has one.. they're there for a reason.

Russ Finley (not verified)    September 27, 2012 - 10:50PM

In reply to by Aaron Turpen

Why would you limit yourself to just the Leafs in the U.S. instead of the world? Seems a little myopic.

Ford Focus:

Base MSRP: $40,000
Body type: Sedan
Range: 76 miles
Battery size: 23 kWh
Charging rate: 6.6 kW

An extra $5K for a thermal management system I don't need? Pass ...The Nissan Engineers know how the battery will perform without thermal management. 99% of the cars won't have a problem. Nissan will have to replace or buy back some cars in really hot places. The Volt recalled 8,000 cars.


Aaron Turpen    September 27, 2012 - 10:55PM

In reply to by Russ Finley (not verified)

Because the Leafs in the U.S. are the ones we have data for. That's why I chose that "myopic" view. If Nissan published unaltered raw data on their vehicles, sales, performance, problems, etc. then we'd use those. Like every other car manufacturer, though, they don't. It's why focus on the Volt is entirely American, despite there being Volt copies in other countries as well.

The Ford Focus Electric costs more because it's larger. It's not in the same vehicle class as the Leaf. You also ignored my last statement. EVERY OTHER EV HAS THERMAL MANAGEMENT.

You can be pro-Leaf if you want to. That's great. I don't dislike the car. I do, however, admit it has limitations and engineering woes. Just like the Karma. Just like the Roadster. Just like the S. Just like the Volt.

jstack6 (not verified)    October 10, 2012 - 6:04PM

In reply to by Aaron Turpen

My LEAF has lost 20% capacity, I only charged to 80% the entire 1st year. I always park in the shade, I never Fast Charged even once, I drive very conservativly getting 5.6 miles per Kw. Yet my pack and every of the 100 out of 450 in AZ we have checked have lost 10-30% .

It's a major flaw not to control the heat and cold in a pack.
Why did they include the battery heater , seat warmer and steering wheel heat in all 2013 and never LEAFS. so anyone can own and drive anyplace.
They also should have included at least FAN air cooling of the batteries. They told us don't worry they will be fine. But they aren't .

Anonymous (not verified)    September 23, 2012 - 5:27PM

In reply to by CHLPatent (not verified)

The Mars mission didn't "almost go astray". It slammed into the surface of the planet! As for overcharging? I doubt it. When Lithium batteries are overcharged they don't react well. They catch fire. I've thought undercharging might be a cause, since that does decrease capacity, but it appears none of the drivers take the battery to empty (and Nissan doesn't let the voltage go low enough to cause damage).

That leaves overheating as the most-likely culprit especially if Nissan is right and most of the miles are highway miles (high current == high heat generation).