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Despite AZ Woes, Most Nissan Leaf Batteries Fine, Survey Shows

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Nissan Leaf: Lost Battery Capacity

Nissan Leaf: Lost Battery Capacity

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Last summer wasn't easy for Nissan or its electric car, the Leaf.

A spate of owners in Arizona discovered they were quickly losing battery capacity, far earlier than Nissan suggested it might happen--the hot climate was playing havoc with battery life.

Luckily for worried Leaf owners, those 'wilting Leafs' were the exception, rather than the rule. A new survey from Plug In America reveals that the majority of Leaf owners have lost very little capacity--if any.

Plug In America's independent Leaf battery survey collected data from 240 Leafs in 25 states, 2 Canadian provinces, and the UK. Cumulative mileage over the cars surveyed is almost 3.2 million miles.

While that's still a small proportion of total worldwide Leaf sales, the survey still provides an interesting insight into how quickly Leafs are losing capacity.

Most owners still at "twelve bars"

Generally, statistics coming from the report are positive.

There are 12 battery capacity bars shown on the Leaf's display, and almost 91 percent of those surveyed hadn't lost a single bar. Just over six percent have lost only one bar, the remaining owners down to ten bars.

In addition, over half of the owners think their total range is still about the same it was when new. A tenth of those questioned had lost over ten miles, with the remainder split between those who'd lost only a little, and those who'd lost between 5-10 miles--though 1.3 percent actually suspected range had increased!

Hot climate certainly plays a part in battery loss.

One owner, with just under 60,000 miles on the clock, hasn't lost a single capacity bar--though the car is only being driven in highs of between 75-80 degrees. Most of those who had lost capacity, on the other hand, have seen temperature highs of over 95. Seven owners over this point have lost two bars.

Further data gathered on the MyNissanLeaf forum, where some owners have lost as many as four bars, also backed up the temperature data. All the greatest losses were recorded by owners living where average high temperatures are around the 105 Fahrenheit mark.

Quick charging not a major factor

In contrast, there seems to be very little correlation between capacity loss and quick charging--many of those with lost bars have quick charged fewer than ten times, yet one owner with over 70 quick charges hasn't lost a single bar.

Battery health tests seem to back this up--most reporting a clean bill of health, regardless of the quick charging frequency.

Several other factors all proved fairly inconclusive as far as battery health is concerned.

As a result, it seems fairly clear--temperature is the number one factor in battery capacity loss. Those living in hotter climates are considerably more likely to lose capacity, regardless of mileage--yet it's quite possible for drivers in cooler climates to do quite high mileages before seeing any significant deterioration--contrary to Nissan's original presumptions on capacity loss.

While the data will be of little comfort to Leaf owners in hotter regions--save for Nissan buying some back under lemon laws--it should also be reassuring to those in cooler climates--and to those who regularly use quick charging stations.

For the full report and data tables, click the link to Plug In America's battery survey (.pdf file).

[Hat tip: Tom Saxton, Plug In America]

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Comments (7)
  1. for all those who participated in the survey, it is important that this be ongoing. report back every 3 months or so to update your information. This will allow a much better capability to predict what may happen down the road. This is invaluable information!
     
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  2. I wouldn't be so quick to wave off the challenges of driving a Leaf in cooler climes.

    In Chicago, my six-month-old Leaf is averaging about 36 miles to a charge—that's about a third of the EPA rating. The drop in performance that the disclosure materials described for temperatures in the teens really happens at around 50º, in my experience. This has been a mild winter, by Chicago standards, but still, the temperature is below 50º far more often than it is 18º.

    Nissan corporate insists that my car is in perfect working order, but 36 miles is just not acceptable in a vehicle without a gas backup. It certainly is not what I signed up for, especially without a home charging station. I want out.

    Not seeing much improvement in the 2013 edition.
     
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  3. That is different from battery capacity though.

    All cars get worse mileage in the cold. It is just more significant for BEVs since its efficiency is so high. Any use of energy (in this case, heat) will drain the battery quickly.

    Remember that your Leaf Battery Pack holds about 70% of the energy that a gallon of gas holds...
     
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  4. Dani,
    I have not delt with reduced capacity, however efficiency goes down as we all know and as Xiaolong Li mentioned. 36miles with blasting heat, seats, defoggers (front and rear) and in ECO mode with traffic is fairly decent. I preheat- use only seat warmers and pump the windsheild defogger for 1-2seconds here and there and I am still able to go 65miles (my commute is 70 therefor currently i swapped vehicles with wife for the winter) But our heat is not as efficent as we would like.
    No L2 at home is a big issue as you cant enjoy and rely on the car as a sole provider of transportation. Investing in a L2 or using a local public station may help.
    What is your heat usually set on? Try auto mode at 60 and coasting without braking and it may improve millage just a little bit.
     
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  5. Well, we all know that heat accelerate "aging". In this case, I think the excessive heat really accelerates the battery life degradation.
    I am surprised that Nissan didn't do this test in their R&D cycle.
    I think the survey percentage is "pointless". B/c most of the cusstomers are in the "cooler" climate. So, statistically speaking, this survey only means the car is ready for cooler climate, but NOT ready for hot climate.
    It should have surveyed all the Leaf owners in hot climate ONLY and see if there are signficant degradation.
     
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  6. The survey analysis (PDF linked above) actually does a great job at correlating degradation with a number of factors.

    On page 10 is a graph of degradation vs high average temps vs odometer. It combines the survey data and people having reported lost capacity bars on mynissanleaf.com, so it can't be used to gauge how prevalent the problem is, but highlight very well which conditions favor it.

    Something that should be noted however: all the above results rest on the crude capacity meter on the Leaf's dash, which sometimes can be quite inaccurate, as a large-scale range test in Phoenix has demonstrated.
    http://www.mynissanleaf.com/viewtopic.php?p=228326
     
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  7. Kudos to Tom Saxton! We exchanged emails in early October, and among other things, I wrote the following:

    I'm quite certain that these batteries are more temperature sensitive than we were led to believe. There is an overwhelming body of evidence building, and if nothing is done before next summer, it should be fairly easy to spot trends.

    It's becoming clear that any Phoenix Leaf with this type of mileage will have less than 75% of battery capacity remaining, which is typically considered to be end of life. Elevated ambient temperature exacerbates cycling losses dramatically for this battery, and higher mileage cars will be the first victims.

    Seattle and Portland will continue to do well. Arizona, Texas and Florida not so much.
     
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