First Reports Of Leaf Battery Capacity Loss

Yep, you got the right MNL thread. We'd been keeping a running list in the thread of reported capacity (bar) loss since the OP hadn't been doing that at all. Recently, he suddenly decided to post a summary and a running list there too.

My Nissan Leaf Forum • View topic - Lost a "high-voltage battery status" bar, down to 11 is the latest running list I know of, at the moment.

It'll be very interesting to see what the list looks like at say the end of September 2012 and 2013, esp. for the folks in AZ and TX...

 

I wonder how this will pan out and how the knowledge gained could help the Prius community. We know that Prii batteries have a higher incidence of failure in hot climates. In one test, I think performed by 2009Prius, the act of using the AC too cool down the cabin on a hot day actually increased battery temperature. This makes sense since the AC pulls quite a bit of current when running at a high load (1500w?). This would cause the battery to heat up. If the trip is too short too allow the AC system to wind down and run at a reduced load and thus a cooler cabin temp then the act of running the AC vs. driving with the windows down could be very hard on the battery. So where does this leave us if true?

 

All I can conclude so far is that it seems like a bad idea to buy a Leaf in AZ and TX. Better to lease a Leaf or buy a EV/PHEV w/TMS (thermal management system). Thus, it might not be a great idea to buy a PiP in those states either.

From the chatter I skimmed of the event at My Nissan Leaf Forum • View topic - Event - REFUEL at Mazda Raceway Laguna Seca 07/01/12, it seems like the Leaf doesn't have battery heating issues when driving.

DC fast charging (quick charging, via CHAdeMO) can heat it up (other threads on that). We can so far deduce that the high sustained ambient temps like in AZ and TX cause capacity loss.

BTW, for those that don't know, the capacity loss is the loss of the very thin bar on the right side of File:1 bar capacity loss in 16k miles 7165397296 41cfcf8d33 b.jpg - MyNissanLeaf. The photo has bad focus, unfortunately.

Battery, Charging System - MyNissanLeaf is a table supposedly from the service manual.

 

Air cooling is less efficient than liquid cooling. There's a reason owners are told to keep batteries out of the sun. Air cooling may work at highway speeds but when the car stops so does the airflow over the hot battery. A cool battery is a happy battery.

 

I guess TX n AZ are the states to watch how Nissan treats warranty claims in a couple of years!

 

But there's no battery capacity warranty. From http://www.mynissanleaf.com/wiki/images/f/fe/2012-leaf-warranty-booklet.pdf:

There's been a lot of debate on MNL about what "gradual" means. It seems that owners who've experienced capacity loss (via loss of 1 or more capacity bars) have been blown off by dealers saying "it's normal".

You find find more of such debates/discussion by Googling for site:mynissanleaf.com gradual capacity loss.

 

The leaves are falling?

 

Nissan will have a class action lawsuit on their hands regardless of the legalese they employ if this becomes a serious issue. The "100 miles range" nonsense was bad enough, but the skirting responsibility will certainly bite them back. And it doesn't matter that some owners express such sentiments as "well, I bought this car knowing the potential pitfalls of being an early adopter". The problem is that "gradual" capacity loss and "80% after 5 years" affected potential buyers' decisions. There was no mention of "only in specific environments" or that that 20% loss could happen in the first year of ownership. If Nissan had stated that these cars could reasonably be expected to get no more than 60 miles per charge if you happen to do any freeway driving in a warmer environment like Texas or Arizona, I would bet good money that demand would have been seriously hampered.

 

We know that an initial rapid loss in capacity is expected, so the one bar loss may be partly a calibration problem. Year #2 and beyond will be *very* informative.

LEAF owners (and everybody else with a traction battery in their cars, to a lesser extent) will be wise to learn the do's and don'ts of prolonging battery health:

DO NOT draw down to minimum
DO NOT charge to maximum if the car is going to sit when charging is complete.
BE very careful about charging in direct sunlight, or with windows closed.
GIVE thought to helping the battery keep itself cool.

This issue reminds me of the Tesla mix-up not too long ago after an owner bricked his battery by letting it self-discharge too far. These are new technologies, and owners had best be ready to learn and adapt to smooth the rough edges.

Or enrich the lawyers. Their choice.

 

yep same lesson(s) . . . . run hot (110+ degrees) - charge hot - charge to full then let it sit for weeks & weeks, etc . . . all the things they say not to do - and (go figure) your capacity will shorten sooner than expected. Or maybe one could say capacity will shorten accordingly.

 

Most folks treat their cars as "fire and forget" devices. "Maintenance" is when a dash light comes on to take it to the dealer. It's an unfortunate reality that any manufacturer's recommendations/requirements for operation and storage are going to be ignored by many. For electric cars to succeed, they must have the protections built into the car, not the manual.

 

What's nice about the leaf is that at least it has a gauge that lets the owner know he has actual capacity loss. SO - the Leaf owners know they got what they got. The Volt does not have a gauge showing loss. Since both cars came out at the same time (over a year ago) - it will be interesting to see what kind of capacity loss may be going on with extreme heat area Volt owners . . . . or, with no gauge - whether or not owner's capacity is readily even detectable.

SGH-I717R ? 2

 

Precisely. The issue is not a "maintenance" issue, but rather a vehicle that was sold for use in environments that have proven hostile to basic function. This is about a manufacturer employing legalese to paint over a product's shortcomings.

 

Nissan needs to cover these cars under warranty or it will greatly hurt leaf sales. If they do its more of a we didn't know, we are making it work, which is good for the reputation. Otherwise if they pull a honda, sales will suffer.

As to letting you know the design didn't work, I would rather have something that works than good indication that it is failing. Volt owners do have indications that range is falling. The car generates reports. But, the volt will not allow you to fully charge it, which means the BMS can play with the SOC, and give you the range even if capacity is falling. It makes sense to do this, but owners will not know its happening until much later, but they also won't be effected until much later.

Volts were being sold in texas before the leaf. There should be more data. I would trust the volt or tesla much more than the uncondtioned leaf or prius phv in the texas heat. This may be one reason toyota is not selling the phv here, even though it would be a good market. They may be heat testing the battery packs longer before they sell them in my state.

 

AC set to 75°f on a 90°f day only uses only about .8kW - 1.5kW. It's only the heater usage that blows range out of the water. Nissan's already addressed the large climate power draw of the heater by installing seat heaters. That's the great trade off when the public is screaming, "WHERE'S MY EV!!". Buyers want it now ... then have regrets if/when short R&D causes disappointment's. Hindsight is 20/20.

....agreed - especially because when the Volt pack gets low (think Civic hybrid snafu - traction pack capacity loss) - the ICE then has to compensate for any shortfall. That would cause a Volt's over-all CS mode range/mpg to take a huge hit because you'd be carrying around a heavy/depleted pack more frequently. On the bright/hopeful side - it may be Volt's over-engineered (liquid cooled) BMS may become a saving grace ... perhaps enabling it to better survive blisteringly hot temps.

.

 

What hindsight ? I have been telling you guys for years that winter is a bitch on EV range, and I am hardly the only person. Don't blame "the public" because some are deaf and blind.

You have reminded me of the idiots who refused to understand that a hy*EV is a combined heat and power plant in the winter, while an EV never is so far as the car is concerned, and only rarely at the level of the power plant.

 

While the LEAF battery failure situation is very narrowly focused, it has implications for everyone who has lithium-ion batteries in their vehicles. That includes some Prii, but there is something to be learned for just about all of us.

The situation is narrowly focused -- for now at least -- because it involves a single brand of car, the LEAF,;a single lithium-ion chemistry, IIRC lithium-manganese , LiMn2o4?; with a simple Temperature Management System, air, only when the car is charging or operating; and a limited geographic area, AZ, or more properly Phoenix.

LEAFs there, essentially all of the MyNissanLeaf owners in Phoenix, have seen a significant and they believe accelerated loss of HV battery capacity. The loss appears to be independent of all operation variables: battery charging, miles accumulated, car color, etc. Apparently the only common condition is just being in the extended, routinely in excess of 100 degF, summer temps in Phoenix. Owners have seen capacity losses of up to 20%, with a few saying that another 6% hit is only a matter of time, and that very short as the REAL summer temps are only just beginning.

The heat is baking the capacity out of the HV batteries. And there's nothing that can be done. Charging times, charger type, voltage are all irrelevant. Right now, LEAF owners in Phoenix are in what I'd call a "capacity preservation" mode. This consists of daily charging only enough to meet that days needs - charging to 100% is not recommended high heat or no, charging at the coolest part of the day -- but even overnight the ambient temp often doesn't go below 85 degF, centering charge around 50% -- which results in more frequent L2 charging at public chargers. They're not looking for extended range per se, they're looking to minimize the amount of charge delta at any single charging.

There is a very small chance that the capacity reduction is the result of a pre-programmed Battery Management System strategy to protect the HV battery. And maybe, just maybe there's a l-o-n-g, outside chance that some capacity will be regained in cooler weather… in the fall, 3 long, hot months in the future.

The Interesting thing is the LEAF folks can measure their HV battery capacity every time they charge up. Some knew, or suspected, that something was happening long before the community as a whole accepted it. We can't say that.

The simplest lesson learned is, thermally speaking, treat your HV battery with kid gloves… no matter what battery chemistry you have. Keep it cool. If the heat bothers you, it bothers your HV battery too. You my be able to retreat to a pre-cooled house at the end of your trip, but your car/HV battery will continue to cook, long into the night in some cases.

Park in the shade, use windshield/rear hatch sun shades. If possible, leave windows open an inch or two.The HV battery is cooled with cabin air. On hot days forget max MPGs, use the air cond, you'll fell better, and you battery won't be stressed. If the HV battery fan comes on before the air cond, you screwed up.

A relevant read: Warranty Implications For BEV And Start-Stop Vehicles - DMF81 - Seeking Alpha

(FWIW, even though I don't own a LEAF, I've been a member at MyNissanLEAF since Apr, 2010.)

 

If it helps reliability, its not over engineered. I would not put it in the civic book, until there is actually some negative data. They have been monitoring the cars, and have increased state of charge for 2013. Certainly a phev can use the ice to keep a battery in a better operational range when it is hot or cold. Tesla likely engineered their bms to even higher standards.