Some Leaf Owners Experience Early Capacity Loss

[TonyWilliams]

As far as I can tell the most technically savvy on MNL are not even sure of the usable capacity in a LEAF.

Because it doesn't have a single value.

 

[GerryAZ]

How many people still think a thermal management system for the battery pack is unnecessary?

I am in Phoenix and I see no reason for the added complexity of active thermal management. My battery temperature has ranged between 4 and 8 bars during the past 11 months and 10,000+ miles.

Gerry

 

[RegGuheert]

How many people still think a thermal management system for the battery pack is unnecessary?

Until it's actually proven that temperature is the cause, or even a major contributing factor,...

According to this article, the lithium hexafluorophosphate in Li-ion batteries breaks down even at room temperatures and the effect accelerates as the temperature increases:

Leyden's battery replaces lithium hexafluorophosphate, one of the components of a lithium-ion battery, with imide salt. Unlike lithium hexafluorophosphate, it does not react with water inside the battery cell, a reaction that significantly degrades the cycle life of a battery. Lithium hexafluorophosphate also starts to decompose at room temperature and loses its effectiveness more significantly when the temperature hits 55 °C. Imide salt doesn't start to decompose at higher temperatures.

If the battery in the LEAF contains lithium hexafluorophosphate, and I'm betting it does, then temperature is a significant contributing factor. Does anyone know? (BTW, the battery Leyden Energy is developing looks like it might make a GREAT replacement for the current LEAF battery some day!)

...there is no reason to think thermal management would have prevented the problem. Jury is still out.
=Smidge=

I agree the jury is still out on the issue of thermal management systems, however. When it is 105 degrees F in Phoenix, do we expect the car to run a compressor to cool the battery below ambient temperatures. At some point, you just need a higher-temperature battery solution.

 

[Cheezmo]

When the Leaf is plugged into a level 2 charger, a motor comes on, I was told it is circulating coolant to cool the batteries. So, is there not some kind of thermal management system in place even if it is only when charging?

 

[Randy]

The pumps that come on during charging are to cool the battery charger (under the hump in the trunk). The battery itself is made up of modules that are in a sealed container under the car. No forced air or liquid cooling for the battery

 

[thankyouOB]

I have become really concerned in the past few days as my battery temp, which always used to be at 5 bars, is now occasionally at 6 bars after charging in the sun.


OK. that was a faux concern, to show that for every odd case, there are prolly hundreds (or more) where the is just no issue about battery life.
I dont want to say we dont want to know (canaries are useful); but i do want to remind that a few cases are just that--a few cases.
We need data, and it is too bad that Nissan is not sharing.

 

[TonyWilliams]

When it is 105 degrees F in Phoenix, do we expect the car to run a compressor to cool the battery below ambient temperatures.

105F would be ambient in your example.

 

[TonyWilliams]

How many people still think a thermal management system for the battery pack is unnecessary?

I am in Phoenix and I see no reason for the added complexity of active thermal management. My battery temperature has ranged between 4 and 8 bars during the past 11 months and 10,000+ miles.

Gerry

So, to you, 26F to 126F is "good" for the battery ?

 

[Herm]

I have become really concerned in the past few days as my battery temp, which always used to be at 5 bars, is now occasionally at 6 bars after charging in the sun.

Why did Nissan make that temperature gage so prominent?.. makes ya think. I hope Engineer provides an actual temp readout in his new device.

 

[RegGuheert]

When it is 105 degrees F in Phoenix, do we expect the car to run a compressor to cool the battery below ambient temperatures.

105F would be ambient in your example.

Yes, and a LEAF battery soaking at 105F in the shade would approach 105F. That is likely hotter than the current technology will withstand for long considering Nissan says no more than 24 hours at 120F. If soaking in the sun at those temperatures, the battery could get well above 105F.

Regardless, my point stands as written. I don't think having to run a compressor to be able to cool a battery makes much sense. Better to apply a high-temperature battery technology. They exist now with higher capacity.

 

[Smidge204]

Regardless, my point stands as written. I don't think having to run a compressor to be able to cool a battery makes much sense. Better to apply a high-temperature battery technology. They exist now with higher capacity.

Unless, of course, the cost, weight, energy and power density of the high-temp technology were such that it's easier and better to actively cool the pack. Everything is a tradeoff...
=Smidge=

 

[RegGuheert]

Regardless, my point stands as written. I don't think having to run a compressor to be able to cool a battery makes much sense. Better to apply a high-temperature battery technology. They exist now with higher capacity.

Unless, of course, the cost, weight, energy and power density of the high-temp technology were such that it's easier and better to actively cool the pack. Everything is a tradeoff...
=Smidge=

It's not weight or energy density, since those are shown. Manufacturing cost appears decent since it can be manufactured on standard equipment. Licensing cost could be an issue. I suspect you are right on about power density, since I can find absolutely NO mention of it on the website and there is a mention of "light" electric vehicles.

Still, this will be one to watch since temperature appears to be an issue that will impact some EV owners and capacity impacts us all.

 

[TRONZ]

I think it would be helpful if Nissan started to provide more (any?) guidance on their future battery technology. This is the whole ball of wax on investing in an EV and is very competitive information, but that is also why investors are given guidance on big issues from time to time. Without getting into specific specs/prices, if Nissan simply declared that future EV battery modules will be designed to also retrofit into LEAF, everyone's confidence would be bolstered. We all have it in the back of our minds and yes its an over the horizon issue but it would be a very easy way for Nissan to futureproof any of the LEAFs battery worries.

In 18 months a lot of the early lease holders will be making a decision about keeping their cars. Car companies usually want to roll you into a new lease so I expect a lot of official LE offers arriving in our mailbox around then. But a pampered $16K hatchback EV will be a real keeper if you were also guaranteed reasonably priced and "better" batteries whenever you decide you want them.

 

[LEAFfan]

How many people still think a thermal management system for the battery pack is unnecessary?

Until it's actually proven that temperature is the cause, or even a major contributing factor, there is no reason to think thermal management would have prevented the problem. Jury is still out.
=Smidge=

+1!

 

[TRONZ]

As far as I can tell the most technically savvy on MNL are not even sure of the usable capacity in a LEAF.

Because it doesn't have a single value.

Yes. It is surely very difficult to shoot at a moving target. Which also leads me to a question.

If a LEAF charging overnight on a cooled pack is also finishing its charging during the coolest part of early morning, does that give the "impression" of capacity loss if you then take it out of this cool charging environment into a noticeably warmer daytime asphalt environment? Ex; You keep the same amount of water in the pool but the pool gets bigger (capacity) later in the day?

Someone made the comment that they did not want to charge a pack at higher temps and then put the car in a cool environment for risk of "overcharging". If this is true, then would the reciprocal happen going from cold to warm and creating "undercharging".

 

[edatoakrun]

As far as I can tell the most technically savvy on MNL are not even sure of the usable capacity in a LEAF.

Because it doesn't have a single value.

Yes. It is surely very difficult to shoot at a moving target. Which also leads me to a question.

If a LEAF charging overnight on a cooled pack is also finishing its charging during the coolest part of early morning, does that give the "impression" of capacity loss if you then take it out of this cool charging environment into a noticeably warmer daytime asphalt environment? Ex; You keep the same amount of water in the pool but the pool gets bigger (capacity) later in the day?

Someone made the comment that they did not want to charge a pack at higher temps and then put the car in a cool environment for risk of "overcharging". If this is true, then would the reciprocal happen going from cold to warm and creating "undercharging".

Actually, I was wondering about the timing of charges, by the sufferers of bar loss, for the the "overcharging" case.

If you plug in and charge to 100% as soon as you get home in the evening, when your battery is hottest, you are really "topping off" your capacity.

Even if you charge by timer, your battery is probably still pretty warm at 10-12:00 PM(?), when you begin to charge, and charging heats it up even more.

And if you then let the car sit overnight for the battery to cool down to the lowest ambient temperature the next morning...

 

[KJD]

And if you then let the car sit overnight for the battery to cool down to the lowest ambient temperature the next morning...

No need to let it sit all night long. Just set the charge schedule with an "End Time" and leave the start time empty. This will give your battery plenty of time to cool off.

The car figures out when to start and it will finish before you need it the next morning. My timer is set to finish at 7 AM and I leave for work at about 7:30. Works great.

 

[Herm]

Someone made the comment that they did not want to charge a pack at higher temps and then put the car in a cool environment for risk of "overcharging". If this is true, then would the reciprocal happen going from cold to warm and creating "undercharging".

I believe that is correct... but note that the Leaf only allows charging up to 4.10V under any condition, thats your safety margin if you later experience lower temperatures while at full charge..

 

[Cheezmo]

I have become really concerned in the past few days as my battery temp, which always used to be at 5 bars, is now occasionally at 6 bars after charging in the sun.

How do you think I feel with 6 bars after sitting in the garage not even plugged in over night! The horror.

 

[Herm]

Because it doesn't have a single value.

Manufacturers rate their batteries at a standard condition (room temperature), pouch cells should also be rated at a standard force pressing (besides atmospheric pressure) on their flat sides.. but good luck with Nissan telling us. Cylindrical cells are different, the metallic cans will maintain the laminations in close contact.