Battery temp close to max in hot weather - How bad?

[tedot]

Call me a nervous nanny, but I plan on keeping my 62kwh leaf for the long term. It lives outside but on hot days I pull the car in when my wife is at work.

We're having an extremely warm weather spell here in Southern california this week and I didnt think much of it and took the leaf on a 100 mile round trip. By the time I got home, the battery temp was close to the redline, but not quite there.

The battery had gotten down to about 17% by the time I got home, I didnt dare charge it at that temp. I let it sit for about a day before charging it again.

How bad is it to drive the leaf with the battery temp near the max? Here's a pic for reference on how hot it got... It took an entire day for it to come down a little from where it was at.

[LeftieBiker]

By the time I got home, the battery temp was close to the redline, but not quite there.

The battery had gotten down to about 17% by the time I got home, I didnt dare charge it at that temp. I let it sit for about a day before charging it again.

If that happens again, charge the car with L-1 or L-2 to something over 20+, then let it cool before further charging.

Running a pre'18 Leaf hot would have made us all wince. Doing it with a post 2018 pack makes us as much curious as filled with dread - just not enough info yet, other than Gerry running an ePlus in Arizona with no apparent ill effects.

[Stanton]

By the time I got home, the battery temp was close to the redline, but not quite there.

The battery had gotten down to about 17% by the time I got home, I didnt dare charge it at that temp. I let it sit for about a day before charging it again.

If that happens again, charge the car with L-1 or L-2 to something over 20+, then let it cool before further charging.

What? No! The OP absolutely did the right thing when he was that close to redline.
Charging a battery that hot (unless literally empty) is about the worst thing you can do. Even now, I try to avoid charging my battery pack above 6 TB; with my new pack I even monitor charging temps (via OVMS) and unplugging if I hit 7 TB. We know heat degrades Lithium cells (even in a phone, etc.) in the long run. The worst case scenario: many miles at high speeds in high temps.

[WetEV]

How bad is it to drive the leaf with the battery temp near the max? Here's a pic for reference on how hot it got... It took an entire day for it to come down a little from where it was at.

In an absolute way, is hard to say. There isn't enough public information.

In a general way, increasing temperature by 10C roughly halves life. So if you increased from 20C to 40C you would use roughly four days of normal battery life per day at higher temperatures.

This makes a pile of assumptions. The biggest is that calendar aging is the largest source of loss, which was clearly true with earlier LEAFs, but might no longer be true.

[LeftieBiker]

As you can see, there is no unified opinion on this. Here is my rationale for charging just to 20% or so even with a hot battery: L-1 and L-2 charging do not seem to raise battery temperature enough to produce a measurable increase in it, unless it goes on for hours. OTOH, it is generally considered to be true that sitting for hours with a state of charge below 20% isn't good for battery health. So I'm basically choosing to mitigate the known harm with what I think is a lesser harm. I could be wrong, Stanton could be wrong, or we could both be right, to some degree...

[DougWantsALeaf]

For what it's worth, I have run both of my Plus Leafs (both 2019) to red with 4 and 5 back to back DC charges and after 3+ years are at 91 and 93% SoH, do as long as you don't do it too much, it hasn't been too damaging.

[GerryAZ]

The temperature of the battery in my 2019 SL+ reached 11 bars (middle of red zone) after a DCQC and 65 miles of mostly freeway driving. It cooled to 10 bars (bottom of red zone) after being parked for a couple hours. I needed to drive it the next day so I had no choice but to plug in and let it charge at L2 overnight. It did continue to cool overnight even while charging at full 6.6 kW rate. The 62 kWh battery has more thermal mass than the 24 kWh battery in the 2015 (or 2011) so it takes longer to cool down to ambient than the earlier cars.

Since you apparently did not need the range (or to use the car the next day), I think you made the right choice to allow the battery to cool a bit before charging. SOC of 17% is not really low so I am not concerned that you did not charge it right away. If you do run it down to VLBW (very low battery warning with SOC of less than 2%), then it would be prudent to charge enough to get above LBW (low battery warning which is about 6% SOC) before letting it sit for extended time. My experience has been that the 62 kWh battery in my 2019 is doing much better in the Phoenix climate than the 24 kWh battery in the 2015--you can read my posts in the 62 kWh thread for more information.

[johnlocke]

Keep in mind that 17% indicated on the dash has a lot of hidden reserve. Check it with Leafspy. 20% indicated on my SL+ is actually about 240 GID's. YMMV. I'd check it next time. It might not be as bad as you think.

[DaveinOlyWA]

Call me a nervous nanny, but I plan on keeping my 62kwh leaf for the long term. It lives outside but on hot days I pull the car in when my wife is at work.

We're having an extremely warm weather spell here in Southern california this week and I didnt think much of it and took the leaf on a 100 mile round trip. By the time I got home, the battery temp was close to the redline, but not quite there.

The battery had gotten down to about 17% by the time I got home, I didnt dare charge it at that temp. I let it sit for about a day before charging it again.

How bad is it to drive the leaf with the battery temp near the max? Here's a pic for reference on how hot it got... It took an entire day for it to come down a little from where it was at.

Not a whole lot to worry about. Your pack isn't really all that hot.

SOC management is probably more important. Keep it below 80% if possible. As far as letting it sit at 17% for a day? The dash is hiding a hidden buffer so you are closer to 25% so ok but its not a good idea to keep it a low SOC either. Less critical than a high SOC but still not ideal.

[Marktm]

Has anyone correlated the (2021) temperature bar with actual LS temp readings? I know that the mid point of the bar are temps in the high 80's to mid 90's oF. Have not gotten any hotter.