Public Charging/Hot Battery

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iamchemist

Well-known member
Joined
Mar 18, 2011
Messages
57
Location
Wilmington, NC
Have LEAF owners considered the inconsistency between the LEAF Manual's recommendation not to charge the battery, when it's hot, and the use of public charging equipment? If I find that my LEAF needs a little extra charging during the afternoon, I allow the car to sit and the battery to cool for 1 to 1 1/2 hours, before I connect it to my Level 2 charger. Some owners on this forum have recommended several hours of battery cool down time, before such charging, which would pretty much entirely rule out adding adding any charge to the car during the afternoon.

However, it seems to me that the logistics of using a public charger will typically dictate that the car be pulled into the charging spot (typically with a hot battery from driving) and immediately connected to the public charger for some period of time. There will typically be no time to allow for any significant battery cool down before charging. Yet, Nissan states in the LEAF Manual that charging a hot battery will shorten battery life. It would seem that the use of a DC Fast Charger with an already hot battery would create an even greater problem. What do owners think about this? Do EV's with active battery temperature control systems have a much reduced problem in this regard?

I live in North Carolina, and there are no DC Fast Chargers anywhere near me currently, but it appears that this issue would get much worse in the future as both Level 2 and DC Fast Chargers become more common. :?:
 
iamchemist said:
Nissan states in the LEAF Manual that charging a hot battery will shorten battery life. It would seem that the use of a DC Fast Charger with an already hot battery would create an even greater problem. What do owners think about this? Do EV's with active battery temperature control systems have a much reduced problem in this regard?
Click to expand...

It's not charging when hot that is the problem... It's the heat generated in addition to whatever other ambient heat the battery is exposed to.

Of course TMS equipped cars handle this better. Virtually EVERY OTHER EV on the market has TMS.

There's a reason to have TMS; a whole lot of reasons. The only reason not to have it is that Nissan saves money by not including TMS and also not covering the battery under warranty for damage caused by heat (accelerated degradation).

We call this "Nissan-Normal(TM)".
 
Normal driving doesn't seem to raise the battery temp all that much. Neither does 240v/120v charging. DCQC does, and some folks who have done multiple sessions in one day have reported high temps. I'd be more concerned with hot weather than whether I was just driving or not before charging.
 
as long as Nissan continues to take the low road and fails to stand behind their battery with a decent warranty, we will all have to take our chances when it comes to fast charging and/or owning in hot climates.
 
iamchemist said:
Have LEAF owners considered the inconsistency between the LEAF Manual's recommendation not to charge the battery, when it's hot, and the use of public charging equipment?
Click to expand...
What is inconsistant about not charging? How hot is hot?
 
+1!

TonyWilliams said:
There's a reason to have TMS; a whole lot of reasons. The only reason not to have it is that Nissan saves money by not including TMS and also not covering the battery under warranty for damage caused by heat (accelerated degradation).

We call this "Nissan-Normal(TM)".
Click to expand...
 
OP: not sure I understand your question/statement. The Leaf's battery does not warm up appreciably just from driving. High battery temperature comes from DC quick charging or from very high ambient temperature. There is no issue with Level 2 or DC charging after a long drive in typical weather, unless your battery is still hot from a recent DCQC.
 
iamchemist said:
Have LEAF owners considered the inconsistency between the LEAF Manual's recommendation not to charge the battery, when it's hot, and the use of public charging equipment?
Click to expand...
I guess I missed this recommendation. Are you referring to the Owners Manual? Could you point me to a section or page? As others have suggested, we need to understand what "when it's hot" means, and I thought I might have a better chance of doing that if I could find the actual statement.

One thought - could it be something that was added to the 2012 manual, so I wouldn't be able to find it in my 2011 manual?

Ray
 
Last Saturday, I drove to Sacremento from Berkeley, did a 10 minute QC on the way, then a 10 minute QC once I arrived, switched to L2 (@ 6.7kW) to allow someone else to QC. I was full before I left the meeting. Went to lunch about 20 miles away, topped off on L2 while eating, came out to a Full Leaf, and then did 5 min QC on the way back. My batt temp started at 57 degrees, and at no time did it exceed 100. (I think the highest I saw was 97, and it was back below 90 in less than an hour)

Now if I tried that in Phoenix in the summer, things would be different, but here in the Bay area you can perform multiple QC's, and definitely plenty of L2's (even at 6.7kW) without worry.

I posted this explanation of how degradation works in another thread:
Ingineer said:
[extreme SoC] x [time] x [temperature] = degradation amount. (SoC factors are highest at either of the ends; discharged/fully charged)

So if you keep it at very high SoC (or very low) for a very short time it has very little effect, especially if it's cold. If you charge to full, then let it sit for a few days, and it's hot out, that's the worst-case.
Click to expand...

If you charge and the temperature rises a bit, as long as it doesn't sit there for long at elevated temps, it's not going to add much degradation.

-Phil
 
I sort of get the OP's question, so I'll try and answer it instead of jumping on the battery "dog pile" (which has been beat to death enough).

While I don't use public charging a lot, my general rule of thumb is: I don't (opportunity) charge the battery when I see 7TB's in the dash (which only happens in the peak of summer). I'll wait until I'm home at night to charge in the early AM (it takes a while to heat OR cool the battery pack). Does that mean sometimes I don't "push" the car for that extra trip in the summer? Yes. Has that really been a problem? No, because the Leaf isn't my only car. That doesn't mean I don't drive the Leaf 99% of the time, but there is that one or two weekends in August where I might take the ICE car out for a (long) trip instead of the Leaf to give the battery pack a rest. BTW, I didn't get QC port because I never intended the Leaf to be a long-distance car, and I also suspected that QC was a sure-fire way to reduce battery life.

There are similar special conditions for charging the Leaf in really cold weather (which we don't get in TX), like charging while the battery IS warm instead of waiting for the middle of the night. Bottom line: there may be concessions made to drive a BEV, but in the end I think they're worth it (especially one as fun as the Leaf).
 
Sure would be nice if SOMEONE would build a real battery temp gauge and offer it to the masses. :p

Ingineer said:
Last Saturday, I drove to Sacremento from Berkeley, did a 10 minute QC on the way, then a 10 minute QC once I arrived, switched to L2 (@ 6.7kW) to allow someone else to QC. I was full before I left the meeting. Went to lunch about 20 miles away, topped off on L2 while eating, came out to a Full Leaf, and then did 5 min QC on the way back. My batt temp started at 57 degrees, and at no time did it exceed 100. (I think the highest I saw was 97, and it was back below 90 in less than an hour)

Now if I tried that in Phoenix in the summer, things would be different, but here in the Bay area you can perform multiple QC's, and definitely plenty of L2's (even at 6.7kW) without worry.

I posted this explanation of how degradation works in another thread:
Ingineer said:
[extreme SoC] x [time] x [temperature] = degradation amount. (SoC factors are highest at either of the ends; discharged/fully charged)

So if you keep it at very high SoC (or very low) for a very short time it has very little effect, especially if it's cold. If you charge to full, then let it sit for a few days, and it's hot out, that's the worst-case.
Click to expand...

If you charge and the temperature rises a bit, as long as it doesn't sit there for long at elevated temps, it's not going to add much degradation.

-Phil
Click to expand...
 
smkettner said:
What is wrong with the Nissan battery temp guage?
What would you really do differently with one degree accuracy?
Click to expand...
I would use the temp gauge to determine how much I would use the car during hot months. Over the summer I did notice that charging during the heat of the day had a bad effect on GID count the next day. After I noticed this I rode the mountain bike on hot days more often. :cool:

If I had a real temp gauge I could record the battery temp vs GID count and find out what the correlation is. As it stands today it is only guess work.
 
TonyWilliams said:
smkettner said:
What is wrong with the Nissan battery temp guage?
What would you really do differently with one degree accuracy?
Click to expand...


Versus 50-ish degree accuracy? You can't see a distinction?
Click to expand...
5 bars or less charge at will including multiple QC to 100%
6 bars charge at L2 without worry but limit QC to 80%
7 bars limit L2 to 80%, QC only the minimum to reach destination.
8+ bars only charge as absolutely needed.

How close do the hairs need to be split?
Are you really going to park the car and walk at what point?
12 bars @ 50 degrees covers 600 degrees. Granularity is better where it matters. Bottom or top of normal you just drive.

Didn't you have all bars lit at some point in the BC-BC trip? but you kept rolling.

If you want to do GID counts vs temperature research.... OK but still when do you take the Prius?
 
Ingineer said:
Real progress is being made on getting it manufactured! =)
Click to expand...
Great to hear!
1
 

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