2019 Leaf battery overheating

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An interesting experiment would be to park it in ac garage and see how long it takes to cool off. I've already noticed a big lag time. Such that at 11am (lunch) the temps are just as low as 6am or even lower. The temp of the pack seems to lag outside temp curve by a few hours. It's a big thermal mass and it has a cover or maybe even insulation so I suppose that all makes sense.
 
danrjones said:
An interesting experiment would be to park it in ac garage and see how long it takes to cool off. I've already noticed a big lag time. Such that at 11am (lunch) the temps are just as low as 6am or even lower. The temp of the pack seems to lag outside temp curve by a few hours. It's a big thermal mass and it has a cover or maybe even insulation so I suppose that all makes sense.

Right, a high thermal resistance to ambient. Good for a short drive from a cool location to a hot location for a short time,
and then a short return trip (no fast driving or charging allowed).
 
danrjones said:
An interesting experiment would be to park it in ac garage and see how long it takes to cool off. I've already noticed a big lag time. Such that at 11am (lunch) the temps are just as low as 6am or even lower. The temp of the pack seems to lag outside temp curve by a few hours. It's a big thermal mass and it has a cover or maybe even insulation so I suppose that all makes sense.

Just watching it cool on a chilly night after a hot day will yield the same information. I air condition my garage during really hot weather. but haven't done those observations. I try to avoid a hot pack whenever possible.
 
After driving my 2019 40kWh for a little over 2K miles, the battery temperature appears to be fairly predictable at about 5-10F max above
ambient under the following conditions:

1. The vehicle speed is kept to a maximum of 50-55 MPH, i.e. level terrain & slower @ higher grades.
2. No daytime charging & one charge per day at L2 max.
3. Minimum use of A/C or heat.

The above typically yields about 5-5.5 miles/kWh efficiency.
 
smkettner said:
danrjones said:
At 6 am my battery temps were 92 and 89.4 max and min. That's with no charging. Plan to repeat tonight but with 2 hrs of lvl 2 from 3 to 5am.
Anyone know the optimum temperature?
Or the normal range for longest life?

Optimum temp for long life, DK. Best temp to fast charge is around 86-88º F.

Below that, you get early current ramp down (knee) above that, you get less than full current on charge start. So unless you have "Wallenda" blood in you, you are pretty much screwed...

Well, maybe not screwed but...
 
danrjones said:
An interesting experiment would be to park it in ac garage and see how long it takes to cool off. I've already noticed a big lag time. Such that at 11am (lunch) the temps are just as low as 6am or even lower. The temp of the pack seems to lag outside temp curve by a few hours. It's a big thermal mass and it has a cover or maybe even insulation so I suppose that all makes sense.

I have a lot of data on cooling of 30 kwh pack verses 40 kwh pack and its like night and day. A few times, parked 30 kwh pack with temps 125+ºF and less than 8 hours later pack would be in upper 70's.

The 40 kwh pack, I had at 109.2 º the other day and 10 hours later, it was 85º. I park my 30 at under about 105º and it would be within 2º of ambient in 10 hours.

The only good part of the 40 is that it does not heat up as quickly from ambient only temps. Today, I got to work, batts 73.4º. Highs hit 96º and batts were only 83º and that is sitting nearly 11 hours in direct Sun on asphalt.
 
DaveinOlyWA said:
cwerdna said:
metricus said:
The Leaf already has a TMS for the stator and the onboard charger. Beats me why they did not add the battery pack to the circuit. But that's another topic.
They probably have different ideal operating temps.

Way different and not very effective. The charger gets quite warm even with L2 charging (it does not heat up during DCFC sessions) so well above "pack prime" temps.
Indeed. Just L2 charge for at least an hour and the whole PDM stack gets pretty warm. And, it gets a bit warm near the inlet, as well.

You wouldn't want to dump that warm coolant into the battery pack except when the pack's too cold.
 
cwerdna said:
Just L2 charge for at least an hour and the whole PDM stack gets pretty warm. And, it gets a bit warm near the inlet, as well.

So you have been actually taking temperature measurements while L2 charging?

cwerdna said:
You wouldn't want to dump that warm coolant into the battery pack except when the pack's too cold.

Are you inferring that's a factor for Nissan's not using part of the cooling system to also cool the battery?
 
lorenfb said:
After driving my 2019 40kWh for a little over 2K miles, the battery temperature appears to be fairly predictable at about 5-10F max above
ambient under the following conditions:

1. The vehicle speed is kept to a maximum of 50-55 MPH, i.e. level terrain & slower @ higher grades.
2. No daytime charging & one charge per day at L2 max.
3. Minimum use of A/C or heat.

The above typically yields about 5-5.5 miles/kWh efficiency.

Well number 3 is out. I'm using the AC. It was 106 today. Nice idea though.
 
lorenfb said:
cwerdna said:
Just L2 charge for at least an hour and the whole PDM stack gets pretty warm. And, it gets a bit warm near the inlet, as well.

So you have been actually taking temperature measurements while L2 charging?
Sorry, no but it's easy to see for yourself. L2 charge for an hour or more even in a cool environment in the shade (e.g. concrete parking structure) or at night. While charging or shortly after it's stopped, open the hood and notice the whole PDM stack is warm (not quite hot) and warmer than body temperature and ambient temp.

You'll also notice warmth around the inlet area.
lorenfb said:
cwerdna said:
You wouldn't want to dump that warm coolant into the battery pack except when the pack's too cold.

Are you inferring that's a factor for Nissan's not using part of the cooling system to also cool the battery?
Yes. Circulating coolant heated by the on-board charger would almost certainly heat the battery pack in many/most cases.

Except during hot summer days, it's rare for my '13 battery pack to hit 90 F or higher, esp. given my car has no CHAdeMO. L2 charging from say 30-ish% to 80% on my '13 Leaf doesn't heat the battery much, only a few degrees F.
 
cwerdna said:
lorenfb said:
cwerdna said:
Just L2 charge for at least an hour and the whole PDM stack gets pretty warm. And, it gets a bit warm near the inlet, as well.

So you have been actually taking temperature measurements while L2 charging?
Sorry, no but it's easy to see for yourself. L2 charge for an hour or more even in a cool environment in the shade (e.g. concrete parking structure) or at night. While charging or shortly after it's stopped, open the hood and notice the whole PDM stack is warm (not quite hot) and warmer than body temperature and ambient temp.

You'll also notice warmth around the inlet area.
lorenfb said:
cwerdna said:
You wouldn't want to dump that warm coolant into the battery pack except when the pack's too cold.

Are you inferring that's a factor for Nissan's not using part of the cooling system to also cool the battery?
Yes. Circulating coolant heated by the on-board charger would almost certainly heat the battery pack in many/most cases.

Nissan could've easily installed bypass valves, i.e. route coolant around the battery during L2. That's a non-issue for Nissan's non-use of TMS.
 
danrjones said:
lorenfb said:
After driving my 2019 40kWh for a little over 2K miles, the battery temperature appears to be fairly predictable at about 5-10F max above
ambient under the following conditions:

1. The vehicle speed is kept to a maximum of 50-55 MPH, i.e. level terrain & slower @ higher grades.
2. No daytime charging & one charge per day at L2 max.
3. Minimum use of A/C or heat.

The above typically yields about 5-5.5 miles/kWh efficiency.

Well number 3 is out. I'm using the AC. It was 106 today. Nice idea though.

Actually, use of A/C will have minimum effect on raising the battery temperature compared to 1&2.
You have LeafSpy, just evaluate the battery temperature with & without A/C as you drive.
A/C consumes about 4/8 kW, that's about 10/20 battery amps. Battery power is (20^2 X .05 ohms) only 20 watts,
 
Data:

No charge overnight:

Sunset temps: 100.9 max 97.9 min
6am: 92.0 max 89.4 min

Charge from 3am to 5am Lvl 2 (42 to 76% SOH)

Sunset Temps: 101.8 max 100.0 min
6am: 94.4 max 89.6 min

So with this one data point it appears the 2 hour level 2 charge did not drastically change my temps compared to a non charging the night before.
The car was slightly warmer at sunset from a hotter day and so it was slightly warmer the next morning, but not by much.

Based on this data, Lvl 1 charging to keep it cooler would not be needed?
 
danrjones said:
Data:

No charge overnight:

Sunset temps: 100.9 max 97.9 min
6am: 92.0 max 89.4 min

Charge from 3am to 5am Lvl 2 (42 to 76% SOH)

Sunset Temps: 101.8 max 100.0 min
6am: 94.4 max 89.6 min

So with this one data point it appears the 2 hour level 2 charge did not drastically change my temps compared to a non charging the night before.
The car was slightly warmer at sunset from a hotter day and so it was slightly warmer the next morning, but not by much.

Based on this data, Lvl 1 charging to keep it cooler would not be needed?

Yes!
 
lorenfb said:
Nissan could've easily installed bypass valves, i.e. route coolant around the battery during L2. That's a non-issue for Nissan's non-use of TMS.
True, but it's debatable how helpful running coolant thru the pack that will be generally no cooler than outside air temps will be, when DC FCing.

Again, there are added complexities of how to cool the modules/cells w/coolant that's fed into the pack. Examples below:
https://media.gm.com/media/us/en/chevrolet/home.detail.html/content/Pages/news/us/en/2011/Feb/0214_battery.html
https://gm-volt.com/2013/08/02/spark-ev-versus-volt-battery/

Also, I stumbled across http://www.mychevroletvolt.com/chevy-volt-battery-cooling-systems-algorithms about operating temps of the various systems on separate loops on the Volt.
 
cwerdna said:
lorenfb said:
Nissan could've easily installed bypass valves, i.e. route coolant around the battery during L2. That's a non-issue for Nissan's non-use of TMS.
True, but it's debatable how helpful running coolant thru the pack that will be generally no cooler than outside air temps will be, when DC FCing.

Again, there are added complexities of how to cool the modules/cells w/coolant that's fed into the pack. Examples below:
https://media.gm.com/media/us/en/chevrolet/home.detail.html/content/Pages/news/us/en/2011/Feb/0214_battery.html
https://gm-volt.com/2013/08/02/spark-ev-versus-volt-battery/

Also, I stumbled across http://www.mychevroletvolt.com/chevy-volt-battery-cooling-systems-algorithms about operating temps of the various systems on separate loops on the Volt.

Oh OK, so no point to TMS, right? So Tesla and others that use TMS should have followed Nissan. Got it.

Actually, given the Leaf battery's high thermal resistance to ambient, the battery's temp can be reduced below ambient with active cooling.
Remember, a vehicle's interior temp can be reduced below ambient with A/C, e.g. compress freon and then allow it to expand.
 
lorenfb said:
After driving my 2019 40kWh for a little over 2K miles, the battery temperature appears to be fairly predictable at about 5-10F max above
ambient under the following conditions:

1. The vehicle speed is kept to a maximum of 50-55 MPH, i.e. level terrain & slower @ higher grades.
2. No daytime charging & one charge per day at L2 max.
3. Minimum use of A/C or heat.

The above typically yields about 5-5.5 miles/kWh efficiency.

I noticed something similar. At low highway speeds the battery does loose heat although very slow. I also DC charged and after jumping to 41C it returned eventually to 35C while OT was 24C and night time.

However if I drive at turnpike speeds 120 km/h - 70 mph and DC charge I go on red as per OP.

So the conditions for achieving a thermal balance are pretty drastic IMHO. Even so, DC charging at 35C results in a charge power of about 24 kW which sucks big time.
 
Liquid coolant from radiator cannot cool a battery below ambient temperature. Active cooling using a refrigeration process (air conditioning compressor, for example) is necessary if it is desired to cool a battery during summer. I had ambient temperature of 112 F on Wednesday evening in the shade--radiator coolant circulation through the battery would not help. On the other hand, the onboard charger gets hot enough to warm the radiator enough to cause the fans to turn on once in a while so liquid cooling with radiator is suitable for the power electronics.
 
Yesterday AM my SOH 97.42%

Tonight it is 96.49%

That's basically one full percent in 30 hours or so.

At this rate I'll get a free battery by the end of next week. Lol

I really wonder in hot climates if Nissan gave us too much warranty. I have ten years to hit 70%?
 
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