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Re: 2019 Leaf battery overheating

Posted: Wed Jun 12, 2019 11:18 am
by danrjones
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.

Re: 2019 Leaf battery overheating

Posted: Wed Jun 12, 2019 12:28 pm
by lorenfb
danrjones wrote: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).

Re: 2019 Leaf battery overheating

Posted: Wed Jun 12, 2019 1:39 pm
by smkettner
Not sure I would want to add air conditioning to the garage. Although a heat pump style water heater should cool the garage some.

Re: 2019 Leaf battery overheating

Posted: Wed Jun 12, 2019 2:22 pm
by LeftieBiker
danrjones wrote: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.

Re: 2019 Leaf battery overheating

Posted: Wed Jun 12, 2019 7:07 pm
by lorenfb
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.

Re: 2019 Leaf battery overheating

Posted: Wed Jun 12, 2019 7:17 pm
by DaveinOlyWA
smkettner wrote:
danrjones wrote: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...

Re: 2019 Leaf battery overheating

Posted: Wed Jun 12, 2019 7:26 pm
by DaveinOlyWA
danrjones wrote: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.

Re: 2019 Leaf battery overheating

Posted: Wed Jun 12, 2019 7:39 pm
by cwerdna
DaveinOlyWA wrote:
cwerdna wrote:
metricus wrote: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.

Re: 2019 Leaf battery overheating

Posted: Wed Jun 12, 2019 9:35 pm
by lorenfb
cwerdna wrote: 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 wrote: 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?

Re: 2019 Leaf battery overheating

Posted: Wed Jun 12, 2019 10:13 pm
by danrjones
lorenfb wrote: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.