Turn on Remote AC/charging heats up battery from air flow

[yujungchang]

Not sure if anyone notice this, using remote AC while charging can heat up the battery more than 10 degrees greater than ambient temperature. I installed a remote thermometer on my car battery and kind of noticed that earlier, but just didn't look into further. My thermal sensor is attached to the battery case, on the middle surface towards the end on the battery case. I always thought maybe that was because of charging, so the battery case temperature goes up while charging. Given it reaches more than 100 degree in Sacramento, the battery ambient temperature can actually be 10 degree higher than outside.

When I open up the handle cover(for high voltage contactor) on the back seat floor this week (while it's charging and AC was on), I noticed that there were some warm air blowing from front engine area (inverter?) to the battery. The warm air disappeared right after I turn off the car/AC and then I felt the cool air from cabin rush through my hand to the battery. When I turn the car back on with AC, the temperature reported from the sensor went up after just few minutes and I felt that warm air again. Open the engine cover, I can feel the inverter(the one near the fire wall) or most components in the engine bay are quite hot.

This is less of a concern when the car is moving, because the air will flow through the battery and reduce the temperature. However when the car is parked/charging, I think it poses some concern(especially in a hot area). Has anyone notice this?

 

[aarond12]

I noticed this yesterday in my EV. (Not a LEAF, but I'm here because my next EV will likely be a LEAF.) I pre-cooled my i-MiEV and noticed the temperature gauge showed 109°F as the outside temperature. I knew the temperature was 95°F. As I drove, the gauge slowly dropped to 95°F so I figured it was affected by the ambient air from the A/C compressor.

 

[BIGneutrino]

This is interesting data. I will be placing a remote thermometer in the HV access area to start making some observations too. If there could be a way to manipulate the air flow to/from the battery tray area via the HV access area in the rear passenger footwell, it could potentially be beneficial for my longer trips with repetitive use of DC quick charging.

Thank you for sharing!

 

[DaveEV]

Yes, this has been noticed before.

Make sure you insulate your thermal sensor with some foam tape so that you are actually measuring case temperature rather than air temperature, I suspect the amount of actual temperature rise will be less.

Have to cross-checked your temperature data with LeafSpy or LeafDD? I highly doubt that the battery temperature will change more than a degree or so.