Windows down when charging?

[Mx5racer]

Do you leave the windows down when charging?
It seems like it would keep the interior/batteries cooler,
Or, is it not worth the effort to remember to roll them down?

 

[TomT]

The batteries are sealed in a case that is external to the passenger compartment so it makes no real difference either way.

Do you leave the windows down when charging?
It seems like it would keep the interior/batteries cooler,
Or, is it not worth the effort to remember to roll them down?

 

[ksnogas2112]

During charging doesn't matter but parked on an asphalt parking lot all day at work I find the battery temp is a little lower. How much lower I haven't been able to get the blue tooth battery app thing yet so I can't say for sure. Basically and hour or two won't really make a difference but all day in direct sun it will.

 

[GetOffYourGas]

During charging doesn't matter but parked on an asphalt parking lot all day at work I find the battery temp is a little lower. How much lower I haven't been able to get the blue tooth battery app thing yet so I can't say for sure. Basically and hour or two won't really make a difference but all day in direct sun it will.

By extension, it might make a difference when quick charging. I don't have any QCers nearby, but somebody with an OBDII reader should be able to test this one out. But I would expect even in this case, the difference in heat will be minimal.

 

[adric22]

The batteries are sealed in a case that is external to the passenger compartment so it makes no real difference either way.

I have wondered about this, but I'm not convinced that's true. Some heat is still bound to transfer between the passenger compartment and the battery. And I know with the windows rolled up on a hot summer day it can be 175 degrees and some cases more on the inside of the car. That heat likely radiates away from the passenger area in all directions, including down.

 

[LEAFfan]

During charging doesn't matter but parked on an asphalt parking lot all day at work I find the battery temp is a little lower. How much lower I haven't been able to get the blue tooth battery app thing yet so I can't say for sure. Basically and hour or two won't really make a difference but all day in direct sun it will.

By extension, it might make a difference when quick charging. I don't have any QCers nearby, but somebody with an OBDII reader should be able to test this one out. But I would expect even in this case, the difference in heat will be minimal.

It makes a big difference when QCing, especially when you start with 7 TBs. A few months ago, it was 100F ambient/7 TBs with a 30 min. QC. My highest TS after 30 mins and 90% was 112F. When it was 117F ambient yesterday, the highest TS was 104F/8 bars.

 

[GetOffYourGas]

During charging doesn't matter but parked on an asphalt parking lot all day at work I find the battery temp is a little lower. How much lower I haven't been able to get the blue tooth battery app thing yet so I can't say for sure. Basically and hour or two won't really make a difference but all day in direct sun it will.

By extension, it might make a difference when quick charging. I don't have any QCers nearby, but somebody with an OBDII reader should be able to test this one out. But I would expect even in this case, the difference in heat will be minimal.

It makes a big difference when QCing, especially when you start with 7 TBs. A few months ago, it was 100F ambient/7 TBs with a 30 min. QC. My highest TS after 30 mins and 90% was 112F. When it was 117F ambient yesterday, the highest TS was 104F/8 bars.

I'm not sure we're talking about the same "it". I was referring to the original question of whether leaving the windows down while charging would make a difference in temperature, in this case for QCing. You seem to be referring to the act of QCing itself.

From what I've read and experienced, it seems the battery is pretty well insulated, and the cabin air doesn't have all that much affect on the battery temperature. But you should be able to test this by comparing QC sessions with the windows up and down.

 

[kovalb]

The batteries are sealed in a case that is external to the passenger compartment so it makes no real difference either way.

Heat is conducted through the battery case to/from the surrounding air. The two primary paths are either the bottom, where it can pick up heat radiated from the ground surface, or from the top, where it can gain heat from the passenger compartment. Even if not a physical part of the passenger compartment heat will still travel.

Regarding DC fast charging, the heat generated is internal (due to pushing current through internal resistance) so putting windows down does not affect it. However if the cabin is hot putting the windows down can help, it would depend upon the difference in temperature it makes and for how long it is done.

 

[EVDRIVER]

Having the windows down during a 15 min QC in not going to impact the pack temp.

 

[GetOffYourGas]

Regarding DC fast charging, the heat generated is internal (due to pushing current through internal resistance) so putting windows down does not affect it.

This is perhaps a little too simplified for what I was thinking. With regards to heat, there will be sources (e.g. QC) and sinks (e.g. ambient air cooler than the battery). The idea was that if either the cabin air were cooler, it would either sink more heat or at least source less of it. In combination with the QCing, the effect may be noticeable.

However if the cabin is hot putting the windows down can help, it would depend upon the difference in temperature it makes and for how long it is done.

This was the second half of my thought. Again, in combination with QC, would this not be more noticeable?

I'm also working on the idea that the difference between 70-90F is not nearly as bad for the battery as the difference between 90-110F.

 

[gbarry42]

As stated above, heat flows from hot to cold. So, you have to find that the battery is warm and the temperature in the cabin lower. Early on, after a 240V charge, I went and felt the floor. I also pulled up the carpet over the disconnect and felt the metal there. I couldn't tell--maybe it was barely warm, or maybe I was just imagining it. So, hardly at all to not at all. I also asked Tony Williams to measure the temperature of the battery case after some fast charging (during last year's BC to BC run) and he said there was no discernible temperature rise.

So, the battery may heat up, but it takes a long time for that heat to escape. It comes out slowly.

Attempting to measure a difference with windows up or down...I think any difference would disappear into the noise--it's hard to repeat the exact same conditions each time.

I do leave the window down in the garage. But that's so I can open the charge door when I forget, or hit the timer-off button if I need to