Extreme Heat, Battery Degradation, and Cabin Overheat Protection

[Regaj]

It's well known that high temperatures are a serious threat to the health and longevity of lithium-ion batteries. And so as a new Model 3 owner wishing to minimize battery degradation resulting from extended high heat exposure... my question is does anyone have any data on the effectiveness of Cabin Overheat Protection in protecting the battery? Nearly all the discussions of COP I've seen speak to how well the feature cools the cabin, or how much SOC one loses in a day when it is turned on. Virtually nothing on how effective, or not, it is in support of the battery.

I live in a rural area and I'm one of those people who do not have a garage. The M3's parking spot is in the sun most of the day. I do have the option of moving it to a largely shaded spot, but there is no access to its L2 charger when I put it there.

I have the wiring harness for Scan My Tesla on order, so will shortly be able to obtain pack temperatures. But in the meantime, if anyone has already been down this road, I'd love some guidance.

TIA...

 

[Empiro]

Cabin overheat protection only protects the cabin. The battery is underneath your car and isn't that affected by cabin temperature. The car will automatically cool the battery if necessary. Just make sure to keep the car at a reasonable state of charge (40%-60%). Keeping it plugged in is good.

 

[Regaj]

Cabin overheat protection only protects the cabin. The battery is underneath your car and isn't that affected by cabin temperature. The car will automatically cool the battery if necessary. Just make sure to keep the car at a reasonable state of charge (40%-60%). Keeping it plugged in is good.

From the Model 3 Owner's Manual, under the Cabin Overheat Protection section...

"In addition to cooling the interior, the air conditioning compressor also cools the Battery. Therefore, in hot weather, the air conditioning compressor can turn on even if you turned it off. This is normal because the system’s priority is to cool the Battery to ensure it stays within an optimum temperature range to support longevity and optimum performance."

I agree that battery pack temperature is likely different from the temps the cabin is experiencing. But how different? With the battery pack being attached to the floor of the cabin, I could imagine that excessive heat in the cabin could result in some of that heat transferring into the pack.

It sounds like even if one turned COP off, the battery management system would engage AC cooling at some point to bring the battery pack back in line. I'd love to know what threshold that happens at.

Like you say... keeping the vehicle plugged in and at a reasonable state of charge is certainly good practice in hot weather!

Thanks for the reply.

 

[mr.wattson]

I wonder if the AC unit does have a way to cool down the battery too by circulating down some "channels" in the battery pack.

Similar to what Peter Rawlinson described in the second half of this talk:

 

[tadamonoron]

I wonder if the AC unit does have a way to cool down the battery too by circulating down some "channels" in the battery pack.

Similar to what Peter Rawlinson described in the second half of this talk:

That was a nice talk, indeed!

 

[Candleflame]

The temperature while stationary will never really be hot enough for the car to actively cool the battery. the battery has to be above... 45C i think for the car to actively cool the battery.

 

[sorbl]

The temperature while stationary will never really be hot enough for the car to actively cool the battery. the battery has to be above... 45C i think for the car to actively cool the battery.

Dunno about the battery pack, but the cabin temperature would easily exceed that in Texas in the summer.

OTOH, I have a hard time imagining a circumstance in which the battery pack temperature greatly exceeds the cabin temperature. So, if you have cabin overheat protection turned on, I think it's safe to assume the battery temperature will stay below 45℃.

 

[Brando]

Seems it might be best to read the manual from YOUR vehicle and see what it says. This is from a google search:
(i.e. not all batteries = AND chemistries are constantly changing over the years)

The normal range for prolonged battery life is 62 to 72 degrees Fahrenheit. High temperatures over 95 degrees (35 degrees Celcius) can decrease battery life and temperatures lower than 50 degrees (10 degrees Celcius) can permanently shorten battery life.Oct 7, 2015

 

[Candleflame]

Dunno about the battery pack, but the cabin temperature would easily exceed that in Texas in the summer.

OTOH, I have a hard time imagining a circumstance in which the battery pack temperature greatly exceeds the cabin temperature. So, if you have cabin overheat protection turned on, I think it's safe to assume the battery temperature will stay below 45℃.

cabin temperature also easily exceeds this in summer in germany. thats just due to the greenhouse effect. the battery is is big and solid and underneath the car.

In fact, given that i lived in the tropics i can tell you that the battery is a little bit cooler than ambient air normally. like if its 35C outside the battery sits at around 31-32C.