Does Model 3 ever heat the battery when parked? Conflicting info.

[thefrog1394]

Lots of ppl seem to think that the car will maintain a minimum battery temp to keep the battery from freezing when SOC is above 20%. E.g. this thread on X. Definitions of "freeze" differ, but the manual does note that you shouldn't leave the ambient temps below -30C.

Concern seems to be electrolyte freezing around -40C causing permanent damage. Presumably the coolant would freeze at some point as well.

In my part of the world, we don't really see temps below around 0F (-20C). I have yet to observe the car actively heating the battery outside of when charging or when the car is "started" (driver in the seat, brake pressed). The car seems to sleep without issue in cold temps.

So is there a lower limit at which the car will wake itself from sleep to run a battery heating cycle and prevent damage? Or is this an urban legend?

 

[Sti-g]

Don’t know. Though even if it did, it would be a loosing game. I don’t think the battery would last long trying to keep the battery pack ”warm”. And if you’re away from a charger, now you have even less energy to drive to a location where there’s a charger available.

 

[stopcrazypp]

Lots of ppl seem to think that the car will maintain a minimum battery temp to keep the battery from freezing when SOC is above 20%. E.g. this thread on X. Definitions of "freeze" differ, but the manual does note that you shouldn't leave the ambient temps below -30C.

Concern seems to be electrolyte freezing around -40C causing permanent damage. Presumably the coolant would freeze at some point as well.

In my part of the world, we don't really see temps below around 0F (-20C). I have yet to observe the car actively heating the battery outside of when charging or when the car is "started" (driver in the seat, brake pressed). The car seems to sleep without issue in cold temps.

So is there a lower limit at which the car will wake itself from sleep to run a battery heating cycle and prevent damage? Or is this an urban legend?

There's literally zero evidence it does this. There are modes that keep the car awake (Sentry, Cabin overheat, Summon standby), so it will keep the car in minimum discharge operating temperature in those cases. But when car is asleep there is no evidence there is heating going on. The car also occasionally wakes to top up the 12V battery, and there may be some heating of the HV battery to bring it back up to minimum operating in those cases.

As you point out, there is a warning about ambient temps below -30C for more than 24 hours. However, if the car is actively warming the car, it would never reach those temperatures (especially in a short time like 24 hours), so that seems to be proof the car isn't doing any active warming when asleep, especially at much higher temperatures.
https://www.tesla.com/ownersmanual/model3/en_us/GUID-7FE78D73-0A17-47C4-B21B-54F641FFAEF4.html

As another pointed out, warming the battery above freezing during sleep is pointless and a waste of precious energy. The generic bare battery cells can operate just fine above -20C (the typical minimum discharge spec for 18650s and 2170s; Tesla may have custom formulations that do even better) so there is no point in trying to maintain a temp well above that. It likely can operate even below those quoted specs (just at less discharge rate). There is also considerable thermal mass so it may take some time for it to drop.

 

[thefrog1394]

Interestingly my Model 3 just woke itself from sleep after it’s usual 17 or so hour sleep cycle, but has been awake for over 6 hours now.

The car did something similar earlier this week, but fell back asleep after a quick drive cycle.

Based on range loss over the past 6 hours, it seems to only be using under 200 watts, so definitely no heaters running. But odd that it’s not sleeping. Maybe 12V related?

Temps are up into the 30s here tomorrow so this is the last data pt I’ll have for a while.

 

[stopcrazypp]

Interestingly my Model 3 just woke itself from sleep after it’s usual 17 or so hour sleep cycle, but has been awake for over 6 hours now.

The car did something similar earlier this week, but fell back asleep after a quick drive cycle.

Based on range loss over the past 6 hours, it seems to only be using under 200 watts, so definitely no heaters running. But odd that it’s not sleeping. Maybe 12V related?

Temps are up into the 30s here tomorrow so this is the last data pt I’ll have for a while.

200W is pretty much the regular awake discharge. Do you have a pending update perhaps? The last weekend, I was staged for the 2023.44.30.8 and it was downloading and I was wondering if the car will keep downloading or sleep. It didn't finish downloading and seems to have been pulled (it never offered to retry).

From a quick search, it seems the car does not sleep if it's downloading an update. It seems there are a bunch of people stuck on a download loop of 2023.44.30.8 where it never finishes downloading and it keeps the car awake. That might be why they pulled it for me.

https://www.reddit.com/r/TeslaLounge/comments/194d14q

 

[thefrog1394]

Well just as soon as I posted that it went back to sleep haha. About 6 hours of wake time. I’m wondering if the 12V charging logic pushes a lot lower power into that battery when it’s cold to avoid damage.

Already on 44.30.8 and not connected to wifi so don’t think updates are a factor here.