Cold battery will not charge (-20C / -4F)

[jimbobb23]

You can precondition through the short cuts app on an iPhone without need to drive anywhere.

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[Jager]

Here in the mid-Atlantic we've been experiencing unseasonably cold temps the last few days. Highs in the 20's (F) during the day; and single digits at night. Not quite as cold as the OP, but within spitting distance.

When I came home from driving my CT yesterday afternoon the pack was ~65F. I plugged in and replaced the ~20 kWh I had just expended, while the pack was still warm. During the nearly three hours that charge took (like the OP, my TWC is on a 40-amp circuit), the pack retained most of its heat (it lost maybe 8-10 degrees).

Fifteen hours later, after sitting outdoors overnight (no garage), the now cold-soaked pack modules ranged from 17-22F.

I remotely turned Climate on and in about an hour the pack temp had risen to ~55F. I don't pretend to understand Tesla's BMS algorithm - some variability is evident - but typically I'll see about 7 amps, with occasional brief excursions to ~10 amps, when using Climate in that fashion to warm the pack.

What's clear is that, even when a full complement of kW are being delivered, there are obvious limitations to how fast a modern Tesla can heat its pack once that pack has become truly cold-soaked. Tesla has engineered an ingenious solution. But fast it's not.

My recommendation to anyone managing an EV in cold temps is to charge immediately upon returning from a drive. Whatever savings might otherwise be on the table with middle-of-the-night charging are almost certainly lost when conditions are such that pack temps fall precipitously.

 

[mongo]

What's clear is that, even when a full complement of kW are being delivered, there are obvious limitations to how fast a modern Tesla can heat its pack once that pack has become truly cold-soaked. Tesla has engineered an ingenious solution. But fast it's not.

Yeah, heating while plugged in is anemic. It can be fast, but they reserve that power level (16kW+) for on the road Supercharger preconditioning.

 

[MyOtherTruck]

You can precondition through the short cuts app on an iPhone without need to drive anywhere.

THIS! is the most useful post I have seen on this forum in a while because I didnt even mes with Shortcuts on my iphone before I read this. Now I have a bunch of Tesla Shortcuts on my homescreen - one of which isnt even in the tesla app! "precondition now". God bless this dude Jim Bob!

 

[AlmostHuman]

THIS! is the most useful post I have seen on this forum in a while because I didnt even mes with Shortcuts on my iphone before I read this. Now I have a bunch of Tesla Shortcuts on my homescreen - one of which isnt even in the tesla app! "precondition now". God bless this dude Jim Bob!

My understanding is the “Start Preconditioning Tesla” shortcut is the same as turning on the client in the app. At least that is all it does for me.

 

[mongo]

My understanding is the “Start Preconditioning Tesla” shortcut is the same as turning on the client in the app. At least that is all it does for me.

I sure hope so
-android user

 

[MyOtherTruck]

My understanding is the “Start Preconditioning Tesla” shortcut is the same as turning on the client in the app. At least that is all it does for me.

So it turns on the "climate"? Damn I was thinking it'd force the battery to get ready for a charge!

 

[AlmostHuman]

So it turns on the "climate"? Damn I was thinking it'd force the battery to get ready for a charge!

If the battery is cold enough turning the client on will warm the battery.

 

[Outdoors]

My recommendation to anyone managing an EV in cold temps is to charge immediately upon returning from a drive. Whatever savings might otherwise be on the table with middle-of-the-night charging are almost certainly lost when conditions are such that pack temps fall precipitously.

Agreed. When one deals with negative degrees in garage on a regular basis and one is done driving one charges immediately. It is a psychics thing. Pack get cold, pack needs to warm up to charge. Doing post driving increases the likelihood of a warmer pack.

The software bug will be fixed. Yet, I wouldn't rely on it for perfection. My drive in morning with slight morning conditioning and charging works great even with a -F garage.

 

[CyberGus]

What's clear is that, even when a full complement of kW are being delivered, there are obvious limitations to how fast a modern Tesla can heat its pack once that pack has become truly cold-soaked. Tesla has engineered an ingenious solution. But fast it's not.

Heating a cold-soaked pack is like defrosting a 1000-lb steak. It's gonna take a minute.

 

[trentsize]

Definitely a bug acknowledged by Tesla and confirmed that a fix is on the way. Those explaining that this is "normal behavior" don't know what they are talking about.
Good news is that a fix is coming.

Employees have already started receiving 2025.2 that is said to have the bug fix. Hopefully it’s on the FSD branch.

 

[jbuijk]

Employees have already started receiving 2025.2 that is said to have the bug fix. Hopefully it’s on the FSD branch.

Excellent. Thank you for the update. In the meantime (as long as we have the cold weather) I will charge the moment I come home rather than let the battery cool down.

 

[M0unt41nm4n]

I left my CT out for the night to let my son charge his F150 Lightening in my heated garage. It got to -10f. In the morning after he left, I fired up the CT and it was no problem. Interestingly when it's really cold outside, the heat pumps go nuts on the CT and are quite loud... loud enough outside the vehicle that you have to raise your voice to be heard. Either way, when I brought it in, it immediately started charging at full speed. I am guessing my heat pumps work rather well.

Second point... to the person who commented about Siri Shortcuts to precondition... this is awesome. The best tip I have seen in a. long time that is crazy useful. I will remember this one when I go to a non-Tesla DCS charger.

 

[M0unt41nm4n]

My understanding is the “Start Preconditioning Tesla” shortcut is the same as turning on the client in the app. At least that is all it does for me.

If you have only 1 Tesla, you can rename it to "Start Preconditioning" so you don't have to say Tesla in the command.

 

[AlmostHuman]

If you have only 1 Tesla, you can rename it to "Start Preconditioning" so you don't have to say Tesla in the command.

Nice. We have two but I don’t use the shortcuts yet. Maybe some day, change is scary ?

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