Preconditioning energy usage - plugged in vs. unplugged

[Rocky_H]

The Tesla vehicle's battery management system will only charge the battery if the pack temperature is at or above 50F (10C). If the battery pack is colder than 50F the Tesla vehicle will first warm the battery pack before charging.

That is very definitely not true and easily disproven. Are you thinking of something else?

What you are probably thinking of is that a little bit of regeneration limiting starts to show up about 50 degrees F or colder. But that just means that it can't take its full 60 or so kW of charging power. It can still CERTAINLY take 10 kW of charging at home in someone's garage. That is a very low power level that it can still easily take while it's a little colder than 50 degrees.

 

[jcanoe]

That is very definitely not true and easily disproven. Are you thinking of something else?

What you are probably thinking of is that a little bit of regeneration limiting starts to show up about 50 degrees F or colder. But that just means that it can't take its full 60 or so kW of charging power. It can still CERTAINLY take 10 kW of charging at home in someone's garage. That is a very low power level that it can still easily take while it's a little colder than 50 degrees.

Found this thread: Manually warm up battery?

Post #24 - I also have Scan My Tesla and actually did a similar thing this am. I think the difference may be I have a 2018 SR (single motor). All I did was tell the car to start charging, never opening the car. The pack started at 28F. SMT was showing it charging the pack with 3.5kW and the rear (only) stator running consuming 3.5kW as well. After about 1 hours the pack was up to 49F and that is when the rear stator stopped running / heating the pack and then the pack started charging at 7.5~8kW. Really what I was testing for was if the car warms the pack for just AC charging and it does. I assume it does the same thing when you set a "depart time" backing up and guessing how long it needs to warm the battery and charge it to the set point, but it seems to get the pack to about 50F.

Post #25 - The car will heat the battery to around 10C when AC charging. It will go higher, to around 20C, when preheating before a drive.

It appears that the Tesla vehicle when charging Level 1/ Level 2 will warm the battery pack to 50F (10C).

I am surprised that the Tesla vehicle started charging when the pack temperature was at 28F, thought charging when the battery is below 32F will damage the battery.

 

[Rocky_H]

It appears that the Tesla vehicle when charging Level 1/ Level 2 will warm the battery pack to 50F (10C).

That's different than what you said above, and you may have just typed something different than what you were thinking.

The pack started at 28F. SMT was showing it charging the pack with 3.5kW and the rear (only) stator running consuming 3.5kW as well.

Yes, this is what I expect, and I think is true. When cold, it will charge at a lower rate while ALSO heating and can increase current as temperature rises. That is very standard practice across lots of devices that use li-ion batteries.
This is what you said before, though:

The Tesla vehicle's battery management system will only charge the battery if the pack temperature is at or above 50F (10C). If the battery pack is colder than 50F the Tesla vehicle will first warm the battery pack before charging.

You said it will not charge AT ALL until it has finished warming up to 50 degrees, and I'm pretty sure that's not correct.

 

[pt19713]

I think the confusion is due to the charging source. If it's on a 120V/15A, the power source is not sufficient to keep up with the Stator motor demand, but on a HPWC, the 11.7 kW can warm both motors and still charge the battery.

 

[Rocky_H]

I think the confusion is due to the charging source. If it's on a 120V/15A, the power source is not sufficient to keep up with the Stator motor demand, but on a HPWC, the 11.7 kW can warm both motors and still charge the battery.

That might have been an explanation, except that the battery only needs to be a little above freezing to tolerate that low level of charging power--certainly not as warm as 50 degrees!

 

[pt19713]

I think everyone is making it more complicated than it should be. The icon simply lets the user know that the battery isn't at the ideal temperature for charging. If you want to get technical, which Tesla chooses not to for obvious reasons, yes, there are a lot of things to discuss. But still, simply it means the Stator motors are active to generate an inefficient non-motive waveform of heat to help warm the battery to that desired threshold. There's no quick, simple answer because of the variables, such as single or dual motor, and what the home charging source is and if it's greater than the draw to be able to send juice to the battery itself. If the battery pack is greater than 50F, this is a non-issue since the Stator motors won't be needed for the home charging.