Has anyone out there an understanding of the battery management system (BMS) in a 2023 MYLR? There didn't seem to be a definitive answer to my question about our hot garage and if the BMS will protect it over the long haul.
AFAIK, no Tesla manages the battery temperature when the car is asleep. To do so would drain much more battery. People who have car monitors say the car only draws around 5W when asleep, and there is no way that is possible if there was any active cooling or heating going on (or even a fan running).
That seems to match my own observations: when car is left alone for a long period like days or weeks, it drops only around 1 mile of rated range every day or two; in my Model 3, the rated range is based on ~210Wh/mi, which means 210Wh every 24 hours to 48 hours which works out to an average of ~4-9W.
The temperature however is managed when car is awake (which the car may occasionally wake to recharge the 12V/16V battery; people say every one or two days for the 12V batteries).
That said, it's not a big deal as long as you keep the SOCs low. Batteries degrade the fastest at high temperatures and high SOCs.
Even if you keep the car plugged in, it actually will go to sleep after the car reaches the target charge. However, as the battery drains down to some point, it will wake up to top it back up to the target charge. This is just what I observed personally.
You would have to weigh the benefits and risks of leaving it plugged in. If you need to use the car immediately after your return, you may want to keep it plugged in (especially if you might accidentally leave a feature on that might keep it awake and drain the battery). If not, you may leave it unplugged, which reduces the risk of issues while you are gone (like a bad connection that might lead to a fire).