A heater in a Tesla will work for approx. 3 days on a full charge if the car is not moving:
Ira J Perlow
, Tesla Model Y, grid-tied Solar PV owner, Electronic Engineer
Answered 9 months ago ยท Author has 2.7K answers and 3.5M answer views
How long can a Tesla run its heat if the car is not moving?
The answer is about 72 hours (3 days). Of course you may get different numbers depending upon whether you have resistive heating or a heat pump in your Tesla and the ambient temperature. See my answer below
Better to have a 12V(?) electric blanket in the car.
Heat the human, not the car.
Gitcha onea them thar Ford trucks that can power yer house when the lights go out!