A Tesla can run its heater for about 72 hours.
If they left home with a good charge they'll be good for another 50 or 60 hours.
I did some checking and this is not correct. The Tesla battery can run the heat for about 7 hours if nothing else is operating. When the battery gets to 20% the heating / AC shuts down. If anything else is running like the traction motors the batteries go south much quicker.
