Already what happens. GM and Tesla use pumped liquid glycol for heating/cooling and some other companies use refrigerants.

Interesting. I did not know that. I always figured they must need to manage heat, at the bare minimum by preventing huge draw for extended periods of time. Do you know where they radiate the heat, given that most Teslas don’t (to my eyes) have visible grill vents?

All Teslas have a grill in the front, it's down low. The battery cooling system is shared with the cabin cooling system.

You only need to do that when charging the battery.

Oh, do the batteries not heat up when discharging quickly as well? I know next to nothing about battery chemistry, but for some reason I just intuitively assumed they did. RC aircraft batteries can certainly catch fire if something causes them to discharge extremely quickly.

They discharge slowly during driving, unless you floor the acceleration while driving up a slope, but I'm sure there are some kind of limits in place, to prevent the user from draining an unsafe amount of power from the battery.