An inverter that runs off the 12V battery in your car is very cheap. Get one, and an extension cord, and you have an emergency power source to cool down your freezer every few days.
This is the approach I am taking (bought inverter, will test it out next weekend). I don't think you can really run this off the battery (it will be on the order of 1000 watts): instead you need to have the car turned on and will be essentially running it off the inverter. So it's essentially an inefficient gas-powered generator that you already have on-hand and you need to make sure you have some gas in the tank.
That's one thing that's annoying in the current crop of EVs. Almost none of them support drawing power from the cars even though they have those huge batteries just standing there. I understand not wanting to add the cost of the inverter to every car but it seems it should be relatively straightforward to support external inverters that plug into the DC part of the CCS connector.
I think it's because the car companies don't want people meddling, draining their car batteries with poor power management and degrading the lifetime, and then coming to them and asking them to repair the damage.
Years ago, I installed a Tripp Lite inverter/charger along with two 120AH deep cycle marine batteries - all sitting on top of my fridge. I calculated that I can get a few days of power. Also have another 1500w inverter for emergencies. And I always ensure vehicles are complete full before any large storms. Losing all your cold food is expensive!
