You will need to shop for a car inverter. Find one that is at least 1,500 watts, and it will help you power your refrigerator for up to five hours—usually without damaging your car battery. Considering how much food we keep in our refrigerators, a $200 car inverter is a bargain!
I looked up the page and it gets worse.
Another source says they hold around 700 Wh. So not even 30 minutes actually
At least they don't run constantly?