I am going to Fraser Island in February and was curious to know how many amps my fridge drew from my aux battery.
Searching thebay I found a little power meter thing that could calculate amps,watts battery voltage etc.
I hooked it all up and started timing the 24hr at 730pm,the fridge internal temp was 29degrees,the thermostat set to 2 degrees.
As a worst case scenario I did the test with an empty fridge cause I know it takes more to keep cool empty so it would leave a little buffer in the real world(half beer half food)
After 24hrs on a hot day(34degrees,still 30 at 730pm) the draw was 31.55a/h,probably a bit more than I expected but gives me a good indicator for battery preservation and probably explains why my last 100ah marine battery lasted 12months.
Hope this is helpful