Average compressors take 2 - 3 hp to run once spinning, add more HP for initial start, and to be efficient they need to run 1200 or more rpm. Now you need to increase the air flow through the condenser since you won't have the speed of the vehicle to help cool the charge. So add 30 to 40 more amps of power for a big electric condenser fan, 5 or so more for the evap fan, and few more for the clutch. If your system uses the clutch cycling on and off to regulate the temp, now you have to adjust the compressor motor speed as it unloads and loads as the system cycles other wise the rpm will jumping quite a bit. Three group 31, 800 amp batteries should run it for a little while, thats about 250 pounds of batteries.
