In my coach the second AC unit can run off the inverter. I only do this when I have the big engine running and it is a little to warm for just the dash air but no hot enough where I need to run more then 1 roof air. Alternator in coach is 340 amps and feel the roof AC unit is using around 120 amps 12V power while running. <br/><br/>I know my time is coming when I am going to...