Just the house battery of course. Running off the starter battery with engine just above idle it will run till I run out of gas.@ Sport Coupe, when you say "Mach 8 Plus 13.5k btu roof air (with easy start) will run off either van or house batteries but not for long"
You mean that when you say not for long ?
You're just talking about the house battery correct?
It will run on the the van alternator continuously ? ,,,,Or am i wrong , Thanks.
Now I need a simple way to bump up the idle a couple hundred rpm when parked.