Shine,
I have a 500, and I have had to look were I plug it up at. If I get into an ground fault outlet many times it will kick. The start load is when the unit draws most of its amps. When the heater elements fire up. Then the three fans that run all the time, and also the motor for the rotis. I feel even after you got it fired up the battery would go far. And with the new controller, I don't think it would like low voltage. I'm looking at the 3000eu, but haven't needed it yet.