My 1969 Avion C-11 now has two batteries. I can run the furnace all day and get by for a couple of days before I need to charge them. Having said that, I should be charging them every day for a few hours. I have an older Yamaha 1000 and a new Honda 2000i. The Yamaha will serve my needs just fine, including running a 5,000 btu AC. The Honda is totally unneccessary with my current application since my charger is a small Schumacher Ship-N-Shore that runs fine off of the 1,000 watt Yamaha. Since I have an Avion 34' trailer also, the Honda makes more sense. It all depends on the size of charger that you have and what load you are going to put on the generator. If you are never going to use over 750 watts, get the 1000. If you are going to run over 750 to 800 watts, or more, get the 2000.