I have a 2.5 KW Onan LP generator in my Lance. At half load, the fuel burn is about 1.5 lbs of fuel per hour. About 3 hours per gallon. So works out to be about 13 hours of run time per 20 lb tank. With our previous Lance which had a 7,000 BTU AC, I could run it with my Honda 2000 I generator. Much quieter and more pleasant to be near. Our Onan is loud but will start our 11,000 BTU generator if nothing else is turned on. If it is too hot to camp without AC, we find some place to plug in for the night most of the time. We use our built in occasionally to run the microwave, grind coffee, but we seldom use it. I have the Lance set up where I can hook it up to a 200 lb bottle if we need to live in it after a hurricane. This gives me about 125 hours of genny run time per bottle of propane.