Have a new Nt 28 brs. We are in a seasonal campground and use a generator for power. I have four charged batteries to power the trailer. I use one battery a night but at times I use the generator for power for the TV, microwave .If the battery runs out of power the furnace will shut down. With my old trailer I could run the generator with a dead battery and get power to the furnace.The Rv service man said you must have one good battery to run the furnace. I can put two batteries together and keep them charged with my solar panels if need be.