First, you must determine your present house battery capacity. It will be found on the battery somewhere, but that is for a new battery. Second only half of that number may be safely used, unless you don't care about battery longevity.
Now you must determine how much wattage
each appliance and light consumes. Divide 1/2 your battery capacity by the total wattage of what you expect to operate/run to obtain your anticipated battery life while dry camping.
2000 Winnebago Ultimate Freedom USQ40JD
, ISC 8.3 Cummins 350, Spartan MM Chassis. USA 1SG, retired;PPA,Good Sam Life member."We the people are the rightful masters of both the Congress and the Courts - not to overthrow the Constitution but to overthrow men who pervert theConstitution. "Abraham Lincoln"