If you have a 3 way fridge, which sounds like you do, it can draw more power, 15 amps, than your truck may be supplying to the battery. If that is the case, you may want to load up the fridge before you leave home and make sure everything is cold. Turn the fridge off before you leave and everything will stay cold for a number of hours. Switch it on to LP when you get to your camp spot. The control board on the fridge draws some all the time, also if you have a DSI water heater it draws some power for the control board and the ignition. The LED lights draw very little amperage and shouldn't be a worry. The jacks would draw a fair amount but that is for a short period of time. The furnace fan will draw the most amperage while you are over time. I'm thinking you arrived without a fully charged battery because of the fridge. Charge lines are notoriously undersized on vehicles for unknown reasons, a larger gauge wire would help. if you have room, add a second battery.