Re: flat batteries
Do you have a 12 V battery disconnect switch? If so turn it off when you are not using you RV. The clocks and some other small appliances will still draw power if the batteries are not turned off.
If your batteries are turned off and you are still losing power, you probably have hard wired smoke, propane, carbon monoxide detectors wired into your 12 V system. Either find the fuses and disconnect them or just disconnect the batteries from the RV circuit. I had the same problem and couldn't figure out why after turning my battery disconnect switch off, I was still slowly losing the charge. I finally discovered my detectors were wired direct to the batteries, by-passing the turn off switch. I guess they keep the detectors on just in case you are in the RV with the 12 V turned off. Safety.