If I turn off the power,isn't that good enough!
You don't indicate your coach, so hard to know how you are wired.
On many coaches, the house battery disconnect only disconnects 12v devices, not the inverter/converter. So if your inverter is left turned on, it could suck your batteries dead in a number of days. You also could have what is called parasitic drains, where the mfg has wired things directly to the 12v buss and are on all the time (for instance, possibly your propane/smoke detector).
To determine for sure, get a current monitoring device to put on the battery cable and check to see how much current is being taken out of your batteries when you think you have turned off everything.