I use a terminal disconnect switch on my engine and house batteries. I got cheap ones from Harbor Freight for a few dollars each. Being cheap, the plastic knobs spun on the brass insert, spinning the knob but not the brass piece. I fixed this by cross-drilling them on my drill press, drilling a hole through the knob and brass insert, and then pressed in a piece of a nail to pin the parts together so that they could not spin independently.
They work great.
I use them because I was getting parasitic loss that was killing the engine battery, and rather than hunt down the electrical problem I just disconnect the battery when I put the RV in storage.
Also I hard-wired a propane/CO detector to the house battery and it would drain the battery over time if not disconnected.
