Re: Turining off battery power
Battery disconnect switch is best. That way it is a quick shut off wether you are storing if for a few days or weeks. I used to mess with disconnecting the cable, but it is nice to just switch it off and on. You will never be able to shut down all phantoms loads like the lp detecter and such. Here is the switch I have. These run about $25 to $30. I thought I might like being able to shut off one battery or the other, but I honestly don't use that feature. You can get simple cutoff switches that attach directly to the battery terminal for only a few bucks.
Blue Seas Battery Switches E Series
Economical and versatile series of switches, 4 options to choose from. Versatile set of switches can be mounted flush or surface mounted. Accepts up to 4/0 battery cables. 350A Continuous Rating - 45% higher than standard switches
Luminous label for low light reading
Ignition protected - safe for installation aboard gasoline powered boats
Meets UL 1500 and SAE J1171 ignition protection requirements
Make-before-break contact design allows switching between battery banks without power interruption (9001e and 9002e only)
Meets all American Boat and Yacht Council (ABYC) requirements for battery switches
Some more samples
Battery Disconnect Switch