batteries went dead.

[Captain Newell]

The last time it was in storage for about 6 weeks the 2 house batteries and the engine battery went dead. I recharged all 3 at home, but now worry about a repeat. At this time I am disconnecting one of the cables for each system when I store the MH. When I touch the cable to the battery post there is a spark. This indicates to me a draw on the batteries. How do I measure that current to determine if it is excessive and will run the battery dead again? Should I simply add a battery isolator switch and turn it off when stored? The MH has a house battery connect switch which I turned off, but there is still a spark when I touch the cable to a post.