I copied this from my Intellitec 100 amp Battery Disconnect manual
"Battery Disconnect is an easy-to-install system that will allow RV owners to disconnect coach and chassis batteries with just the touch of a switch. With BatteryDisconnect, the owner can be sure the batteries are disconnected when his RV is not in use or being stored off-season. It is conveniently located inside the RV, and it's all remote.
The heart of the Battery Disconnect system is another Intellitec invention. A latching relay, capable of carrying heavy coach currents, draws power only when switched on or off; yet, it requires no power to stay open or closed
. This sturdy relay is sealed against the environment and is designed for the toughest use."
So I think its main function is convenience. When the switch is off the house battery(s) are disconnected. My battery monitor panel runs off of it as well.
I would have guessed that it drew some current when on but, according to the above, it doesn't. I looked at the service manual. It uses a magnet.
g1g - maybe yours doesn't draw power when open or closed. Do you know what brand it is?
You could have a manual cut off switch but a Battery Disconnect is more convenient especially if located near a door.