[psomers]

There are several things that don't get cut off with switch. Carbon monoxide and propane detectors are two. To easily check for current draw disconnect a battery lead and just lightly touch lead to battery post. If any sparking you know there is current drawn.
To keep from draining my battery during idle time is disconnect negative battery at frame and insert 500 amp knife switch to ground.

PS: Before drawing arc at battery make sure it is well ventilated as a charging battery gives off hydrogen.