It's only a maintainer designed to keep the battery charged that is not receiving a charge from either the alternator or inverter, if charge is not happening on either then it will not try to charge . If you notice in the original picture there are three small boxes side by side, the one in the middle is marked isolator lockout, the one to the right is not marked, but your schematic signifies that it is a slide lockout. Both of these are connected to the LE415 through a ground bus bar, the groun