Isolator installation is easy and rewarding. See dual battery Installation section first, if you plan on installing  a selector switch into the system.

Diagram #1 depicts an Isolator installed on a unit with an external regulator, that utilizes an external sense will.

Diagram #2 illustrates a system with an external regulator that does not have an external sense will. The wire between Batt 1+ and B1 Isolator is optional

Diagram #3 As you saw in diagram #2 , B1 terminal is optional, so a third battery could be installed on this system.