I have a Powerline HEHR 22-27 (PLI160-20) ISOLATOR I'm trying to figure out how to test. My coach batteries was overcharging, boiling, fuming etc and we feel like the isolator is the culprit. This has 3 large terminals on top. Something that is confusing me is the label on the side. It say: 1. main bat: 2. Aux bat: A alt: and 3 aux bat. It seems to have labels for four terminals...but there are only three.
Can someone help me??
Gary