House batteries not charging while driving
Got a new-to-me 1998 Chevy smb. It has 2 house batteries to run the fridge and other stuff. The batteries charge great when connected to shore power. However they donít charge while driving. I located the battery isolator smb installed under the hood and only 2 of the 4 posts have anything connected. It appears the previous owner bypassed the isolator to connect the starting battery directly with the alternator, hence why the batteries donít charge off the alternator.
My question is this: how do I actually test to figure out what is going on? I have a multimeter, but no idea how to use it or even which setting to set it on. Then I donít know what to touch the little probes to or what Iím looking for when I do.
Iím concerned the isolator went bad so they previous owner bypassed it, but he could have bypassed it simply because he didnít drive much and was constantly plugged into shore power.
Please help me learn!