Roy,
That long post of yours earlier in this thread, with diagrams, is excellent!
It hints at a subtle but very important point related directly to the OP's original issue/question: WHERE in the RV's internal 12V circuit a monitoring voltmeter is located is VERY IMPORTANT. A voltmeter should NOT BE LOCATED "far from" the RV's batteries such that loads (lights, propane monitors, refrigerator control boards, etc.) create voltage drops in the wire run that a voltmeter is connected to - hence making the voltmeter read too low and also making it's readings appear to vary a lot as little RV loads along the wire run come-on or go-off.
The best way to have a voltmeter monitor the RV batteries is to have it connected to the batteries either as close to the batteries as possible or connected to the batteries using large size wiring - not because of current flow through voltmeters (which is ultra-low and not an issue) - but because the currents from other loads can depress the voltage readings on the voltmeter. These voltage readings then DO NOT represent what voltages are actually right on the coach batteries at that point in time.
I violate what I said above with my battery monitoring voltmeter right above the dinette. It's readings indicate an average of about 0.16 volts lower than actual readings made right on the coach battery terminals. I have a digital four-decimal-place voltmeter - by the way DO NOT use a three-decimal-place voltmeter for keeping an eye on your batteries - plugged into a convenient 12V all outlet there above the dinette. I know about this voltage drop error coming from the circuit where the voltmeter is connected and mentally take it into account whenever I glance at the voltmeter.
