Vikes79
SKOL!
Lifetime Member
It was a generalization on the isolator.This is incorrect.
The isolator doesn't push amps to anything. It does, depending on conditions and voltage of each battery, connect the two batteries so they can share a common charging source. Also, to a point, it will allow one battery to "assist" the other that is under load, but if it is the main helping with aux load, it will stop helping in order to prevent over discharging of the main bat.
The dual voltmeter requires a ground. It also would need a + battery connected to one of it's two inputs with some reasonable voltage - - it would then display that voltage. If another battery is connected it would display that voltage. So long as there's a ground applied, either battery will light its respective display.
Thus, if you know one or more batteries are good, and both the voltmeter displays are off, then you would suspect the ground is bad. Note that most installs have the ground applied by a relay that is powered by key-on positive voltage. If for some reason the display is completely blank, then and easy troubleshooting step is to use a scrap of wire and apply ground to that meter input terminal.
Let me know how well your multi meter works without a battery….