Originally Posted by frede
When I measured the voltage across both sides of my Isolator/aux start/charge solenoid with a digital voltmeter it showed a 1.23v differential regardless of the auxiliary start switch position. I changed the relay and it now reads 0v when the auxiliary start switch is pressed.
The zero volt reading tells you the solenoid is operated and both batteries are connected together. You can also verify proper operation if you have voltmeters inside the coach measuring your house and chassis batteries. When the switch is operated or the engine running with both batteries bridged, you should see identical or near identical voltages on both batteries.
The charge solenoids fail frequently as the contacts get pitted from arcing when çonnecting or disconnecting. You might want to consider carrying a spare particularly if you have a residential fridge and want it to operate when travelling with the alternator charging the house batteries to feed the inverter. Good luck,