I have a Multiplus II 2x120 in my RV, and it is rejecting the shore power input (“mains on” blinks and it clicks off). I have a 50A EMS and it shows 123V on each leg with no errors. I am using a 50A extension cord I have used many times before. Any ideas what could be the problem?
You mention 50A and shore power, but are you connecting to a generator or mains power? 123V is a little high and I wonder if you have accept wide voltage range enabled or not. Can you post your settings on the MultiPlus on the general, grid, inverter, and charger sections?