Battery isolator charge vehicle battery on shore power

jjrbus wrote:
I do not understand why I would add a solenoid? Wouldn't I add a wire between the 2 battery terminals on the isolator with an inline 12 volt
switch??

This is one way that is simple, another way that you probably have built into your chassis already, is to turn your key to ACC and that should combine both batteries. While plugged into shore power check both batteries to see if you get 13 plus volts.