Dual Mode should only energize when the ignition is on though.
Again, I think this is the key I was not understanding before.
All the solenoid does is gang the two batteries together, MOM or DUAL it is the same.
The difference is where the power source comes from to energize the solenoid.
With MOM, it comes from the house batteries.
With DUAL, it comes from the ignition switch (engine batteries).
The reason is because in MOM it is assumed the engine battery is dead. And by making the switch spring loaded, you can't permanently gang the batteries together and pull down the house batteries.
In Dual, you want to charge, so the rocker "sticks" in that position, but you don't want to use your engine battery as a house battery (and risk draining your engine battery) so the solenoid disengages when the ignition is off, thus isolating the engine battery.
Before this thought exercise, I was assuming there were two different ways of achieving the ganging together of the house and engine batteries. In reality, there is only one way. The Charging Solenoid gangs them together. The only difference is who is energizing the solenoid.
Steve
