[rickst29]

I haven't made it pretty yet (aligning within a box, or attaching Relays to the vertical MPPT Mounting post on the left. But here's photo, and I'll explain it:

The blue Wire Nut contains red wires. #1, the Bargman "Trailer Charge" cable from under the Fridge (a high-power wire, up to about 280W ~ 11.7A @ 24V ). #2, a low current "Jumper" into the 24V Relay on the left, as the coil switching "+" lead. And #3, a high current wire Delivering power to the MPPT "Solar Input +" on Relay #2.

4 wires on Relay #1 are:

1. Coil switching "+" (the jumper from Blue Wire Nut);
2. White Coil Ground. (all Ground wires connect to "Battery -" on the Solar Controller);
3. "12VDC" pulled from "Battery +" on the Solar Controller; and
4. Output to the second Relay "coil +".

The purpose of Relay #1 is to detect when 24V is present on the Bargeman, and then Deliver 12V coil switching Voltage into Relay #2. Nothing more. All 4 terminals are extremely low power.

The 5 wires on Relay #2 are:

1. Coil switching "+" (the "switched output" from Relay #1, at battery Voltage or nothing at all;
2. White "Coil Ground."
3. A shared OUTPUT LEAD to the Solar Controller.
4. The Solar Power Input from Panels (In perfect conditions, mine would be 5.3A @65V, although the MPPT won't accept full power.) This one is connected to the Output Lead (and Solar Controller) whenever the Coil does not have 12V power.
5. The 24V "power input" from the Blue Wire Nut.

When I activate the "Zombie" Switch in the 4Runner, a 12V coil switching Voltage is put into the second Relay. The Relay switches the connection from the Genuine Solar Panels to the 24V "power input" lead.

- - - - What Happened to the 3rd Relay ? - - - -

The Job of the 3rd Relay was to connect the Bargman, running at "regular" 12V, into the TM "12V" electrical system. But I realized, as a I reached for the Relay, that it's a slightly bad thing to ever make that connection if the TV is capable of "24V or Nothing" operation, and you always remember to flick the Zombie Switch when it's dark.

Here's why: If The Trailer batteries are seriously discharged, and "Bulk Mode" charging is desirable under good Solar Conditions, the connection reduces the Solar Battery Charge Voltage by "leaking" power back to the Tow Vehicle. (And of course, the TV doesn't need that power at all.)

If Solar conditions aren't great, just flick the Zombie Switch, and connect the TM at a Voltage which is sufficient charge batteries. Let the Solar Controller make al the decisions, all the time.