[Latitude 28]

Doug,

If I read your comments correctly, and you know reading is not a strong suit of mine, then you are looking for two things. One, to be able to merge the chassis and house side for emergency start. Two, to be able to charge the house side safely without frying the alternator.

If that is correct, it may be even easier than you proposed. Here would be the steps.

Determine if the merge solenoid is automatically closed when the ignition is on. If so, disable that feature. There may be multiple trigger wires to the solenoid. If so find the one that is hot when the switch is on. If the merge has other triggers then they may be the dash switch activated ones. If so, you are home free.

Second, determine of the heavy cable terminals on the merge solenoid is house, and which is battery. Label for posterity, or when you reach my age and have CRS. If you want to use a DC to DC, you would simply wire it across the two heavy terminals. Of course it’s one directional so you have to know which side is house and which is chassis.

One thing to keep in mind when wiring up a DC to DC setup, or any other connection between house and chassis is you may not totally disconnect the voltage with the manual disconnects. It is always good to confirm with a Voltmeter that the circuits are dead.

Doug, In this scenario that Richard talks about, if you would want to charge "Bi-Directional" this DC to DC charger can do the trick....https://www.sterling-power-usa.com/SterlingPower12voltto12volt-40ampbatterytobatterycharger.aspx