One would think it would be doable using a diode isolator (Schottky diode for low forward loss) - insert diode ahead of the avionics buss on current wiring set up. Then simply wire the new aux battery to the buss side of the diode. No back feed from the AUX to the system.

Thanks, Bumper, may tackle that this winter. Problem so far is I have not been able to identify what you would think of as a traditional power buss.. Several heavy wires come off the main switch, which is over by the side wall of the cockpit. Then large wires disappear deep under the instruments and under the panel. There is just a large mess of wires that come from deep under the panel. I think I will have to pull all the instruments and radio to be able to really get into the power buss.

I have been able to identify the negative buss.

Thanks

Kevin
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