These relays from a JY ambulance will isolate my aux. battery. But having 2 will increase the current the aux. can pass to the main for the winch. The fuse & small wire will allow me to use the aux. batt. to activate the relays if the main is totally dead.

Eventually, I'll build a bracket to mount them near the main battery, and tie the fuse holder in to the engine bay harness. The loose red ring terminal will go to the battery side of the starter relay. A long cable will go with the OTHER (2-ringed) cable and run back to the aux battery, where the power inverter wiring will also connect.

See also:
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Owner caption March 2012 · Photo 4245 of 5000