This post is in response to the question that gets asked on a regular basis which is how do I install a second battery and connect it so I don't discharge my starting battery.
For me, the automatic charge and disconnect action of the solenoid is important as I don't want to have to remember to move a switch of some sort for charging or starting. Guaranteed I'd forget at the worst time.
Basic schematic of my configuration.
My RV battery is mounted under the hood but could just as easily be in the camper. The heavy wires are the ones shown in the schematic. The light ones are the feed to the camper fuseblock.
My solenoid is mounted to the engine block and therefore if it was a three terminal type, wouldn't require a separate grounding wire as shown in the schematic.
The leftmost large connection leads to the RV battery positive terminal. The left small connector goes to the fusebox and is connected to a feed that is on only when the key is on. The right small connector has a wire going to the engine block. The right large connector goes to the alternator positive wire. Note that I've connected this wire to an existing junction in the alternator supply wire instead of connecting directly to the alternator as shown in the schematic. This was just more convenient for me.
The wires from my RV battery run under the vehicle and up to this plug in the side of the box. Note that only two of the four connectors are used. This wiring is not shown in the schematic.
This connector goes from the camper to the plug in the box. This wiring is not shown in the schematic.
2001 GMC Sierra 2500 SLE Short Box 4 door Extra Cab
6.0 Vortec, 4L80E Auto Trans, 3.73 rear. 4X4. Timbrens, Rancho 9000's. Hidden Hitch front and Happijac rear tie downs. 1985 Frontier Camper.
Member/Editor of Victoria Motorcycle Club and ASHRAE
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