Jon R
Senior Member
My new truck finally arrived, so I'm now able to look at the factory dual battery arrangement. This truck has a single 220 amp alternator (base is 175 amp). I thought I'd describe it in case it's useful to someone in the future.
The battery isolator appears to be a simple relay that is part of the fuse housing on top of the aux battery, and it connects the batteries only when the engine is running according to the manual.
The main battery has a fuse assembly on top of the battery with the main fuses, and it includes a spare fused 1/4" post with an 80 amp fuse installed. I plan to connect my 6 awg positive wire to the camper's DC to DC converter to this post (I may reduce the fuse to 60 amps). The negative battery connector has a single unused 1/4" inch post on it. There does not appear to be a conventional negative bus bar anywhere under the hood. I plan to use the post on the negative connector for the 6 awg negative wire to the camper. I plan to run the camper wires in split plastic conduit across the top rear of the engine compartment alongside the factory bundle and then down and back along the left side on top of the frame attached to the existing factory bundle. The exhaust is on the right side, so the left stays cool, and that's where it needs to end up anyway at the camper. I still haven't decided what connector to use at the bed, but I'm leaning to a fixed SB50.
The auxiliary battery is connected to the main battery by a 100 amp fused (at both ends) positive wire that runs through the isolator relay. The aux battery fuse housing has a 30 amp fused post that connects to the trailer/camper connectors in the bed and at the trailer hitch. It has a spare position for one more fuse and post in the plastic housing. I expect there is a GM part that can be bought to add to the fuse block in that position.
I don't plan to associate the truck auxiliary battery with the camper electrical system. I plan to connect to the aux battery a 12 volt cigarette lighter style connector for a portable fridge/freezer in the back seat area, and eventually hope to power a permanently installed air compressor from it as well. Hopefully I can obtain the GM part to add the post and supply those items. I hope to have it all looking like factory work when I'm done.
The battery isolator appears to be a simple relay that is part of the fuse housing on top of the aux battery, and it connects the batteries only when the engine is running according to the manual.
The main battery has a fuse assembly on top of the battery with the main fuses, and it includes a spare fused 1/4" post with an 80 amp fuse installed. I plan to connect my 6 awg positive wire to the camper's DC to DC converter to this post (I may reduce the fuse to 60 amps). The negative battery connector has a single unused 1/4" inch post on it. There does not appear to be a conventional negative bus bar anywhere under the hood. I plan to use the post on the negative connector for the 6 awg negative wire to the camper. I plan to run the camper wires in split plastic conduit across the top rear of the engine compartment alongside the factory bundle and then down and back along the left side on top of the frame attached to the existing factory bundle. The exhaust is on the right side, so the left stays cool, and that's where it needs to end up anyway at the camper. I still haven't decided what connector to use at the bed, but I'm leaning to a fixed SB50.
The auxiliary battery is connected to the main battery by a 100 amp fused (at both ends) positive wire that runs through the isolator relay. The aux battery fuse housing has a 30 amp fused post that connects to the trailer/camper connectors in the bed and at the trailer hitch. It has a spare position for one more fuse and post in the plastic housing. I expect there is a GM part that can be bought to add to the fuse block in that position.
I don't plan to associate the truck auxiliary battery with the camper electrical system. I plan to connect to the aux battery a 12 volt cigarette lighter style connector for a portable fridge/freezer in the back seat area, and eventually hope to power a permanently installed air compressor from it as well. Hopefully I can obtain the GM part to add the post and supply those items. I hope to have it all looking like factory work when I'm done.