[technobill]

Originally Posted by SFX Group

This layout (assuming the relay has a 5th pole to as a common between the 2 batteries so the switch over is "car batt to 5th" then "aux batt to 5th", however this design will result in the AUX batt never being charged.

If it was me i would permanently wire the AUX to the system and then relay the car batt to turn it OFF when the ignition is OFF, this way both are used when driving (and means both charging) then only 1 (AUX) is on when not, as the relay would disconnect the main battery.

Many Thanks

1) If you note the pictures on associated tabs; There are only four posts.
2) If by "5th pole to as a common between the 2 batteries" you mean a common ground, they would share the chassis common ground.
3) If by "5th pole to as a common between the 2 batteries" you mean a common connection between the positive terminals of the 2 batteries, that would be the relay itself. When the small post, to the left in the diagram labeled "This can be any 12 volt power source that is "live" when the engine is running" is supplying power, the relay connects the two large posts, connected respectively to the the positives of the two batteries and the second battery is charged through the positive terminal of battery one through the ground of battery two.
4) At what point would you "permanently wire the AUX to the system"?

Thanks for the speedy response.

Any pre 2007 GMT800 (Tahoe, Denali, Escalade) owners who have physically placed a second battery in the open area proximal to the fire wall on the drivers side?

Thanks,
Bill