I just recently (12/30/23) took delivery of a 3500 DRW that came equipped with a "BATTERY, AUXILIARY, 730 COLD-CRANKING AMPS/70 AMP-HR" and "DUAL ALTERNATORS, 220 AMPS PRIMARY & 170 AMPS AUXILIARY". I'm wondering how the aux battery is used/wired.

I am going to install several 12v "cigarette lighter" power outlets - don't even get me started about why the hell GM would yank them and replace them with 5v USB "charging only" power outlets!!

I could just pick up 12v at the fuse panel (with inline fuses), but I am considering drawing power directly from the battery (fused, of course). So ... does it matter which battery I connect to? The "main" battery is located on the passenger side of the engine compartment, while the aux battery is on the driver side.

Is the aux battery used to power some things and the main battery used to power others? Or are they just connected in parallel and both used to power everything? Or maybe some other arrangement?

Thanks

 

Use the aux. You don't want to run down your starting battery. There should be schematics on gmupfitter.com

 

@mountainmanjoe Thanks!