Factory auxiliary battery

[74Chev]

I just got finished re-connecting the factory aux. battery setup in my 79 Jimmy. When I got the rig it had an aftermarket isolator, and wires,and tape, and mor wires, and you know the rest. It is a trailering special model with the relay switch on the driver side fender, getting power from a browd/wht wire from 15 amp fused on the panel. It appears that the relay disconnects the aux. battery from the main junction block on the upper firewall when the key is turned off or to acc. thus isolating the aux. battery and anything hooked to it, and not allowing it to suck juice from the main starting battery. Please correct me if I am wrong. Now a few questions.
Should high draw accessories be hooked up to the auxiliary battery, or main battery.

If the main battery were drawn down would the aux. battery provide a charge to the main battery once the key is turned on and the relay switches back to connecting the aux. to the main junction block?

If I did hook up a winch, etc. to the auxiliary would it draw both batteries down together if the engine was ON (relay closed) and the load was high?

Thanks for any help

 

[imiceman44]

I don't know if all brands are the same, but the good isolators do just that, Isolate, they have diodes in them to prevent one to drain into the other. The ignition feature is to give the secondary battery access to the alternator.
Actually you will not drain both batteries unless the engine is running and your winch uses more than what the alternator is giving which is the case most of the times.
They only get conected when the engine turns and the alternator starts charging.
But that is the way the good one work, no idea what you have.

 

[Grim-Reaper]

I'd Run all the high draw stuff aff the AUX battery. Leave the vehicles stock set up alone for just the truck. You can use a Ford Solonoid and make a self Jump feature back to the main battery pretty easy and cheap.

 

[502Burban]

Any chance you could post some pics of your factory aux battery mounting brackets? I'm wanting to add the factory setup to my Suburban and want to make sure that I get all the necessary parts. Any photos you can supply would be a big help.

Thanks,