dual batteries?

[doc1976]

I have a 69 custom cab, and I appears to at some point had a second battery tray installed. I am not familiar with the purpose for this. the second tray now has the radiator overflow reservoir installed there, but there is still a tray there and some odd wiring there too. by odd wiring, I mean there is what looks like a spring with wiring attached to it along with some other wires. can someone give me the rundown on the purpose and wiring of a dual battery system?

[doc1976]

let me also add that I think it may have something to do with a camper trailer maybe? the truck also is wired for a 7 flat trailer connector.

[HIO Silver]

The purpose of a dual battery system is to provide auxiliary power to heavy loads like offroad lights, winches, subwoofer amplifiers, refrigerators, and bed camper and camper trailer units (water pump, fans, interior lighting). With the engine running, a constant duty solenoid engages and connects the auxiliary battery to the main charging system so that it recharges. With the engine off off, the solenoid disengages thereby isolating the main battery from the auxiliary battery. This is so ya don't kill the main battery for starting and general operation.

Some systems have an override switch allowing you to self-jump. That comes in pretty handy if your niece leaves the ignition on the entire time yer tailgating and attending a NASCAR race. As you can see, I speak from experience.

Here are write-ups/pics on dual battery systems;
http://www.4crawler.com/4x4/CheapTricks ... ries.shtml
http://www.fullsizebronco.com/forum/sho ... p?t=198774
http://www.ford-trucks.com/forums/10635 ... h-pix.html

[doc1976]

would this be factory for 69 or installed later? Sounds like maybe a camper special option? although mine does not have camper badges.

[1972hiboy]

the camper special came with little odds and end like the pre-wired camper plug down on the frame rail about midship and some f350 front end parts and usually a heavier gvwr. agreed the dual battery is for the camper power. or anything else you want. I just put a dual setup in my truck for that very reason.

[doc1976]

thanks for the response guy's. I don't remember seeing a solenoid or isolator, but I think I will chase the wiring that is there, and consider getting the second battery set up at a later time, the camper shell I use now does not need power. thanks again

[Kurt Combs]

I had a dual battery setup in a VW camper, and it was really cool. I could run my stereo until the battery died and still start the engine. I used a deep cycle battery on the auxiliary side.