I have a 2001 E350, v-10 with the optional auxillary battery. My problem is that if I leave a light on by mistake, the main battery goes dead. If I check the aux. battery, it has a full charge. How is the aux. supposed to work? There is a normally open solenoid mounted under & to the right of the main battery. There are 2 red wires going to one terminal. One wire is marked "main battery". The other terminal has one yellow wire attached. There is a purple wire that powers the solenoid. It is normally off. When the igntion is on it is powered. Should one of the red wires be tied to the yellow wires post? I am wondering if it was wired wrong at the factory. Does anyone have a manual with a schematic? The van is out of warranty. Thanks.

 

Do you have a owners manual? If not, you can go here

www.helminc.com

and buy one that might explain it. Most people use aux batteries for camping, and other things. They don't want these type of uses to run the main battery down so the vehicle won't start and leave you stranded. That's usually why they are charged together, but the loads are kept seperate on each one.

 

In this case, the load is the same. I don't know if the main battery is isolated when the igntion is off.

 

Aux batteries are designed for Campers, Trailer's & Winches.

The isolator is doing it's job.

I always carry a set of booster cables > just in Case< something happens to the main battery.

 

This isn't really an auxillary battery. It is what Ford calls Dual Batteries. This is just a E350 van that I use for work. I don't really know how they are wired or how the system is supposed to work. All I know is that if I leave a light on the main battery goes dead, I can't start my van & the other battery still has a full charge. Does anyone have a schematic or an idea on how the factory system works.

 

Because of the way it's wired, it is an auxillery battery. It should be fairly straight forward to parallel the two and make them duel. Basically, you remove the soleniod and hook the batteries red to red, black to black; HOWEVER, probably your best bet would be to check out a diesel see what they've done, if you really want duel.

You know, you could leave the auxillery battery arrangement connected, then run your lighting, radios, ect. off the the spare. That way, if you do forget to turn something off, the van will still start. It's not good to drain a battery like that, but at least you aren't stranded or have to pull out the jumper cables.

This is how I used to wire our old gas powered work trucks. When we went to diesel, they used duel batteries to fire up the power hungry glow plugs, so that wasn't an option. Instead, I installed a battery saver, (a basic timer and relay - doesn't cost much). You can jumper them to turn off lights and radios, ect. after a certain amount of time after the engine stops. (For anyone that like to tinker, you can DIY for about $10 in parts at Radio Shack.)

Just giving a couple options, so the jumper cables can go back to collecting dust...