Ford Dual Battery Setup

[FarmerFrederico]

Originally Posted by carringb

Have you cleaned the terminals on the aux battery? I had a similar problem once and that's all it was.

They are clean as a whistle. NAPA guy said some of these isolators only kick on when a certain amperage or voltage threshold is reached. I'm just going to trust that it works since I have a charged battery unless someone here can say that welding on the frame during 4x4 conversion would have shorted out the isolator since the auxiliary batter was never disconnected during that time.

[Photoventurer]

I recently purchased a 2000 E350 former ambulance with a 7.3 diesel that had been partially converted by the young man I purchased it from. It was equipped with dual alternators and dual batteries. I can't for the life of me figure out why he did it, but he got rid of the auxiliary battery and all the wiring. I had been thinking of replacing it and using it as the house battery. This thread has been a great resource! Thanks for all the great posts!

[carringb]

Originally Posted by Photoventurer

I recently purchased a 2000 E350 former ambulance with a 7.3 diesel that had been partially converted by the young man I purchased it from. It was equipped with dual alternators and dual batteries. I can't for the life of me figure out why he did it, but he got rid of the auxiliary battery and all the wiring. I had been thinking of replacing it and using it as the house battery. This thread has been a great resource! Thanks for all the great posts!

Keep in mind the "auxiliary" battery in the V10 is not setup the same way as the dual battery in the diesels. The 2nd battery, on the passenger frame rail, is simply in parallel to the under-hood battery, and both are used for starting (2 really are needed if its cold enough to need glow plugs).

That said... most Ambulance builders did add 1-4 "house" batteries, setup with an isolator, usually mounted on the driver's side frame rail, and often with a battery access door (looks a lot like SMB's propane access door).

[Photoventurer]

Thanks carringb! I did realize that the diesel is not the same as the V10. I'm sure the ambulance builder did have it set up with an isolator because I found one in a box of stuff that came with the van. Unfortunately, the isolator and a couple of wires are all that's left of the auxiliary battery setup. The ambulance outfitter is a company called Osage. I can tell by the remnants of some of the wiring that they left the auxiliary mounted on the passenger side frame rail so no handy access door for me. You are right about needing 2 for starting, I have noticed it as the nights have turned a little cooler lately. Thanks again for the info.

[TwoVans]

Just picked up a 2014 V8 which came with dual batteries. They are wired from the factory in parallel. It would really be nice to separate them since two for starting is really overkill.

Has anyone out there tried this? In a perfect world, the 12 volt outlets would be powered by the non-starter battery to protect me from draining the starter with my ARB fridge.

Thanks!

[daveb]

Originally Posted by TwoVans

Just picked up a 2014 V8 which came with dual batteries. They are wired from the factory in parallel. It would really be nice to separate them since two for starting is really overkill.

Has anyone out there tried this? In a perfect world, the 12 volt outlets would be powered by the non-starter battery to protect me from draining the starter with my ARB fridge.

Thanks!

Not sure. Where is the second battery located? I thought that Ford already had some kind of relay in the loop if the 2nd battery is on the frame. If not I'd think just installing a separator and third battery might be a better choice especially if the starting batteries are under the hood. Depending on the load, you'd have to factor in the voltage drop on a long run which would also determine the size of the wire for a dedicated 12v outlet. I'm not sure about how the stock 12v outlets are routed but they might be a nightmare to separate if that's what you're after. The closer your aux battery is to the fridge the better. I'm wondering if you could use the trailer power wire off the trailer harness as the charging source and just cut in a separator and 3rd battery. I just don't know it's a non switched wire or what that trailer harness can support amp wise and/or voltage loss way back there... maybe Carringb or Scalf77 could give you a better answer.

[TwoVans]

At one point I ran across the year Ford started wiring them in Parrallel vice Starter/Aux. I want to say it was after 2010, but I'm just guessing.

Anyway, one is located under the hood. The second is on the passenger-side frame where the front of the two are located on the 6.0L. The holes appear to be on the frame where the rear battery box was on my 6.0L. Easiest option might be to just take advantage of that spot to add a third...

This van was ordered with the up-fitter switches which added the heavy-duty alternator and dual batteries.

[Jolly705]

starting up an old thread, what size marine battery is 6.5" tall? I am having trouble finding one local in SLC. I have looked all over the place. This is the battery box I have and want to mount on the frame:

Ford Econoline Eseries Van Box Truck motorhome camper Battery Box E350 E250 | eBay

Thanks in advance!

[Bellpilot]

Group 27M deep cycle battery will fit perfect in the battery box.

[Jolly705]

According to the Internet 27M are too tall?