Ford Dual Battery Setup

[carringb]

Originally Posted by Christopher Thwaites

Mike,
With the aux battery disconnected there is no power anywhere. No lights no starter no accessories. Same with the main battery.
From what you are telling me it appears the aux battery is strictly for extra cranking amps???? If not, is there a position on the ignition that allows use of the aux battery to power the accessory ports?
Is the wireing diagram you have available on line or do I need to buy a complete shop manual.
Chris

Your aux battery circuit is not connected. Read my previous post on enabling the circuit.

[carringb]

Originally Posted by Christopher Thwaites

Thanks to my local Ford service dept. manager who told me there are no relays in the system.
What does the relay do? Is just a solenoid that energizes when you turn the key?

Yes there is (at least on the V10), and yes it energizes with the key.

[Christopher Thwaites]

Battery Support, PN 4C2Z10769AA. List $145.20
Cover, PN 4C2Z10A687AA. List $65.49
Retainer,PN N808992S301. List $19.50 need 2
Hex nut, PN W701651S60. List $11.70. Need 2
Bolt, PN N605907S440. List $7.15. need 2
USA Part ?, PN N605920S439. List $4.55. need 4
hold down spacer, PN E7TZ10718B. List $6.24.
Spacer, PN 6C2Z10756A. List $12.45

There are 2 predrilled positions on the E350 frame rail, pass side. I added a 3rd battery to service my solar circuit. The frame has nuts already in place to accept the 4 bolts that hold the box. I already had the stock dual battery setup on V10s.
As you can see I paid the "oh look it's a stupid civilian" price. I used to be a Ford Parts counterman. I know about "list" and "what we charge people we know". The parts guy just looked at me when I asked if he had a better price. I didn't have time to screw around looking all over hell for a better deal. If you find a good deal go for it.
Also, the box will fit a standard size 27 battery. I had a 100 amp AGM 27. It is an inch too tall for the box so I had to modify the box....cut out the bottom and weld spacers in.
Have fun.

[Bones_GSXR]

On the Diesel are there 2 battery trays or 1 tray that holds 2 batteries? I am speaking of the frame mounts under the body.

[carringb]

Originally Posted by Bones_GSXR

On the Diesel are there 2 battery trays or 1 tray that holds 2 batteries? I am speaking of the frame mounts under the body.

Diesels have 2 batteries that are frame mounted. Both have their own "trays" which are more like a box. The diesel frame batteries are in parallel as starting batteries which is different from the aux battery setup on the gassers.

[Bones_GSXR]

So I could use two of these:
http://cgi.ebay.com/ebaymotors/ws/eB...K%3AMEWAX%3AIT
http://cgi.ebay.com/ebaymotors/ws/eB...K%3AMEWAX%3AIT
to replace my underhood Battery as well as adding a second?

[carringb]

Originally Posted by Bones_GSXR

So I could use two of these:
http://cgi.ebay.com/ebaymotors/ws/eB...K%3AMEWAX%3AIT
http://cgi.ebay.com/ebaymotors/ws/eB...K%3AMEWAX%3AIT
to replace my underhood Battery as well as adding a second?

Yes. Don't forget to select wire gauge based on distance. You may be able to just buy the diesel battery wire loom setup from Ford.

[Bones_GSXR]

Got 2 of the boxes from him for 20 bucks a piece. Cost more to ship them! I will have custom cables made once I have them mounted. Going to use Oddessy batteries as I have them on my Dual Sports and they are the toughest batteries I have found.

[dhally]

I just found out that my 2009 E250 5.4L has an aux battery mounted on the frame rail under the side door. In the owner's manual it states that the aux battery (if equipped) is NOT used for starting the van and is only connected when the engine is running. There is a sticker under the hood which warns that you have to disconnect BOTH batteries to kill all 12v in the van.

Question: does anybody know what type of battery it might be (too lazy to drop it out to find out), or where I could find that information? I'm planning to check out the wire size and relay ampacity to see if I might already have a house battery!

I'm still not clear on how a simple relay would work when the motor is started after running down the house battery. It seems that there would be a sudden large current trying to equalize the voltage between the two batteries...

[j.whitbread]

It is wired in series with the one under the hood. Dual batteries, always a pair. And when you turn the ignition key backwards to auxiliary, it powers the trailer wiring harness by itself. Does not use the main battery. Test it for yourself. Turn the key forward with a good draw from a trailer and measure load on engine battery. Then turn the key backwards to auxiliary and see what happens to the load split.