Dual Factory Aux Frame Mount Batteries and Cable?

[1der]

I need a little help here figuring out what I have stumbled across today completely by accident.

I was looking for a frame mount battery box and actually found TWO (with plastic covers) at the wrecking yard that had 6 or 7 Ford vans. The two battery boxes were already removed and sitting in one van, so I thought they had come off two different vans. I wanted the cable harness that was still attached to the frame and had the battery terminals, etc. So far so good.

Got home and had a closer look at the harness and this is what I found: two positive battery terminals (plus a jump post?) and two negative battery terminals that suggest these were set up for TWO frame mount batteries on one vehicle. The longer part of the cable was attached up near the fuse box / Starter battery. Never thought this was a factory option but the parts are ALL Ford.

Has anyone ever seen this? If so, Can someone please give me some guidance on how to get this setup / connected on my E350 V10? I wanted two batteries for house so this may just fit the bill. TIA.

 

[daveb-SMB]

Kinda what I have on my diesel. Not sure about the lengths.

 

[BrianW.]

Yeah, I was gonna say, don't some (all?) diesels use two frame-mounted batteries in place of under the hood battery?

I would guess that "not sure 1&2" are ground-to-frame lugs.

 

[carringb]

Yup, that's a diesel harness. 6.0 vans got both starting batteries on the frame. No big deal though.... just has more stuff you don't need. Just open up the wrapper and pull the extra wires out.

What kind of isolator will you be using? A assume will be using those for a "house" battery bank?

With all the trouble people have with their fancy RV isolators, I'm kind of glad mine just uses the stock Ford AUX battery relay.

 

[1der]

Thanks Guys, kind of what I was figuring when I thought more about it since the connection, under the pretty stripped donor van hood, was to the fuse box bus bar and not another battery (or where I thought the battery would be).

So, if I decide to use both these factory frame mount boxes on my 2003, it looks as if I will have to drill new holes in the frame and I will have to use Group 65 batteries.

Alternatively, I would get a new battery tray fabricated (ala Nuther Battery Box) and then could use any batteries that would fit and be able to utilize the existing holes which are about 27 inches apart. (One set is 15" for the a single box, plus another set of holes about 12 to 13 inches further on) Not to excited about adding to the Swiss cheese feel of the frame.

Open to suggestions / advice on which way to go largest load is 900w Microwave used very sparingly, and Norcold MRTF60 Fridge / Freezer. Some LED lights, laptop, small fan when hot. Two Grp 65 AGM's 20hr@75A could work but it seems it would be much nicer having two 20Hr@100Ah+ batteries (or single 4D).

carringb - Yes these will be for a two battery house bank. I want simple, so it maybe a Ford Aux battery relay, or simply a heavy duty manual battery switch which I can turn off and on to separate the house from starter. Let me know if anyone has a good condition Ford Aux Relay sitting around. I will be installing fuse / breakers for protection.

Already have an inverter and will just add a battery charger into the mix.

Thanks!

 

[dhally]

I recommend putting the most battery in you can afford or have space for! I did quite a lot of measuring and planned to put in 2 - Group 31's on their side. My builder put in Group 27's instead. The Group 31's have about 10 percent more capacity, and are 1/2" shorter, which when turned on its side would give more clearance from the terminals to the body.

One issue about mounting the batteries this way, is that it interfers with mounting a hoop step.

We considered using the factory relay to separate the batteries, but it is only rated 50 amps and I wanted to use a 100 amp separator.

 

[86Scotty]

1der, I would not worry at all about the Swiss cheese look of the frame. These frames are deceivingly strong and thick. You'll see what I mean as soon as you start to drill holes. I strongly recommend a step drill bit and a right angle drill.

 

[Jsweezy]

Hey guys I know this is an old thread but it's related to my question more than any other thread I could find.

This may be a dumb question but how do the aux batteries mounted on the frame rail stay ok with all of the elements under there. I can't imagine having water dirt and anything else getting thrown at it is not an issue but if it isn't then why isn't it?

Thanks!

 

[dhally]

The OEM batteries are standard wet cell, which might need to have the fluid topped off. That would require dropping the battery down to even check it.

But most SMB'ers recommend AGM sealed type batteries for house duty, which do not need maintenance or checking. Plus the AGM can be mounted on their side if desired.

As far as gravel and road grime, I did put a thin sheet of plastic under my batteries to hopefully slow down any sharp rocks etc. If I did a deep water crossing I suppose they could short out?

To answer your question, think about a battery mounted under the hood, and how dirty it can get under a hood. It's not a lot different under the car as far as dirt and water.

 

[Jsweezy]

Ok, ya I guess that makes sense. I just didn't know how it would affect the electronics if water did splash up on the battery or it was submerged in mud or something. I guess if that's the case your already screwed ha ha!

Thanks for the response!

 

[boywonder]

Ok, ya I guess that makes sense. I just didn't know how it would affect the electronics if water did splash up on the battery or it was submerged in mud or something. I guess if that's the case your already screwed ha ha!

Thanks for the response!

Same as under the hood, only dirtier/grimier....

Since they are only 12V they work just fine when wet/muddy, etc. 12V is not enough voltage potential to short out when wet/muddy/dirty.

 

[Jsweezy]

Ok cool, thanks guys!