So my best friend from growing up and I were talking on the phone about my resto-mod 86 F-150 and one of the things he brought up that I should should do outside of OBA is an secondary battery or deep cell under the hood. There is definitely plenty of room for this, and could potentially be wired to a power inverter.
The discussion then becomes:
1) how to properly wire this up into the truck, obviously it will have to be wired in parallel with the main battery.
2) If using a deep cell it may be good to put a cut off switch, but then that may cause charge issues, so running parallel with the mains pre/post starter relay seems the way to go.
3) where is the best place to mount this battery? Is there some preexisting holes for diesel variants? Should I get another OEM battery tray and mount it near the washer reservoir?
I do plan on doing the 3g swap at the same time as this. I may also be rerouting/rewiring the harness so it runs around the engine bay rather than every which way across the top of the engine by making basically plug and play harness extensions, my only concern with this would be built in wire harness resistance values that the computer may be looking for.
The wiring for the aux battery is best shown on these Charge & Power Distribution - Gas Engines pages of the 1985 EVTM. You'll want to see the illustrations on Page 14, and then the main wiring is on Page 15. But the aux battery itself as well as the relay is shown on Page 20.
As you'll see, they used a large yellow wire that is probably already in your truck. It ends below the steering column in the engine compartment. Then you'll need a relay, but the wiring to pull it in is probably already there as well.
But the aux battery tray won't be there. It is shown on this page in Documentation/Fasteners & Illustrations/Front Clip/Fenders & Aprons. And that's on the driver's side.
But the later battery holders are much stronger, as Jim points out. I'm going with at least one of those on Big Blue's transformation. But, since I will have an air cleaner box and power distribution box to fill the left fender, I may have to move the aux battery to the right side. Hopefully two of the latter battery trays can be used for that.
The bricknose battery holders mount ABOVE the inner fender and the battery clamping wedge is either glass filled plastic (nylon?) or steel.
I have seen both, but never rubber, even hard rubber like an old comb.
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with an Edelbrock 1826 and Performer intake.
Too much other stuff to mention.
Battery Carrier or Tray: E7TZ 10732-A r/b F4TZ 10732-B
Clamp: E7TZ 10718-B (Perhaps not "rubber")
Brace (Battery Tray) E7TZ 10N697-A
And here's a better snag of the illustration to include the brace part #:
And here's a shot of Big Blue's current battery tray on the left, and the to-be battery tray on the right. Note that the Bricknose tray will use the same bottom two bolts as the Bullnose, and will just take another hole in the fender for the brace However, it is close to the relay so that probably ought to move.
The support arm is riveted to the later tray, so it's easy to move the support to the other side. There are 2 styles: flattened tube, and flat strap:
But it's not nearly as easy to separate the lower bracket that's spot-welded to the bottom of the tray. I think you might have to reverse all its bends to make it LH; or just copy it in reverse, and fabricate your own.
Either way; the base clamp is superior to the bullnose J-hook clamp. Especially if you get the long clamp bolt.