Wrench Scramble 2015: Witty Title about a Battery Box

battery relocation box
For those of us with good-but-not-great fabrication skills, 1/8″ X 1.5″ Ell channel steel is wonderful stuff. Thick enough to weld without blowing out, thin enough to weld with even the most mediocre of welders. With a halfway decent intuition of solid mechanics, you can sturdy built boxes, frames, etc. Case-in-point: LeMons grade battery box and hold-down. Follow along for a simple kinda-tutorial for keeping these joules in place…

A little context: the battery mount in the engine bay was mostly rotted out. Secondarily, we’re trying to move weight rearward for obvious reasons. I’ve got a BMW battery cable (they were factory trunk mounted) that just so happens to reach to under-floor cavity right behind the cab. We’ll put the battery on the passenger side to offset the driver’s weight.

optima battery in trunkdewalt chop saw

For straightforward cuts like this job, I use my woodworking chop saw with a 12″ cutoff blade on it. Were this something other than LeMons, I might entertain doing 45 degree angle cuts, but it’s not really worth it here.

We need to clamp the battery down and prevent it from sliding side-to-side. Turning the Ell inward on two sides gives the battery something to rest on, which is good given the quality of sheet metal beneath it. In my case, this was three sections at 10.5″ and two at 9.5″ inches.

battery relocation box

Mock everything up with a little extra room (~1/4 to 1/2″ in each linear dimension) in case the next battery isn’t exactly the same, then lay down a few tack welds and test fit. With the supervisor’s approval, it’s time to burn them all in. I didn’t weld every possible edge, as that would’ve been massive overkill.

tack weldswelds

I’ll use some threaded rod to hold that top bar on, so a pair of nuts is getting welded to the base. To make sure the rod goes all the way in, I opened up some holes. Basic metal-working wrenching tip: start with a tiny drill bit and work your way up in size. Also, grab a good quality step bit, as it speeds things up massively. Lastly, drilled another hole and mounted up the grounding strap to the frame.
welded on nut
Back into the car, I mocked up the holder’s future home, knocked down the worst of the corrosion and spray-bombed the area…only to immediately re-grind a few sections where I can weld the mount to the body. On one end, it’s grabbing the sturdiest section of floor around and it’s joining the rocker panel on the other. Probably a good 8-10″ of weld length. It’s more likely to take the whole floor with it in a crash than anything.

All welded in, cables attached. Need to cut the threaded rod to length and re-rattle-can the exposed areas.
diy battery trunk mount
 
 

6 Comments

  1. I’ve heard the phrase “Junior Arc Welder”, usually in conjunction with shorting battery terminals together, but that’s the first real Junior Arc Welder I’ve seen.

  2. How are the battery cables getting to the engine? Zip tied to the cage, and through a hole in the firewall?

    1. There’s a hole in the firewall, and a few naturally evolved speed holes elsewhere, and I don’t think we’ve bothered zip tying it down yet. There’s a bunch of other wiring to do first. (And it’s not like it moves under its own power yet… No drive shaft. But the ranchero is finally together enough to measure the DS, so, SOON.)

      1. I have a similar battery mount in essentially the same relative position in my racing 96 and have found that I get plenty of current for the starter simply by grounding the negative cable very close to the battery. On the other hand, my former MGB had a setup much like that from the factory; I eventually gave up trying to maintain an adequate ground connection and just ran a negative cable all the way from the battery to the starter itself.

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