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This is a thread on a simple trunk mount battery box. One of the problems with mounting a battery in the trunk is that a simple tray that you can buy at most auto parts stores will not pass tech at most racetracks because the battery needs to be in some kind of a box. A simple marine type battery box will not pass either because it is plastic. My solution is a simple steel bracket that combines with the marine box to give you a simple, cheap safe method of mounting your battery in the trunk or a remote location. This assembly has passed tech as NHRA strips, as well as circle track, mudd bog, hill climb and countless other types of motorsports over the years.


You will need a few tools to build this:

-Some way to cut metal- a hacksaw will do, but a chopsaw is better.
-Drill or drill press.
-Welder, a 110 volt welder will do fine.

Here is a materials list:
-30" of 1" x 1" x 1/8" angle iron.
-30" of 3/4" x 1/8" flat steel.
-6" of 1/2" square tubing.
-8-3/8"-16 grade 5 bolts.
-4-3/8-16 nylon lock nuts.
-2-3/8"-16 high nuts.
-Four 3/8" large diameter fender washers.
-1-Plastic marine type battery box.

-I bought the steel out of the scrap bin at of my local metal supplier for $7.50.
-The bolts and nuts were $2.00 at a hardware store.
-The battery box was $8.00 at Wal-mart.

Two pieces of angle iron are cut to 14" in length. I cut them at a 45 degree angle because it looks better. A 3/8" hole is drilled at the end of each piece of angle iron to bolt the bracket down to the trunk floor. The angle pieces are squared up to each other, and a cross piece of 3/4" flat steel is cut to the outside width of the plastic battery box, and everything is welded up:



Two pieces of 3/4" flat steel are cut to 6" in length, and a 1" long 3/8-16 bolt is welded to the end of each piece of flat steel. The uprights are then centered on the base of the bracket and welded 90 degrees to the bottom of the bracket on each side:



Two small pieces of 1 1/4" long 3/4" flat steel are cut and a hole is drilled 1/2" from the end of each piece. These two pieces are welded to a piece of 1/2" square tubing which will serve as the cross bar:



The high nuts are then threaded onto each of the "studs" on the uprights. The high nuts have 1" of thread that will provide adjustability for any battery. Two 1" long 3/8" bolts bolt the cross bar to the high nuts. The crossbar can also be flipped over to provide another 1/2" of adjustability either way:



The box and the lid are both notched for the cross bar to clear, I use a pair of tin snips:





The battery box is placed on the bracket, the battery is set in the box, and the cross bar is bolted down:



The lid is set on top and the assembly is complete. The lid is held down with the nylon strap that comes with the box. Four holes are drilled in the trunk floor and the bracket is bolted in place using the remaining 3/8" bolts with the fender washers and locknuts on the bottom:




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Very cool write-up. However, I thought boxes like those weren't acceptable according to NHRA rules. Here's the clip from their FAQ.

Also, the battery must be completely sealed from the driver and/or driver compartment. This means a metal bulkhead must separate the trunk from the driver compartment, or the battery must be located in a sealed, metal box constructed of minimum .024 inch steel or .032 inch aluminum, or in an NHRA accepted plastic box. In cars with a conventional trunk, metal can simply be installed behind the rear seat and under the package tray to effectively seal the battery off from the driver. In a hatchback type vehicle the battery box is usually the easiest solution, since the alternative is to fabricate a bulkhead which seals to the hatch when closed. At present, Moroso is the only company which offers an NHRA accepted plastic battery box, part number 74050
 

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Very cool write-up. However, I thought boxes like those weren't acceptable according to NHRA rules. Here's the clip from their FAQ.
Our local tech wants metal, sealed and hose vented to outside, to pass my son's hatchback. He used a surplus night-vision goggle case that's probably a standard ammo can size. Strong, simple, and cheap, bolted to the floor with grommets and silicone around the cables.
I'm sure F15Falcon's setup would pass in other situations.
 

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While what you did is nice, it doesn't comply with NHRA rules. It may pass tech somewhere, but it's still not right. That box will do nothing to contain liquid. Good job though.
 

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Discussion Starter #7 (Edited)
I know it is not what the rules say, but it has passed NHRA tech at several tracks that I have installed these on. The plastic Poly box by itself will not pass as NHRA is more concerned with the box ripping free and becoming a 40 pound missle, but a welded steel 1/8" thick bracket solves that. Alot of the metal boxes that are sold rip free under a hard impact because they are made from thin gauge aluminum or steel. With an Optima type battery, this bracket will pass even without the box.
 

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The reason that has passed tech in the past is because they want your money and are willing to look the other way. Trust me I know as I was a tech official for several years and was told to let all sorts of infractions slide by. I would say if cars were held to the rule book, 30-50% would not pass tech. Now thats a lot of income for the track to lose. It's about the money not your safety. The track can enforce (or not) any rules they want, they are not accountable to the NHRA.

I'll give you an example. We were told that if the battery was a dry cell and was in the trunk it did not have to be held down at all, WTF? Crazy but true because they want your money.

Yes, they don't want a 40# weight flying around but the other thing is that they don't want the acid leaking out of the box, that's why a dry cell sealed battery (like a Optima) is not required to be in any type of box, just held down.
 

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F15: What did you use for battery cable, and how much did it cost?

Reading wilit's FAQ info, it sounds like they are concerned with fumes and possible explosion of the battery. I bought one of the cheap Summit kits to relocate the battery in my Ranger to the bed. It has two long bolts and a metal top hold-down. It seems like it was cheaper when I bought it, but considering it comes with 23ft of 2ga cable, I thought it was a good deal.

Summit SUM-G1200A - Summit® Battery Relocation Kits

I doubt the kit meets NHRA rules for a trunk-mounted battery, but I have a feeling the rules are a little different when the battery is in a pickup bed? All I know is, the tech guy didn't look twice at it, but they did bug me about my throttle return springs and rubber fuel line, so they were paying attention.

 
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