Today's Fabrication Project: Battery Hold Down

[Don Plumley]

I picked up a lightweight Odyssey battery. Needs a hold down. Rennline has a very nice one, but for $135, I thought I'd take advantage of a little spare time and make one on my own. For reference, here's the Rennline unit:



I made a template for the base, cut out some 3/16" aluminum, did the grinding/sanding dance, here are the parts ready for assembly (this is kind of like watching a cooking show where all the ingredients are prepped -- getting to this part probably took about 4-5 hours):



And the assembled mount. The 5/16" threaded rod connectors are held to the base by countersunk machine screws. This and the rod are secured with some locktite:


Here's the base of the mount in the trunk. I used the existing hole and mounting ledge, and also ran the base under the ABS mounting bracket for additional security. It's really held in tight. In the back you can see some automotive foam/weatherstripping to keep the battery from banging into the trunk wall:


And the completed unit in place:



I ran the top clamp over the right edge in case I decide to mount a battery cut-off switch later - like the Rennline unit. But as I read the POC GCR, the switch needs to be behind the struts, so I may end up cutting it down. Although I provided extra clearance around the terminals, I think I need to make it even bigger around the + terminal, and may consider coating the entire surface in some sort of non-conducting material. But it was the sort of quick fun project I needed to re-develop a sense of accomplishment.

Cost? Scrap Aluminum, $8. Hardware, $7.09. Time - well, let's just say I did it for the fun of it. Weight savings - about 10 pounds from an Optima. Now, back to the suspension work...gotta get the bushings around the TRG front sway bar. And the dollar savings are needed as I just ordered a full set of ERP suspension arms for the rear (ouch!).

Any comments or suggestions on how to improve or make safer is appreciated.

[mmastro]

Nice work, Don!

[Dan in Pasadena]

Don, Very nice workmanship. A few questions?

- Why all the holes...just for weight reduction/Rennline appearence?

- Am I missing something or is the battery in the Rennline shot oriented with the terminals near the body and yours is oriented with them away from the body (which seems safer

Yeah, I'm with you that the more distance you keep between that positive terminal and anything aluminum is better. I'd wrap the edge with either some small diameter rubber tubing or possibly mask and apply that rubber stuff you are supposed to dip tool handles in. It comes in some colors. You'd have to strip the mask before it dried however. Really good work.

[Don Plumley]

Dan-
Holes: Weight Reduction. Did you see my gas pedal?!
Rennline photo: the photo is not in a 993, I'm guessing it is a Carrera and you need that orientation for the battery cables.
I thought about the brush on/dip plastic stuff, could even wrap it in an inner tube. Or just a bunch of electrical tape. I think the POC GCR wants a coated bracket, but I'm not sure mine would pass their specs anyway. Shame to cover up the shiny aluminum though.

Thanks!!

[Dan in Pasadena]

Don, Use the dip stuff but just on the edge. Since your car is silver (I don't think they make that stuff in silver, but maybe blue?). How about masking and just coating the last 1/2" or so. Nice and thick and wait till it JUST gels a bit before carefully stripping the mask. It ought to look great. If it doesn't? Yank it off. I'm with you, don't cover up that nice aluminum.

EDIT: You know what else might work and look finished? DOor edge guard. The pinch type stuff in black. Orient the ends where you can't see them. Cheap, fast, easy.

P.S. Show me your gas pedal and tell me the story!

[Kroggers]

Nice work - this is on my project list

[Don Plumley]

Dan - here's the gas pedal project and the floor board project.

Your idea about door edge moulding has real merit. The piece is much thicker than a door, but with some heat (famous last words) it could work. I have some scrap clear pieces I could try. Or simply use a vinyl hose that's split.

If I were more adventurous, I'd cut the cable and put on big terminals instead of the threaded posts. Maybe I'll gander to the auto parts store today and see what they have...

Thanks!

[Don Plumley]

Dan - here's the gas pedal project and the floor board project.

Your idea about door edge guard has real merit. The piece is much thicker than a door, but with some heat (famous last words) it could work. I have some scrap clear pieces I could try. Or simply use a vinyl hose that's split. It does need to go all around the mount so the surfact the contacts the battery top is level though.

If I were more adventurous, I'd cut the cable and put on big terminals instead of the threaded posts. Maybe I'll gander to the auto parts store today and see what they have...

Thanks!

[Por_sha911]

Originally posted by Don Plumley
Cost? Scrap Aluminum, $8. Hardware, $7.09. Time - well, let's just say I did it for the fun of it.
Any comments or suggestions on how to improve or make safer is appreciated.

Wow! That is beautiful. How much fun did you have? Would you like to have that much fun again? If you did, I could use one of those!

[RLJ]

Nice craftsmanship. Step up and spend the "big" money and get it powder coated Maybe $10.00.

Randy Jones
1971 911 "Iris"

[Bill Verburg]

As w/ the floor boards, nice job!

[Don Plumley]

Thanks to the helpful comments here, I improved the mount by 1) using a small piece of angle bracket on the bottom mount to absolutely prevent the battery from sliding L/R; 2) increased the size of the terminal reliefs; and 3) glued a piece of vinyl hose along the perimeter of the mount to provide insulation and additional grip. Here it is:

[randywebb]

I bet I could use the top and the threaded rod to hold an Optima in side my L. side battery box...

[DUK]

Looks great Don. Gives me an idea for my battery I'm moving to the smugglers box. Thanx

[DW SD]

Great work, Don!
For more ideas, here's a different style with the battery in the smuggler's box. Workmanship not as nice as Don's!

The battery is held by a lip that goes all the way around it and then the clamp from the top, if the car were on its back.

This one is made from stainless, probably 18 to 20 gauge (like the front of a refrigerator door. I bent it in the vice, using a 1"x1" square tube like a pressbrake.

Doug

[RickM]

Don, Nice work as usual. The plastic type material is called Plasti-Dip. You can dip, brush, thin and spray or now available in aeresol (sound like a commercial? ). A good hardware store will carry.

http://www.plastidip.com/

[jtfreels]

Good job! What did you use to cut the large holes. Now I've got hole saws for wood, surely that wont work?

[RickM]

Originally posted by jtfreels
Good job! What did you use to cut the large holes. Now I've got hole saws for wood, surely that wont work?

If you take it slow and dont mind throwing them out afterwards they will work. The proper hole saw for the job is Bi-metal saw. Can get them at any good hardware store.

[Kroggers]

Originally posted by DW SD
Great work, Don!
For more ideas, here's a different style with the battery in the smuggler's box. Workmanship not as nice as Don's!

This is probably a stupid question from a novice, but what is the benefit from putting the battery in the smuggler's box? I am going to get a new battery next week, and looking at options etc - is relocating the battery to the smugglers box a good suggestion, and why?

[DW SD]

Originally posted by Kroggers
This is probably a stupid question from a novice, but what is the benefit from putting the battery in the smuggler's box? I am going to get a new battery next week, and looking at options etc - is relocating the battery to the smugglers box a good suggestion, and why?

Not necessarily in any particular order:
1. It is a clean install (aesthetic).
2. allows removal of battery box - can route brake cooling ducting.
3. reduces polar moment of inertia.