Drilling battery terminals?

This may be a bad idea, but let's discuss it anyway.

I recently scored an Odyssey PC680 battery for $20. The plan is to put it in my ESP Z28. The only problem is that the battery terminals have 6mm x 1.0 threads, and the car has 3/8x16 side post terminals.

The only adapters I've found cost as much as the battery did. So in the name of saving money GRM style, I'm wondering if it would be safe to drill out the battery terminals and tap them to fit the GM terminal bolts.

If not, I also have some scrap 1/8 aluminum sheet. Does aluminum conduct electricity well enough for me to make an adapter? Would a sheet steel adapter work any better?

why not use the 6mm bolts and maybe a washer. Are the GM bolts part of the cable and can't be removed. ? In drilling, be very careful that you don't go too deep. Tap drill size is 5/16 or .3125 or 7.97mm

iceracer wrote: Are the GM bolts part of the cable and can't be removed. ?

Yes, or at least I can't figure out how to get them out.

You just have to be sure you have at least an 1/8" diameter margin to drill out........

Only thing I would do would be to do this on a drill press to ensure you have a straight hole to tap.....

what iceracer said, use the 6mm bolt in place of the 3/8. You should be able to remove the 3/8 w/ a punch. Find a washer to fit the 6mm ID and the recess of the terminal OD.

The 3/8 battery threads aren't very deep at all, 3/8 to 1/2 at most, a bottom tap might work but I'd be weary of kluging it.

try doing a test drilling and tapping on an old battery, it's pretty soft material.. that's why I was leery. 5/16 drill for 3/8 tap. Bottom tap might work best on short tap depth

Battery terminals should be (always have been in my experience, outside of motorcycle batteries) made of lead. You could drill and tap it all you wanted. It won't hold E36 M3. You would be better off making an adapter. Just be sure to use a lot of aluminum. Look at the cross section of your battery cable. You want that much cross section in your adapter. Or cut off the ends on your cables and put new ends on that fit your battery.

http://www.summitracing.com/parts/ODY-3217-0006/

Don't drill all the way through.

I worked as a groundskeeper at a plastics factory in college. "My" lawn tractor's battery terminal broke, so the maintenance dude tapped it for a bolt. Unfortunately, he drilled all the way through into the insides. Terminal later came loose, I wiggled it, and the spark ignited the hydrogen inside, blowing me across the room--and getting battery acid everywhere (my eyes, mouth, etc.)--and I couldn't hear for a few hours. No lasting effects, but could have been mucho worse.

that said, an Odyssey is an AGM, so it doesn't have a lot/any hydrogen gas hanging around inside. Don't quote me on that, don't do anything stupid, don't sue me.

Oh, and he's trying to save a bunch of money, so he doesn't want to spend that on the terminals. I may have an extra pair of those blocks from the Brailles I'm using on the LeGrand--I just bolt directly to the battery (lighter) and don't use the brass lugs. Let me check around.

If you make an adaptor hammer out some copper and star washers.

Per Schroeder wrote: Oh, and he's trying to save a bunch of money, so he doesn't want to spend that on the terminals.

safety first, safety first

cheap isn't always the right answer

fasted58 wrote:

Per Schroeder wrote: Oh, and he's trying to save a bunch of money, so he doesn't want to spend that on the terminals.

safety first, safety first cheap isn't always the right answer

Sploding batteries are very bad JuJu . Tread lightly. Use PSE.

I would cut off the bolts from the terminals and use the correct ones for the battery before I drilled and tapped the odyessy's terminals

why not scrap the stock cable end in favor of a ring terminal and then the propper bolt?

The ends on GM side post battery cables just press out. Easiest if you drive your car to warm the cables up first, but then they just press out with your thumb.

Alternatively, wedge a flathead screwdriver in there and pry them out. They just pop in and out.

fasted58 wrote:

Per Schroeder wrote: Oh, and he's trying to save a bunch of money, so he doesn't want to spend that on the terminals.

safety first, safety first cheap isn't always the right answer

That's why I posted my story....

93gsxturbo wrote: The ends on GM side post battery cables just press out. Easiest if you drive your car to warm the cables up first, but then they just press out with your thumb. Alternatively, wedge a flathead screwdriver in there and pry them out. They just pop in and out.

Thanks. Got them out, and the 6mm bolts put in. The battery even starts the car, too.

Thanks for the offer of the hardware, Per, but I guess I won't need it. I appreciate everyone's input on this one.

Will wrote:

iceracer wrote: Are the GM bolts part of the cable and can't be removed. ?

Yes, or at least I can't figure out how to get them out.

They come out, they're just a bit of a pain. Set the battery end of the cable on a slightly opened vise and tap it out with a hammer. They are pressed past the threads onto the shoulder of the bolt so they don't fall out, so you just have to "convince" them.