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Battery Holder From Dilated PVC Hose?

I'm trying to widen about 1 foot of PVC hose. Ie. I want to dilate the interior diameter so 4 AA batteries will fit inside end to end. I'm trying to make a battery holder for my helmet light. The PVC hose is like siphon tube and I want to use it as a battery holder but it's a little too narrow.

I tried heating the hose up with steam and jamming a lubricated metal pipe inside. This worked for a few inches but then there was too much friction. I also tried a smaller metal pipe along with a chopstick but I ended up puncturing the hose.

So the question is:
What is a good way of getting this segment of siphon hose a little bit wider?

Or what else would be a nice waterproof and discreet battery holder for a helmet?

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rkoch35 years ago
Not sure about PVC hose but some solvents will cause some clear tubing to expand as the tube absorbs the solvent... If you use rechargeable batteries and have a way to ensure the +/- stay in contact you can make your own battery packs I assume... never tried it myself. I can tell you, as the solvent evaporates from the tubing it should shrink back to original dimensions. I don't recall what I was doing at the time when I discovered this as it was several years ago, perhaps siphoning gas out of the lawn mower while making repairs to the tank, but the hose diameter had almost doubled in size. The hose I was using was the clear heavy wall type designed for siphoning a fish tank. Be careful when working with solvents, make sure the containers are kept tightly closed, away from spark and used preferably outside in well ventilated area. And always test with a sample... Leave in it the solvent too long and you will wind up with goop.
lemonie5 years ago
Get some wider tubing, like garden-hose.

L
quatch5 years ago
Think of where to place it so that in the event of a crash it won't focus the impact and negate the usefulness of the helmet. Also as I recall, multisport helmets are made for a different kind of collision than bike helmets (many slower collisions), so you should probably get a bike helmet if this is for street driving.

Also, try using AAA, much smaller. Sure you have to replace them more frequently, but with LED's it is still many many house of use.
snotty (author)  quatch5 years ago
All good points.

I have used AAAs but I'm blasting out around 10 watts with my high beams. I use two Cree XM-Ls so bigger batteries are important.
Burf5 years ago
Just pick up a length of 5/8" I.D. tubing at your local hardware store. AA batteries are apx. 9/16" in diameter and should slide in with no trouble. If the batteries are a little too loose, wrap them in a layer of duct tape or masking tape.
The tubing is reasonably cheap.
Kiteman5 years ago
Why not try 3/4 inch water pipe, the kind of stuff used for over-flow fittings. You can get compression fittings (screw-fit instead of glue-fit) to close the ends, and it should be easy to pierce holes in the ends to add connectors for the batteries. You can ensure a good connection by using small springs, just like a real battery holder.
What kind of helmet is it? Could you remove some of the padding to accommodate a single 4 AA battery pack or maybe split it into 2x 2AA battery packs?
snotty (author)  mpilchfamily5 years ago
My helmet is a multisport hardshell kind of like a skateboard or kayak helmet.

I was thinking of using two AA packs but they're a little fragile. I use a 4 AA pack right now but I want something tougher so I don't have to be careful with it.