Now that there are so many “standard” battery sizes, it makes some sense to think more about adapter tubes. Most of us have use 18650 to 26650 tubes, and some really nice ones exist for this sole purpose. But now that is just not enough!
So, I am starting to look for proper diameter over the counter stuff to make the following tubes and I am hoping we can put together a list of what we can use. It would be great if the stuff could be picked up in local box stores or hardware stores.
These are the sizes that I could see being useful:
18650 to 21700
18650 to 20700
2AA to 3 18350 (Solarforce L2 with 1x 18360 extension tube)
Others might be needed, feel free to add to the list.
If you know of something that works or can be made to work by removing external diameter, post it up!
the problem is, the light makers do not try to be standard, mostly
they might change threads or pitch at any time
the only goal is to make a light to sell, and usually no one cares to swap pieces around
you can find a few making that effort, but that will be the $100 lights, not the $10 ones
and if they do, they are already selling their own adapter tubes
just saying
this will be a hard business to get into
Yeah, the 18650 to 26650 is easy. Even a rolled up piece of paper will do.
It’s the 18650 to 21700 that is tougher, or any adapter needed for a different length. You’ve got to extend it with some metal on the end, not just a plastic sleeve.
Most cases, as long as the length is compatible, you can just drop in a smaller-diameter cell as-is, no rings or spacers or anything, and the internal springs will hold it in place without rattling around. I’ve even used an 18650 in a 26650 light without issue.
Still, anyone who’s anal-retentive enough to “need” the “proper” spacers can do it as above, a sheet of paper folded over and wrapped around the cell would be enough, else a thick rubber-band (like those fat ones that go around broccoli stalks) would keep the cell centered and cushioned nicely.
Another quick example. Mum’s craplight that takes 3×AAA, not the usual shorty holder but one that can also replace an 18650 cell, ie, with the longer pogostick terminal on the positive end. Only got the shorty holders after alkaleaks ruined the come-with holder. So? Ball up some Al foil, smoosh it into a cylinder on a tabletop, drop it in to test height and diameter, wrap with a strip of torn-off paper napkin, stick it in there, good to go.
Even before, I’d do the Al foil thing, and put a dimple on one end where the pogostick contact on the tailcap would fit into, to more or less keep it centered. Always worked, never shorted except when screwing on the tailcap. Once it’s in-place, it’s good ’til the hateful little alkaleaks croke and need to be swapped out.
While I hate to come off as a safety weinie, this is risky business since the spring on the positive side can short out the cell in one of two ways. The risk increases with longer springs and cells with weak wrappers/insulation. I would highly recommend using some sort of centering device. Many diy/hack options exist - some mentioned here - if you don’t have access to purpose built accessories.
The Astrolux MF01-Mini includes 2 adapter tubes - one that makes the 18650-to-21700, then another 21700-to-26650. Using both for 18650-to-26650.
But in this case the MF01-Mini is built (spring) to accommodate the length of the 18650 and the longer 21700.
In the case of Fireflies flashlights (PL47 / E07) or the Astrolux FT02, they include a battery tube adapter that adds a bit of length for 18650 to become 21700.
The 18650-to-21700 battery tube adapter for FT02 is also sold stand-alone in Banggood, as per my last checking.
Oh I have plenty of tube adapters. Usually not one handy when I need one the most. Hence the tape. Wrap around cell, close to top and bottom, keep wrapping, diameter increases, it takes up the space, etc.
I try to find things like o-rings and such. It is not anal retention… I had a flat top 18650 in one of my favorite 26650 lights, fit tight and seemed to work well but it shifted and scuffed up the wrapper and dead shorted on the positive end… Talk about exciting!
I have several proper 18650 to 26650 tubes now, but the one I need the most is 18mm to AA for something I am working on.
Where it does get anal… I hate anything that rattles. Flashlight, shotguns, cars… should not rattle!
That might be the going rate for a quality adapter…
This guy started a thread a while back:
They look like nice adapters, and he has made some in many different sizes.
If you owned a 3D printer, you could easily make your own for less (per piece) but if you think about the investment made (time and :money_mouth_face: by the guy doing this, it is probably worth the $8.
Physical side-clicky like on a Mag? Napkin wrapped around the 18650 and a big wad of Al foil down the pipe…
If a 32650 would fit (I had one I thought would fit, but it was too snug, and I didn’t want to damage the wrap), all the better, but a 26650 would do better in a pinch.
When I was setting up my 2xAA Surefire C3 M31W combo I ended up finding some tubing at the hardware store that worked. It took some searching and I believe it may be for underground sprinkler systems, see below for album link. It fits AA cells very well, but the OD required “some” sanding to fit my Solarforce hosts (L2x models with various tubes to fit 1, 2 or 3 cr123/18650/etc). It required a lot of sanding to fit my C3 body tube, which was easily done mounting the plastic to my drill.
I do that most of the time. Unless it rattles too much and drives me crazy. Then I just wrap some tape around the cell.