I’d been looking around for a battery adapter sleeve to convert a 21700 battery tube to hold an 18650 battery without rattling. I have seen some people use plastic o-rings or thin piping, but I wanted to buy something well made. I saw on the Fireflies website a really nice one for just $1.50, with a removable brass button (in case of going from flat top to button top). But an order I placed with them has gone nowhere. No response from customer service for 2 weeks. It’s a real pisser, because I’ve enjoyed this brand. Anyway, I looked around but couldn’t find something equivalent for a decent price.
Anyone here have suggestions on what to get, or a nice DIY approach?
I use some O rings I got from the hardware store. 2 per 18650.
Best part is the rubber doesn’t rattle like some of the plastic sleeves.
All the Best,
Jeff
Could message Sofirn and ask if they’d sell you some of the ribbed tubes they include with lights. I don’t really use them myself but in toying around with them they fit their lights and all but one of my others pretty well and the 18650s all fit great except a particularly fat Keeppower protected cell. I’m sure those are available on aliexpress for cheap but watch out because a great many of them that look the same are actually 26650 adapters.
I saw this awhile back when helping a friend find a lens for his Eagtac….not sure if it’d work with all tubes or what the dimensions actually are but to me it looks a bit fat. It’s a can, kind of the reverse of those shorties you saw on the Fireflies site.
@Jeff51 - Trying to avoid rubber o-rings as they tend to grab a bit too much to the tube sides. Something like a flexible plastic that will slide easily but take up the diameter slack. Maybe a plumbing supply plastic washer could do the trick. Will have to take a flashlight with me to Lowes or Home Depot and fish around.
@LightBringer - Paper towel could certainly work in a pinch, but hoping for something a little more robust. But actually you give me an idea—those packing foam sheets cut to size might do the trick.
@Correllux - Those EagTac tubes look great, but at the price of a 21700 cell, not really worth it IMHO. If it was $12 for 2, would consider that. I’m hoping FireFlies wakes up after the Chinese National Holiday and let’s me know about availability of their solution.
Yes…a bit too pricey. Those Fireflies ones can be found all over ali, ebay, and even amazon but the prices are all over the board. Pretty standard adapter and they come in a few colors…
If you have any cylindrical tube holders that various drill bits and tooling bits come in and are around 3/4” ID, they’re often about the right thickness and a slit along the length would make sure they’re snug on the cell. Those handi-pak tubes of solder might also work but I think they may be a bit thin.
I’ve used left over toilet paper rolls and cut them to the desired length, then to the width needed by cutting them up the middle, rolling them around, and wrapping them with tape. Probably not describing it too well haha.
This issue has been the bane of some of my lights – the rattling of the cell.
Unfortunately, I never found the ideal commercially available plastic tube to make adapters. So scrounging about my place I found some ‘fish paper’ that with a few wraps does the job. Less than the ideal replaceable sleeve, but they work. Other stiffer cardboard ‘wrinkles’ with tight bends; but I suppose I could wet them and then let them dry to form.
I have always had flashlights with 18650 battery, when I bought the PD36R and then the PD36 TAC which use 21700 battery I also wanted to buy the adapter Fenix ALF-18 Battery Holder.
I tried it once it works fine, with it I can use my 18650 even if flat (it has a spring inside under the positive pole)
It remains as an emergency use, it was bought for that.
The Fireflies ones have appeared elsewhere but with a cost about 4x that of Fireflies. Another one I’ve seen at Banggood has the half-tube on the other side, the bottom. $9. Looks fairly well made and eliminates the button/no-button top issue. I know what you mean, about those drill bit holders. Will have to check that out. Heck, if buying a drill bit WITH the tube that works is cheaper than $9, worth it to go that route.
That certainly works, though not elegant. Considering cardboard, yeah—cereal boxes can be very good. Especially if you order one of those jumbo boxes that uses slightly thicker material. I buy Nature’s Path cereal all the time and save the cardboard for packing material when shipping things in bubblewrap mailers. I was thinking… of just taking that, rolling into a tube, and secure with some tape having adhesive that won’t ooze out.
The Fenix ALF-18 looks decent. Battery Junction has them for $5.99… but I think shipping minimum with them is usually $8.
Just wrap some insulating tape around the top and bottom of the battery, works fine, done it myself.
To use it in another light if needs be remove it, though I tend to keep 1 battery to 1 light normally so never need to remove it.
Have you asked around for someone that has a 3D printer? Might be a buck or two but they are out there and can be shipped to you. If you know someone that has one they could make a ton for 10 bucks. Just remember that because they can make it doesn’t mean they will do it for you for free.
Ask around, you might be surprised by local makers.
Yeah, this may be a sensible way to go. You don’t even need to fully wrap the whole cell. Just 75% of it. And with the heat generated, it should warp the plastic to conform… Will give it a try. Thanks!
Here I use a sheet of ‘fish paper’ to reduce the body tube inner diameter: MantaRay 21.86 ID, Molicell 20.53 OD (20700 format)
The material can be found here
Comes precut at 65mm and is quite economic at $1.00 for 10 feet (but they get you on the shipping). Should be some without the sticky backside in Ali.
Mine is .40mm (.016”) thick and has a natural roll. It stays within the flashlight body.
For converting the 21 to 18mm, using 2 or 3 concurrent rolls (.4mm x 3 = 1.2mm per side; close enough to 1.5 but tight fit – 2 rolls has just the right play).
Plastic jugs and the like are usually made from polypropylene. Rather stiff and too high a melting point (135 to 175 ºC) to mold with the battery therms. Also, most probably thinner. Hence more ‘rolls’.
