Something i have been wondering, since i don’t currently have any 21700s if i buy some lights that use them and put my 18650s in them for now will they rattle/flicker?
Theoretically a 18650 battery is 3mm thinner and 5mm shorter than a 21700 battery. They certainly will rattle, and most likely won’t work without some type of spacers.
All of my 21700 lights work with 18650 flat tops. I use o-rings or a factory tube to center the cell. If you lights do not have springs on both ends, it is likely you will have issues with the shorter flat top cells.
I am considering the Convoy M21B and i have UR18650FM 18650s and some Samsung ICR18650-28As.
I have no idea if it comes with centering washers, though its not mentioned so i am leaning towards no.
Use factory tube and put a rubber band around it so it doesn’t slap up and down, or some electrical tape. Or even better just run a 21700, cells are cheap & the 21700 hold moer powa’s.
I think you’ll find most lights that are 18650 and 21700 compatible may have a little bit of rattle to them when running 18650 cells, but they should be tested to ensure no breakage of circuit continuity. Besides, very easy to slip over a few O-rings on the 18650 to help with the centering.
Should be able to find some at your local hardware store or building center. 18mm inside diameter/ 21mm outside diameter. Walmart.com has listings for 10 packs for $5.49US. Not sure what access you have to that up in Canada (you are in Canada, right?). Amazon.CA probably has something close.
I use a pair of O-Rings from a hardware store. I just looked a the packages and picked ones I thought would work. No rattles. And I like having sir space around the cell. As opposed to wrapping it in cardboard or something like that.
Length wise all seems to be an OK fit. Most of my 21700s are a tight fit length wise.
Seems like I used a magnet spacer in at least one of my lights - but I can’t remember which one(s).
All the Best,
Jeff
I don’t know how remote you are out there in Oh Canada, but if you’ve got a hardware store chain in reasonable distance, give ’em a call and see. Or, just pop over on eBay. You can get all kinds of cheap o-rings from China on the cheap.
I’ll check it out next time i get to the hardware store, don’t go there much becasue of covid but when i get there i shall look carefully. Probably ask a helpful associate.