Do 18650s rattle in 21700 lights?

You can buy the M21B with an included battery from the AliExpress Convoy store, apparently they ship to Canada. If the specific model id not available contact Simon or ask in the main Convoy thread. The batteries you mentioned have ~5A CDR so their runtime may be a bit lower than expected in the M21B.

First off, not all 21700 lights will take 18650 cells, even with an adapter tube, or shimming to reduce lateral movement.

The Sofirn SP35 has only a single spring in the tail cap, and an 18650 (unprotected flat top 30Q, in my case) is too short to engage both it and the contact pad in the head.

My Sofirn Astrolux EC01 has dual springs, and was bundled with an adapter tube. But there is still slack inside the adapter, and between the adapter and the body, so shake it hard enough and it will rattle. Enough force can still overcome the steadying tension the spring(s) provide and allow the cell to shift.

My local hardware stores often have rubber O-rings in the isle that they have toilet component parts (like where the tank valves are).

if you have ace hardware in your area they have drawers of stuff like o rings.
you can test fit on the spot.
and o rings are easy to stash in your battery boxes(you are using them right?)
if you need quick and easy a strip of cereal box wrapped around the cell will do.

I wouldn’t bother going to a store to buy something so simple, a folded piece of cardboard will do exactly what any rubber oring will and work just as well. I bet wherever you are right now Bort, within reach is something that can solve your issue. A bit of card or rubber band will work just fine until you get your 21700 cells. If I was in the US Id scoff a Charleston-Chew fold up the wrapper and stuff that in. I can only get Charleston chews at fancy import candy stores which sucks btw.

Next problem.
Why are ants going in my flahlight and charger?

Snakebite, two possible answers: Ants are looking for a warm dry place to build their nest; or they are looking for something edible.

I also have ants frolicing in my kitchen. Some of them like to go into my cupboard where I keep my coffee mugs. I guess they smell residue of milk and sugar in mugs.

I have not owned any 21700 lights so i asked if there would be a problem using an 18650 battery in it.
Not like i asked the meaning of life :person_facepalming:

That was a joke about using candy wrappers for a spacer

FWIW even a few ants stuffed in there will work well too.

I prefer a little more aseptic and less blood and guts :confounded:

IIRC ants make some antiseptic fluid and lack blood.

They are not solid and without bodily fluids :confounded:
A spacer/washer is a much better solution

take a piece of stiffer paper like a glossy junk mailing .. not even needing to encircle the battery , sometimes just strips on one side of the cell will work . or plastic strips cut from a container or lid will work . Once the material takes the shape of the tube it will naturally just stay in place . Simple as pie . Problem solved .. Now onto that Ant problem ,

try diatomaceous earth and a little sugar to it to bait them into eating it

Strips of cereal box have always worked well for me.

Nope…no way, let’s make it a lot more complicated please.

I haven't tried this, but I like this solution the best (so far.)

I think some people might not like paper because they see it as flammable while plastic seems less so . if there's fire in your battery tube ..a chemical lithium ion fire ..that's the least of your problems ..

Paper ? or plastic ?

I prefer something slick so there's little resistance on the battery when you're changing batteries .

maybe wrap your cells in crisp new hundred dollar bills :)

If i had crisp new hundred dollar bills i would be buying more flashlights :innocent:

Both of my 21700 lights work fine with 18650s, (FW21 Pro and FW21 X9L). They did come with adapters though.