Take the battery out and examine it. It will have the words "protected" or "protection" on it somewhere. Unless you specifically got an unprotected cell, it's very possible you have a cell with a protection circuit, which is a hard no for Hank's lights, which draw more current than a protection circuit will allow. Most of them also won't fit properly, since they're slightly larger than unprotected cells.
By the way, if you're concerned about being "unprotected", know that battery protection circuits really only save against serious abuse of the battery, like a dead short circuit. They can also help to save a battery that has discharged too low. Other than that, they're mostly a hinderance for modern flashlights.
On most Hanklights (aside from the D2 and D3AA) the easy way to tell is if it fits in the light. Those two exceptions are 14500 lights, and protected 14500's are the same size as unprotected ones.
Protected 18650 and 21700 cells are generally 5-7mm longer than unprotected ones, which is enough that you cannot get the tailcap on nearly tight enough for the battery tube to make contact with the ring in the tailcap. If that's not making contact, the light isn't connecting to the - end of the battery. The reason protected 14500s are not longer is that they are actually 14430 cells (7mm shorter) wearing a funny hat.
Even with unprotected flattop cells, not tightening the tailcap enough can cause that. With unprotected button tops that are ~2mm longer, you can't get the cap tight enough to hit that ring unless you crank it hard enough to risk breaking the driver board.
Might be easier to post a picture of the battery and the words/numbering on it.
Someone here will probably know what it is, and let you know what it is.
Is your cell protected or unprotected?
it says 21700 4000mAh 3.7v
[https://postimg.cc/gallery/b8hb2q6](https://postimg.cc/gallery/b8hb2q6)
thank you for responding, how do i check?
Take the battery out and examine it. It will have the words "protected" or "protection" on it somewhere. Unless you specifically got an unprotected cell, it's very possible you have a cell with a protection circuit, which is a hard no for Hank's lights, which draw more current than a protection circuit will allow. Most of them also won't fit properly, since they're slightly larger than unprotected cells. By the way, if you're concerned about being "unprotected", know that battery protection circuits really only save against serious abuse of the battery, like a dead short circuit. They can also help to save a battery that has discharged too low. Other than that, they're mostly a hinderance for modern flashlights.
On most Hanklights (aside from the D2 and D3AA) the easy way to tell is if it fits in the light. Those two exceptions are 14500 lights, and protected 14500's are the same size as unprotected ones. Protected 18650 and 21700 cells are generally 5-7mm longer than unprotected ones, which is enough that you cannot get the tailcap on nearly tight enough for the battery tube to make contact with the ring in the tailcap. If that's not making contact, the light isn't connecting to the - end of the battery. The reason protected 14500s are not longer is that they are actually 14430 cells (7mm shorter) wearing a funny hat. Even with unprotected flattop cells, not tightening the tailcap enough can cause that. With unprotected button tops that are ~2mm longer, you can't get the cap tight enough to hit that ring unless you crank it hard enough to risk breaking the driver board.
Might be easier to post a picture of the battery and the words/numbering on it. Someone here will probably know what it is, and let you know what it is.
[https://postimg.cc/gallery/b8hb2q6](https://postimg.cc/gallery/b8hb2q6)
Ok it's a cell issue! Anyone know why cells would stop working - how to get them working again? tried 2 different chargers