Why no protection circuit in flashlights?

I’ve been looking at several 18650 flashlights, and even when they’re like $50 (expensive by my standards), the lights don’t have protection circuit built in to prevent over-discharge. Why is that? Doesn’t it make much more sense to add the protection circuit into the flashlight so batteries (the consumable part) can be inexpensive, rather than have to buy protected 18650’s?

I’m sure most lights have it. Maybe it’s just not listed.

i am not sure which lights you looked at, but pretty much most (if not all) of my lights have over-discharge protection. The light starts flickering around 2.9-3.0V and then turns itself off. Or something like that.


I have bicycle lights from Fenix (bc30) and Acebeam (bk10). Both recommend using protected cells. I had assumed that was because the lights themselves lacked protection. If that’s not the case, why recommend protected cells (which are much more expensive)? An abundance of caution? Or does the protection in the cell confer some additional advantage?

I’d very much like to use unprotected cells in these lights, as I do with my Zebralights.

I think they are being cautious. two protection circuits may be safer than just one.

Most Fenix lights only work will button top cells, and since many of their buyers probably aren’t even aware that button-top unprotected exists simply saying “protected” is the easiest way to explain it.

Also some lights designed to work with both li-ion and CR123 primaries may not have LVP. This is to allow running the CR123 cells all the way down.

The Fenix BC30 can be used with CR123 cells. I’ll continue to use protected cells in that light. Thanks for the information.