flashlight

undefined> What if it turns itself on while stored in a backpack?

you are asking the right question

the answer is, do not store in your backpack until you use a strategy to eliminate accidental discharge

on some lights, if the threads are anodised, not shiny bare metal, we can break the circuit by unscrewing the head or tail. So the button will not turn the light on.

to find out if that works with your light, turn it on, and then unscrew either end about 1/4 turn.. If the light turns off and the button does not turn it on, you can now store your light in your backpack safely..

Most flashlights can be safely stored just by loosening the tailcap about a quarter turn.

Some lights have a lockout mode (commonly four clicks of the switch, if it's a side switch/e-switch), which can be handy. Lights running the Anduril 2 (not sure about Anduril 1) firmware by ToyKeeper can even set an automatic lockout timer. But if you want to be 100% certain it's not going to turn on, the easiest thing to do is just loosen the tailcap a bit, which will break the circuit between the battery and the pcb.

There's at least three ways around that. In addition to being able to be locked out both electronically and mechanically, many lights have a switch that is fairly well protected. I may not trust my TS10 rattling around loose/unclipped except in my otherwise-empty watch pocket, but hitting the button on most of my Hanklights is such a low-probability thing that the only light I lockout is my KR4.

It's also worth noting that I have the memory set to "hybrid", so unless I used the light at a high level within the last three minutes, it'll come on quite low in the highly unlikely event that something manages to poke inside the raised ring anyways.