Hello.
I was the other day in a store and I saw a LED survival flashlight that it got power by shaking it.

It looked like that one, just that it had two coils instead of one.
I saw the PCB inside the LED and I could see 8 diodes, a capacitor (I will talk about it later), a red LED and a white LED, and 2 resistors.
I guess the diodes are for rectifying (if I'm not wrong the magnets with the coils produce AC current), but you only need 4 diodes for a full wave rectify, why it had 8?
Each time the magnets went trough the coil the red LED flashed, that easy thing.
But now, the capacitor, I stay looking at it alot of time, I couldn't see any values because the color was diffused, and after a time I star suspecting its not a capacitor. It was kinda axial shape, but it had like a slope in the middle which made me thought it was an inductor, but I don't know.
So if anyone know anything about it I'll appreciate alot

Thanks

 

At a guess, it's a lithium battery. There is a couple of diodes and a capacitor, but the battery does a lot of the work. That is, if it's anything like the one I have.

 

I just looked around on the web and I found that it's powered, like you say, by a lithium battery packed in a button case.
Thanks alot beenthere.