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I had a shake-to-charge flashlight once. The movement to charge it would get you arrested for indecent exposure in the South of the US. OTOH, But it worked beautifully, and, yeah, no batteries needed.

I'm guessing these batteries are the same thing.

The shake-to-charge flashlights appear to be a long tube with a coil of wire wrapped around it at the middle, with a permanent magnet with soft bumpers able to slide up and down the tube. You can feel the bump when the magnetic field hits the coil; I'm guessing that the rest of the circuitry consists of a bridge rectifier and a capacitor. (And an LED, of course.)

Presumably in the "battery", the LED is replaced with a power supply that can boost 0.8V or whatever up to 1.5V, or reduce 2V down to 1.5V when needed.

I have a crank-to-charge flashlight and I love it. Thirty cranks will run the flashlight a good ten minutes or so.

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