The Forever Flashlight uses the Faraday Principle which states that when an electric conductor, like a copper wire, is moved through a magnetic field, electric current will flow in the conductor. The Forever Flashlight then stores the charge in its capacitor, and uses it to power its super bright blue tint LED. This means that 15-30 seconds of shaking (there-by passing a magnet through a copper coil) gives you up to 5 minutes of continuous light, and best of all, you will never have to buy batteries or a replacement bulb. The Forever Flashlight is completely waterproof and even floats. It is not affected by cold or hot temperatures making it a reliable source of light whenever you need it. The Forever Flashlight comes in two sizes. They both have the same brightness and can be seen up to a mile away, however, the Forever Flashlight Jr. does have a smaller diameter, and thus has a smaller “light spot”.
NEW YORK – There must be some unwritten law that requires flashlight batteries to either be low on power or nearly dead just when blackouts hit. Or, for that matter, any other time a flashlight would be nice to have.
– A Flashlight That Goes On Forever by Arik Hesseldahl Forbes.com