We've seen batteries charged by outlets and by cranks, but this concept from designers Song Teaho and Hyejin Lee is the first that charges with a twirl.
However, like all things tagged concept, this battery doesn't *technically* exist yet.
Still, Teaho and Lee both hypothesize that this battery, should it become the real deal, would require about 130 twirls for two-minutes talk time.
From what I've seen of crank-charged batteries, that seems relatively plausible (and tiring). Get to work, fellas. [design(dot)fr via Engadget]