Yes, there really are urine-powered batteries out there. But let me ask you something - since these batteries also run on water, what in god's name would bring someone to actually use urine to power these things? I mean, unless you're stuck in the desert, or on a life raft (I'm thinking salt water might be somehow corrosive to the batteries), and you have a desperate need to use something battery-powered (like a flashlight, what were you thinking?), why the hell wouldn't you just use water to recharge?
