Those AA alkaline- and lithium-powered phone chargers are a totally handy (and relatively inexpensive) thing to throw into a bag and carry around in the event -- the incredibly likely event -- that you end up running your set dry at one time or another, but there's a small problem: those AAs don't go very far. Generally speaking, you'll get a couple charges out of a set of batteries, which makes them environmentally dubious at best and less convenient than you'd like them to be. That's where KFE Japan's new solution comes in: same concept, but the batteries are zinc-air instead of alkaline or lithium -- the same tried and true chemistry used by hearing aid batteries -- whereby you pop a lid open on the charger to expose the batteries to air, which starts the juice flowing. The advantage
