Rechargeable batteries can be a bit of a pain—you have to carry around an adapter, find an outlet, and even bend over to plug in the adapter. It's hell, really.
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The SunCat batteries solve all of these issues while giving the environment a firm pat on the butt by wrapping standard NiMH rechargeable batteries (1.8V) in photo voltaic cells (1.5V). Seen in prototype form here, each battery becomes its own solar trickle charger, constantly topping off its power reserves without ever over charging.
Now if only Duracell, Energizer or some other major manufacturer could swoop in and mass product this idea... [Notes from Knut via OhGizmo!]