Many designers have explored prototypes along these lines, only to find that there are logistical difficulties making them hard to put into daily use. For disasters or other emergencies, though, this neat little self-contained battery unit would be a handy addition to your BOB (bug out bag) or GOOD (get out of dodge) bag.

One problem is moving parts – regular recharges could wear down the delicately-balanced moving pieces that make the design work. Another is capacity, reduced to accommodate the crank, knob, spring, dynamo and so forth. Yet another is charging time, which would be long if one had to wind it by hand – not efficient for everyday applications – though a regular charging station could be used, too.

These limiting factors aside, though, the design itself is compact and compelling – shaped and sized like other AA and AAA batteries, the winding element folds neatly back into the body so the unit can travel without breakage and be put into ordinary devices. Given how entrenched these objects are in our culture of omnipresent electronics, any solution along these lines has to factor in such standards – and this idea does that well. (Design by?Qian Jiang)