McNierney acknowledged that most customers may bypass the hand cranks but he insisted they are usable. (Six minutes of hand-cranking should produce an hour of run-time.) To test the feature, the organization took out the tablet batteries to see whether the devices could run just by hand crank.

FORBES: A Look At OLPC's XO 3.0 Tablet's Solar And Kinetic Chargers

That chip, along with the custom charging circuitry developed by OLPC and Marvell means that the tablet can be charged by a hand crank at a 10:1 ratio (10 minutes of usage time for every minute spent cranking), or by the optional four watt solar panel cover at a 2:1 ratio on sunny days.

ENGADGET: OLPC's XO 3.0 tablet hands-on (video) Hands-on