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.

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My test taxes the computer more than a normal user and involves keeping Wi-Fi on, cranking the screen to full brightness, turning off all power-saving features, keeping email retrieval going in the background and playing an endless loop of music.

WSJ: A Laptop Screen That Promises an Eyeful