It took about 3 hours of cranking, but I got my phone fully charged. The phone only accepts a very small current (about 94mA in my case), so it's not hard at all to crank. But if the generator leads are shorted out, or hooked up to a re-chargable battery, the effort to crank increases quite a bit! This is because you're pushing more current.
In retrospect, I think it would have been more efficient to spend 15 minutes cranking a larger current into a large 6 volt battery, and then charging the phone from that. But hey, you do what you can with what you have.
The charger illuminated an incandescent flashlight bulb, a super bright white LED, and there was even enough power to convert water into fuel
with the OxyHydrogen generator made in a previous project!