If this has already been suggested, then accept my apologies...
My daughter has an LED flashlight that has a small handcrank attached. At night when I turn out the light, she winds it up and leaves the light on while she falls asleep. The light is usually just fading out when I come in to check on her before I go to sleep.
So, my suggestion is for cell phone batteries to have a small handcrank added to them so that you can add just a little power to finish your call, get home from the cottage, arrive at your hotel, whatever. I don't usually have my AC charger with me, I don't own a DC charger, and the USB charge requires me take out my laptop. Anyway, you aren't always near an AC or DC outlet. A small crank to add a few minutes of talk time or an extra hour or so of standby would be very useful. I'm sure it could be designed to fold nicely away so that it doesn't negatively affect the form factor. Most cell phones are too small these days for comfortable use, so I'm sure there is room for the requisite hardware to implement it.
Actually, on further reflection, perhaps Blackberrys could leverage the near constant rotation of the thumbwheel to charge the battery. Other phones could just add a similar wheel just to add charge...-- wuj3888, Oct 27 2008 cnet reviews of two crank chargers http://reviews.cnet...88_7-6427792-2.htmlThis is the form factor that this normally comes in - as an add-on charger, not built into the phone or its battery. [jutta, Oct 27 2008] I'm sorry I misunderstood your invention. I thought you created a way to "Wind Up" your daughters conversation on the cell phone before the minutes sent you to the poor house. Now that would be an invention.-- theGem, Oct 27 2008 :-) My daughter is only 8, so not really a concern yet. But, you could modify the design so that the requisite generator also acts as a motor, throw in a remote control feature (perhaps web based and triggered by preset usage levels..?) and drain the battery as she talks to avoid those overage charges...-- wuj3888, Oct 27 2008 Giving a whole new definition to crank calls, eh?-- jutta, Oct 27 2008 Is this a wind up?-- skinflaps, Oct 27 2008 random, halfbakery