Now all the bases are covered.
I once had a 'novel' flashlight that you would shake back and forth and the magnet oscillating in side would charge a batter or capacity - whatever it was. It was the "Shake-weight" before shake weights existed. Basically a gag gift for a birthday, but it actually was useful several times. Impressed some foreign exchange students who had car troubles.
While it would take a while, this is a viable way to re-charge rechargeable batteries... you and gravity are the inputs. Might take 5 years, but ....