Charging AA Battery with DC Generator
A battery is at least two cells, so what you want to do is charge a cell, not a battery. You'll need a voltage higher than 1.2 volts to charge the cell, and you'll need to limit the current into the cell being charged in order to charge it safely. You can find out the charge requirements by going to the manufacturer's website and reviewing their technical literature. You could also go to battery university, an excellent site for learning about batteries and cells.