how to make a dynamo battery charger?

i settled on using my old drill as a generator but the power just goes into the drill instead of the batterys do i need a diode and what sort?
by the way the drill is 12.5v

Re-design8 years ago
YOu have to use a diode in line with the battery to prevent the powerthat you're trying to force back into the battery from pushing it's wayback out and trying to make the generator into a motor.
sharlston (author)  Re-design8 years ago
pointing towards the battery?
The arrow should be point to the pos. term of the battery.