Turning a treadmill motor by hand with a ratio
of about 5.5....at about 330 rpm it will charge
a 6 volt battery with a reading of about 10 volts.
However for your project I myself would rather
use an Ametek because I think it will charge a
12 volt battery at a much lower rpm.
In fact you would might even need a dump load
controller to keep from overcharging the
battery in my opinion....I may be wrong....
You're on a learning curve and along the way
you may have helped others ....we learn more
by failures than by sucess
Same kind of treadmill motor
http://www.fieldlines.com/story/2005/3/23/225230/317
( :>) Norm