Not really Mike, But 6+ volts is what most treadmill motors will produce in the 400 rpm range (approx), that is the typical speed of a 4 ft diameter propeller.
The Ametek is the better motor of choice for 12v cut in at around 400 - 500 rpm
Mike. You have to be generating just over the battery voltage for a charging current to flow. For a 12v system, 12+ volts is required - 6 volts will do nothing.
Your 4 Foot blades would really struggle to spin the future energy alternator. Your best option is to get hold of an Ametek 30 or 38 volt motor.
ben thanks for your help on this one, but a few more questions really. Ive measured my blades and they are a touch over 5ft(not 4 as i originally thought) so would a future energy alternator work. If i did use an ametek or similar are the motor bearings good to take the load of the blades, as they weigh about 1.5 kilos) or do i need to fit another bearing on the shaft to take the load. BTw the bladess are made by peter in cornwall and are very good. arec there anyn other alterators that might do the job thanks again mike