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This is a smaller AC servo from the
same robot. The motor was rated
at 130 watts. On the windmill it
pumps out 4 amps into 12 volts.

Servo motor based windmill.  
I picked up this old Hitachi welding robot for a few cartons of beer. The owner was happy to get rid of it, this model was a bit of a beast to operate and very out dated.
I lasercut and welded together a simple platform to hold one of the motors. The platform includes tail furling and bolts to a car wheel hub at the top of my mast. The motor is rated at 1100 watts, so I can expect 500 so watts as a windmill.
A 3 phase rectifier was mounted on the decoded cover on the back of the motor. These motors include a electric brake and opto decoder, both of which have been removed.
Up in the air. There has been stuff all wind since I put the windmill up ( typically ) so havn't got any power figures yet. But the windmill starts up easily as there is no cogging in this type of motor. During the day I monitored the output voltage. Its was just below charging voltage, sitting in the 8 to 12 volt range.

I decided to make a modification in improve output voltage. The motor is wired as a 3 phase star, each leg consisting of 6 1mm wires in parrallel. I seperated the windings and changed to 2 lots of 3 wires in series/parrallel. This will double the output voltage and half the output current.

By doing this the windmill will start charging much earlier in light winds. If this windmill works out, I might play around with a switching circuit to switch back to the original winding configuration as the wind picks up.