300 Watt Permanent Magnet DC Pulley Generator 3/8" V-Belt Drive Pedal Power Pulley Dynamo with air ventilation holes PPG-PM300-P

You can save more than 50% by making your own. Do an Amzaon search for "MY1016" scooter motor and a search for 2" V-belt pulley 5/16" bore. Or you can do a search for amazon product code "B00T6CKSGY"

It may be a big surprise, yes any DC permanent magnet motor also works as a DC generator. The MY1016 scooter is very robust engineered to operate in harsh conditions. It has ball bearings on its shaft as opposed to brass bushing bearings which are found in most cheap motors.

To make your own, the basic steps are: (1) Remove the nut and gear off of the MY1016 scooter motor (2) Measure the shaft of your scooter motor (Usually 8mm). (3) Drill out the 5/16 inch inner bore pulley to meet the size requirement mentioned above (4) Grind a flat spot on the shaft of your scooter motor / generator where the set screw from the pulley can rest. (5) If you are really ambitious, you can take the MY1016 permanent magnet motor apart and drill holes in the sides to allow cool air error to enter so it doesn't get too hot while running at 15 Amps output or more. It is very difficult to put it back together because the brushes that touch the armature are spring loaded and get in the way.

NOTE: The generator shown in this listing has already been modified with these ventilation holes for you.