I have just acquired a DC motor from a treadmill. The specs on this motor are: 3200RPM 32.5amps 90VDC I'm wondering how good this motor will be for a wind generator. I'm new to the boards and building wind generators and would greatly appreciate some input from people who know what they are doing. One of my questions is how do you keep the voltage constant while still getting more Watt's from it. Also wonder what sort of wattage I can expect out of this motor at different RPM's. Also wonder what wind speeds would be required to push this motor to sufficient rpms to generate at least 12volts.
This would make an OK motor for a wind generator. Your "cut in" wind speed is going to be fairly high because of your volts to rpm ratio. Probably around 12-13 mph wind. The load will keep the voltage constant. As long as you are hooked up to a battery bank, you are not going to exceed the voltage of your battery bank. Therefore, the only way you can get more volts at a given wind speed is by using a higher voltage battery bank. But because your motor will have enough trouble getting to 12 volts, a 24 or 48 volt battery bank is not an option for you. Your wattage produced depends on your load. But, I would guess that motor could put out a lot of amps in good wind. I would not be surprised if you saw 15-20 amps in 20 mph wind (180-240 watts). Maybe even more but you will not know until you test it.
Would I be able to gear the generator say 2:1 and if doing so would it decrease the amount of wind needed to spin it fast enough or would doing so actually increase the amount of wind needed? Also is there anyway someone could maybe give me a link to a motor that would make a good generator that can still be found for reasonable price. Maybe an ebay link of an item that would make a good windmill so I have an idea what is really needed to make a good generator for this purpose. Seems like many are building their own generator wondering what kind of power you can get out of a home built system in sub 12mph winds. Also this site seems fairly new or just lacking in how-to's is there another good go-to site that has more information on creating your own wind turbine? I have found some but when you google search many of the sites end up leading you to one of the alternative energy book sites.
