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Forum Index : Windmills : small wind turbine motor questions
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| chickenhawk Newbie  Joined: 14/03/2013 Location: CanadaPosts: 2 |
I building a small wind turbine to charge a pair of 12 volt batterys for our remote cabin. And as of now I have a choice of two motors. First is a treadmill motor (specs on motor as of yet unknown) Its still in side of the treadmill. The fellow of is giving it to me has not pulled it apart as of yet. The other motor is out of a electric motorcycle. And it is 750 watt 1 hp 36 vdc reversible 24 amp permanent magnet motor rated at 3400 rpm --36 vdc 2200 rpm --24 vdc. looking for feedback for both of these motors and thoughts on using some type of system to gear up either motor to get more rpm's. |
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Downwind Guru  Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
My crystal ball is broken so unsure on the first motor (Treadmill) the second motor is almost useless as a windmill generator. 3400 / 36 = 94 rpm per volt You would want around 24v at 90 RPM for it to be suitable for a mill (24v mill) Gearing is not worth the cost or effort of adding it as you loose too much efficiency, 1:1 ratio is the only way to go with small mills. Pete. Sometimes it just works |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Yeah those low voltage electric motors are not much good for wind turbines. I spent many hours trying to get useful power from a 24v 300 watt scoota motor, and gave up. The treadmill motor could have some potential, but you will need to know the voltage and rpm before we could tell you if its worth while. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
chickenhawk If you can find a throw-away dishwasher, the water pump assembly has a small motor, which uses a neodymium magnet at its core. You'll have to make an adapter to fit the four-bladed plastic impeller in order to drive it, but that being said, it will put out around 10 volts at normal wind turbine rotor speeds (between 120 and 300 rpm). Of course, if you're not a purist (like me) you could set the blade pitch deep and use a couple of pulleys to get the shaft rpm up and it will put out as much as 20 volts (@ about 500 rpm). It's not the best setup, but it would let you get your feet wet without spending much on all the parts. Just an idea. . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| Georgen Guru Joined: 13/09/2011 Location: AustraliaPosts: 462 |
Would 24V 300W motor be any good for charging USB devices (under 6V)? Could charging something at 12V be still within reason? George |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Georgen, Its best to start your own thread that we can reply to your question direct, without trying to figure out if your current question has any relationship to the thread you posted in. Firstly you need to know what rpm the motor is rated at for 12v and 300w, i can tell you at rated motor rpm you will get around 20 amps into a 12v battery. But that is a bit useless if it needs 3000 rpm to produce that. When used as a generator a 12v motor will need to reach the rated rpm of the motor to produce 12v output, so if the motor is rated as 3000 rpm then it will take 3000rpm input to produce 12v output, not very useful for a windmill as you would want around 80-120 rpm cutin to the battery and not 3000 rpm. For a example if we had a 48VDC motor rated at 400 rpm and 300w and we wanted to use it for a generator for 12v batteries, then the ball park math would be as follows. 400 / 48 = 8.33 (volts per one rpm) 8.33 x 12 = 99.99 rpm (this is how fast the shaft needs to rotate to produce 12v output) 300 / 12 = 25 amp. ( this is the max you can expect under full load and not at cutin speed of 100 rpm) So after all that the short answer to your question is, the motor you asked about is most likely not suitable, but to try to educate you on what to look for is worth asking the question. Pete. Sometimes it just works |
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