DC motor as generator.

Discussion in 'The Projects Forum' started by 7yler, Mar 30, 2010.

  1. 7yler

    7yler Thread Starter New Member

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    Mar 30, 2010
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    I am attempting to build a wind turbine, as many have successfully. I have read that a permanent magnet dc motor out of a treadmill will serve well as the generator for the turbine. I'm not very electrically savvy, but I'm attempting to learn. I have posted pictures of the motor, and the multimeter that I'm using. I hooked up the red wire on the motor to the red wire on my meter, and the black wire on the motor to the black wire on my meter. I then chucked the spindle of the motor and spun it in my drill to see if I could get a reading on the meter. I had no reading on any of the "DC V" settings, and no reading on any of the "AC V" settings. BUT, I did have a reading of around 10 on the "12A" setting. I tested all settings turning the motor clockwise, and well as ccw. What does this mean? Am I able to use this as a generator for a wind turbine? :confused: Thanks for any help.
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  2. hazim

    hazim Active Member

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    The motor is rated 7099rpm and 130VDC. 7099rpm is very high for the motor to use it for a wind turbine, except if you will use a gear box or other mechanical way to increase the speed but this isn't good for stability. This motor won't generate even 0.5VDV at low rotation speed like the way you rotated it.

    The rated speed should be about 3000rpm at maximum, the lower the better. The wind will not rotate the turbine at this speed, at this speed the motor generate a voltage near the rated voltage like 130VDC. What happens is that the wind rotates it with a fraction of the rated rpms which generate a voltage around 12V DC, where this output voltage should be regulated and then 12V batteries (best choose are deep cycle batteries) could be connected to be charged.
    I'm interested in building a small wind turbine, actually I want to build one, what w need is a treadmill motor (or similar) with low rated rpm (3000 maximum - it depends on the rated voltage too..)
    I made a research about these small wind turbines that use permanent magnet motors.

    See this web page it's interesting and very beneficial for who wants to build a wind turbine: http://www.mdpub.com/Wind_Turbine/index.html
  3. BMorse

    BMorse Well-Known Member

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    3000 rpm's is still way to fast to generate any usable power from it in a windmill.... you need a Permanent magnet DC motor that has VERY low RPM's (100 to 350) and very high voltage (90 to 130 VDC or higher preferably).....


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    see my Windmill project work log, here >> http://www.morse-code.com/windmill_generator.htm


    B. Morse
  4. hazim

    hazim Active Member

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    BMorse is right, but don't you think a 250VDC 2500rmp permanent magnet DC motor is still good? I think yes.
    A 350rmp 30VDC PMM is a good choice.
    350rmp/30V = 11.7
    3000rmp/250V = 12

    This is why I see it good.. Yes the rpm's are high but also the rated voltage is high as I said.
    Last edited: Mar 31, 2010
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