finding a motor

Discussion in 'Windtura Generators' started by medenlight, May 19, 2009.

  1. medenlight

    medenlight WindyNation Engineer

    after searching ebay for ametek motors the last week, it looks like the going price is around $150 and up. This seems a bit steep for cheapsters like me. a friend used a motor from a treadmill which i see on craigslist in my area for much cheaper. has anyone gone this route. is there a particular brand of treadmill that uses ametek motors? where do all the ametek motors on ebay come from?
  2. PierDrop

    PierDrop WindyNation Engineer

    If you want to go cheap than you hunt on ebay. You need to find a motor that is suitable to be used in a wind generator but is not labeled as a wind generator motor on ebay.

    Here is the trick. Find a "servo motor". 99% of servo motors are permanent magnet motors, which is what you are looking for. If you can find a PM servo motor that has a volts/rpm ratio of 0.03 or higher than you got a good candidate. The next thing to check for is its amp rating. If you can find something that is rated for 10 amps or more than you got yourself a great little wind generator.

    It does not matter if the PM servo motor is AC or DC. We can deal with either of those once you decide on a motor.

    So, search on ebay for "servo motor" and send me a private message through this site if you think you have found something good. I will let you know if it will work.

    And yes, treadmill motors work great. They are also PM motors. Just make sure their volts/rpm ratio is around 0.03 or higher like I said above. Good luck .... building a wind generator is really fun! PD
  3. WindyFAQ

    WindyFAQ WindyNation FAQ Staff Member

    I have a 17A PMA motor that at 2000rpm, gives 50- 60 volt DC current. However, when I connect to a 90A battery, it only yields 13 volt Dc cuurent no matter how fast I turn it. Does your unit help the motor load such that the curent from the motor stays stable to the RPM it's running?
  4. Minnesota

    Minnesota WindyNation Engineer

    I studied 3 turbines with 5-foot rotors to show how important it is to match the PMA characteristics to the blade design. In my video I also plotted RPM vs. Wind Speed. This can give you a sense of what PMA characteristics to look for. Generally speaking, you want one that can reach 12V at a few hundred RPM and then be able to provide 20A at 1000 rpm while connected to a 12V battery.
  5. windyguru

    windyguru WindyNation Expert

    This is normal for all generators that charge battery banks. The battery acts as a very large load with respect to the generator and "loads" the generator down. You do not want the voltage of the generator, which is connected to the battery, to go higher than the voltage of the battery. This would very quickly destroy your battery.

    When it comes to charging batteries with solar panels, wind turbines or anything, you should focus on the amps. This is what is going to determine the Watts and the rate at which you can charge your battery. The voltage will always be fixed at roughly the voltage of the battery bank.

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