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Generating electricity with wind

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Aug22-13, 10:24 AM
P: 5
I am building a scale model wind farm with 10 Brushless DC motors. Each motor is rated 12v and 1.3 amps. Provided that I can generate 12 V on each motor, what is a realistic amount of power that I can generate?

Thank you.
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Aug22-13, 02:08 PM
P: 576
Lets assume you can get each unit to about 80% of their rated output - 1A x 12V = 12 W, ten units - 120W total.

The real challenge here is to find the optimal way to connect them together to get the maximum harvest. If this is for a school / science fair project, how to accurately measure the power ( Avg and Max) as well as total Energy (WHr) and or demonstrate the work or energy.
Aug22-13, 06:22 PM
P: 5
Thank you for the response. I plan to use a full wave rectifier on each motor and then connect them in parallel. Do you think this is a good way to connect them to achieve max power?

Aug23-13, 08:03 AM
Sci Advisor
P: 1,959
Generating electricity with wind

To get 12V on each motor you will need a significant RPM which will probably require an efficient gearbox. The RPM of a propeller / turbine is proportional to the reciprocal of the number of blades. So the fastest wind turbine will have one blade only, but with two small counterweights that balance and stabilise the rotor. That might help eliminate a gearbox.
Find out what RPM is needed to generate 12V.
Aug23-13, 11:01 AM
P: 576
With DC motors you do not need or want a full wave rectifer ( unless BLDC?) ... realize that each diode the current is flowing through will have ~ 0.7 V drop.... so if the motors are true DC ( just a + & - Lead) - a blocking diode would be helpful to prevent one generator from "motoring" another - but at 12 V you are loosing a significant part of the power, note a full wave will always have 2 diodes in the circuit.... A schottky diode will have lower Forward V drop - these are used in solar arrays, cost more, but more efficent.
Aug24-13, 03:47 PM
P: 1,822
What is the RPM of the motor when 12 V is connected across it?

Do you expect to generate anything close to that RPM with wind? The voltage you can expect from each generator should be approximately equal to the ratio of the RPMs x 12 V.

Have you considered connecting all the generators in series?
Sep30-13, 12:29 PM
P: 5
Thank you all for your responses. The RPM for the motor at 12 V is about 3000 RPM. I have tested the motors with the exhaust of a vacuum cleaner at with wind at about 30 MPH. I will try the schottky diodes and see how they work.

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