# Building a Wind Generator: How to Choose a Good Wind Turbine Motor

Planning to build a wind turbine? If so, you’ve got some research to do. The most important bit of research to complete is in regards to choosing a motor for your DIY wind turbine.

This can be challenging because you won’t be purchasing something out of a store, where there are knowledgeable people around to assist you. Instead, you’ll be shopping for a used motor on the Internet, where there will be lots of people trying to sell motors that are wholly inappropriate for wind turbine use.

This article is going to tell you exactly what you need, and it is going to give you real-life examples that show you how to choose an appropriate motor.

**The Most Important Fact About Wind Turbine Motors**

There is one important fact that you absolutely must understand before choosing a motor for your wind turbine. The fact is this: wind turbines, and the motors attached to them, spin at roughly 500 RPM’s. Compare this to the generator in your car, which spins at thousands of RPM’s. Why is this so important?

Because if you take a motor that is designed to create 12-volts of electricity at 3000 RPM’s and attach it to a wind turbine that spins at 500 RPM’s you are not going to create any usable power at all, which means that, right off the bat, you can rule out a huge number of the generators that you see for sale on eBay, or other online shopping sites.

**Exactly What You Need**

The best motor for a DIY wind generator is one that produces the HIGHEST amount of voltage at the LOWEST possible RPM’s. That’s a little abstract, so I’ll give you some figures. A good motor will produce at least one volt for every 25 RPM’s. Where do these numbers come from? They are based on the fact that you will most likely be using your turbine to charge up 12-volt batteries, and to do that, you’ll need to be producing, on paper, between 16 and 20 volts.

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Now consider what I told you earlier–that an average wind generator spins at about 500 RPM’s. The math is simple. You get 1 volt for every 25 RPM’s. Your turbine spins at 500 RPM’s. Divide 500 by 25 and you get 20; therefore, you get 20 volts at 500 RPM’s.

**Examples With Real Motors I Found On eBay**

How exactly do you check to see if a motor is suitable for your wind turbine? The first thing you need to do is check the motor’s maximum operating RPM’s and its rated VDC. Then divide the maximum RPM’s by the rated VDC. Here are some real-world examples.

*The Ametec 37*

Ametec, by far, produces the most popular motors for DIY wind generators. Not all, however, work well. Is the Ametec 37 any good? Let’s see. It has a maximum speed of 2100 RPM’s, and it is rated, as suggested by its name, at 37 VDC. To see if this is a good motor, we divide the max RPM’s–2100–by the VDC–37–and we see that this motor produces 1 volt for every 56.8 revolutions. Is this a good motor for your wind turbine? No, a suitable motor, as I stated earlier, needs to make 1 volt for every 25 revolutions.

*The Ametec 99*

The Ametec 99 has a maximum speed of 535 RPM’s, and it is rated at 99 VDC. Is it suitable for our project? 535 divided by 99 equals 5.4, which means this motor produces 1 volt for every 5.4 revolutios. Oh, yes, this is a great motor for a DIY wind turbine. Unfortunately, with such great output, these motors have become very difficult to find, as most have been snatched up by wind turbine hobbyists.

**Final Thoughts**

There are thousands of motors out there being sold to people wanting to make wind turbines. Unfortunately, most of them are not suitable for the job. Neglect to do your research, and you’ll become one of the many who have been duped into buying a motor that is worthless for your purposes. Use the figures and calculations above to research your motors, on the other hand, and you’ll get a motor that’s perfect for your project.