If you’re at all interested in experimenting with alternative energy, you’ve probably heard that if you take an electric motor and apply some kind of a force to it to spin the shaft, electricity will flow from its wires.
Most people who consider building a wind generator or some other form of electricity generating experiment think that a car alternator is the perfect type of motor for their projects. While car alternators can be used successfully, they’re probably not the most efficient type of motor for most applications. The reason for this is that an alternator needs to have electricity to generate electricity.
Sound confusing? Well it’s really not. You see, an alternator like you might find under the hood of your mini van requires 12v power which transforms the coils of wire inside the alternator into electromagnets. When the alternator pulley is spun at a certain speed, electricity is produced. The main thing to remember is that no 12v electricity going in = no electricity being generated.
Why Use A Permanent Magnet Motor Instead of a Car Alternator?
If alternators consume electricity while they are generating it, they can’t possibly be as efficient as using a permanent magnet motor (PMM) is when generating electricity. These motors are just what they sound like. Instead of them being constructed in such a way that they require an inflow of electricity to power the electromagnet, they have permanent magnets in them. If you spin the shaft on one of these motors, electricity will instantly be produced but they won’t consume any power while doing so.
My husband recently bought our very first PMM on eBay for about $40 so that we could start building some of the experiments that we’ve been wanting to make for so long. The motor that he purchased was supposedly a motor from a large computer tape backup drive in its earlier life. It was made by a company by the name of AMTEK and it is their 30VDC model.
Expectations of The AMTEK 30VDC PM Motor
According to www.tlgwindpower.com, a company that makes rotor blades for home built wind turbine products, this motor should produce 18.5 volts when the shaft is spun at 550 RPM’s. This source also says that it puts out 5.3 shorted amps at this shaft speed. We’re just beginning our experiments so I don’t know if “shorted amps” is different than “usable amps”. I’ll have to look into that.
I’m excited to have the motor and looking forward to the things that we’ll learn from the experiments that we’ll do with it. Here’s a photo of the motor. Note that it’s mounted in a crude bracket that my husband welded up for testing purposes. He made it out of some square steel tubing and an exhaust clamp that he had laying round.
Just so you have an idea of scale, this motor is 4 inches in diameter by roughly 5 inches in length and it weighs about 8 pounds. The shaft is 5/8 inches in diameter and about 2 inches long.
I’m sure you’ll be hearing a lot about this little motor in the months to come because we have some big plans for it! Stay tuned for more…