Can a spinning motor generate electricity?

[tangerine3]

I had a small 10" household fan that must have developed a shorted motor winding, and began to trip the breaker. I tossed it in my scrap metal pile. One windy day I saw the fan blade spinning from the wind, and decided to mount it on a pole just for fun. Now on windy days it spins like crazy. After a few years outdoors, it became noisy. I guess the bearings were dry, so I oiled them. Now it spins well again.

Anyhow, last week I got to thinking if there was any electric being generated while it was spinning. I put a meter across the cord but read nothing. Of course since this motor was apparently shorted, it was kind of stupid to expect any output power.

However, if I was to take a working fan and do the same thing, would I get any power out of it? A motor is similar to a generator, but is it capable of generating power?

My thoughts are (if this works), are to put a fan outside with a small cover over the motor (to keep water out), connect it to some rectifier diodes, and use it to charge car batteries. I suppose I'd have to rig a voltage regulator too. I'm not sure what kind of voltage would come from a 120v AC motor?

[trader4]

An AC motor relies on generating a magnetic field in the rotor by using the varying AC field in the stator windings. With no AC to generate a magnetic field in the rotor, you might get some small voltage from residual magnetism, enough that you could see it on a VOM, but it's isn't going to produce power to charge car batteries.

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[Stormin Mormon]

Electricity is generated, by spinning a magnet within a coil of wire (highly simplified). If that's a DC motor with permanant magnets, it will generate electricity. Think: 12 volt fan from the auto department of the store.

An AC motor, spun, can also generate electric, but I'm less certain the details.

Christopher A. Young Learn more about Jesus

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Anyhow, last week I got to thinking if there was any electric being generated while it was spinning. I put a meter across the cord but read nothing. Of course since this motor was apparently shorted, it was kind of stupid to expect any output power.

However, if I was to take a working fan and do the same thing, would I get any power out of it? A motor is similar to a generator, but is it capable of generating power?

My thoughts are (if this works), are to put a fan outside with a small cover over the motor (to keep water out), connect it to some rectifier diodes, and use it to charge car batteries. I suppose I'd have to rig a voltage regulator too. I'm not sure what kind of voltage would come from a 120v AC motor?

[Jim Elbrecht]

-snip-

Maybe not a fan motor-- it has to be a motor with permanent magnets. i failed in my search for the Mother Earth article-- but I'm pretty sure there was one - 1975-80 or so.

This guy outlines the process-

[Mr. Austerity]

You are on the right track, but you need to do a little extra work,

Get enough fans running and you can go off grid......

[clare]

Or a multi-phase AC motor with a capacitor across one phase.

[Jim Elbrecht]

-snip-

That's cool-- convert your fan to a permanent magnet 'device'.

Jim

[krw]

With the proper "motor" or some jury rigging, sure, but the more energy you remove, the slower the fan will turn. The reason it's "spinning" now is that there is little energy being removed (just enough to counter bearing friction). Your experiment with oiling the bearings should show you how little energy you can really get out of this.