Generating electric?

Question

will any 12v electric motor generate electricity .ie to make a wind generator.

Answer 1

A motor and a generator are both electric machines. The only difference is the source of power.

A motor uses energy in the form of volts and amperes as an input to generate mechanical energy in the form of torque. A generator uses mechanical energy in the form of torque to produce electrical energy in the form of volts and amperes.

For a DC machine of fixed excitation (which is most 12-volt machines, by the way, since they're pretty much guaranteed to contain permanent magnets for the field poles these days), the output voltage is proportional to speed. The faster the shaft turns, the more voltage is obtained, since the coils are cutting more magnetic flux paths in a given period of time.

There is a practical limit (defined as commutation capability) that limits the voltage a machine can successfully handle. If the bars of the commutator pass under the brushes too quickly, there is not sufficient time to fully reverse the flow of current in the winding, thereby causing a spark ... and potentially a flashover (where the arc generated bridges from one polarity to the other, or to ground, or both).

Likewise, there is a thermal limitation on the machine winding - i.e. how much current the machine can accommodate without destroying the insulation. This is a factor of the electrical load (impedance) applied to the unit, not the speed.

So - to answer your question - yes, you can hook up a 12-volt motor to a windmill and use it as a generator. Check that you're not spinning too fast and that you're not trying to draw too many amperes ... and away you go!

Answer 2

It will but will have no regulation so depending on what you are trying to power, you may need a regulator or you could produce more voltage than you want. If you are using it to charge a battery, you will need a diode so your battery doesn't use more power driving the motor than it gets.

I'd go for a car alternator, they are cheap and contain all the regulating circuits. Only thing is, you must connect it to a battery for it to give power and many of them also need the light wiring between the small terminal and the big one (Light goes off when charging)

Answer 3

DC motors can usually be used as a generator. Put a DC voltmeter across the leads and spin the shaft to see.

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Answer 4

Yes. Tried it with an old 24v copier motor, friction driven by a bicycle  tyre  , managed to get a 110 v bulb to glow, took a lot of work though.  There is a huge amount of stuff on Youtube.