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How would I go about making an alternator? Answered

I was thinking about making a small wind mill to charge my ipod and phone. Unfortunately, I have no idea how to do this. My dad says that I could reverse the magnets on a fan and that if the fan blade spun, the power would go into what ever I wired it up too. Would this actually work?

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H3onnici (author)2009-10-09

"Using a battery to power an electromagnetic field, and then use the current generated to continue powering the electromagnetic field,as it would be generating other current too to charge an other/same battery"

That is exactly what most Car alternators do (The self exited models)...infact they usually run on basically 3 wires....
B+ the 12V + of the battery
B- the ground of the battery
and
D+ .... this is the wire that gives a little current on the coils so that current may generated as the alternator turns...(this is connected to the B+ too of the battery, as when the generator would be producing [inducing] current, the same current is used instead of taking more current from the battery)

Alternators are very good for this particular applications... you would have to continuously connect the battery to the generator when you want to generate current (but don't worry the D+ takes only some Milli-amps so it surly won't discharge the battery) it would take months to discharge, with no generation at all.
The same current generated would charge the battery.

Then just connect a cigarette lighter to the battery terminals, and connect the cigarette charger provided with your mobile,mp3 player, or any other device to charge it.

This has an extra advantage, even when the windmill (wind turbine) will not be turning, the device still charges off from the battery. The battery itself could than charge later as the windmill turns.

Hope it was helpful :D

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bikerbob2005 (author)2008-09-06

a permanent magnet motor is the same thing as a generator generators do not make power at low RPMs that said if your motor is a 2300 RPM then spinning it less than that will not produce anything (ok a little varition think if the motor only got 80 v insted of 110v) an alternator makes alt current by enegersine the feild of the coils ,can find realy small ones on some motorcycles ,it makes power at very low RPMs it peeks Amps at top RPMs. the toyodas back in the 1970s had small alts on them that were only like 35 amps at 12VDC ie 420 watts they needed to turn 1000 RPMs to make 12 amps less than 500 RPMs no power output . hope this helps.if more questions drop me a message.

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chuckr44 (author)2008-09-04

I believe otherpower.com has plans for making an alternator to generate electricity from wind power.

For the easy route, simply use a DC motor. When a DC motor is turned it generates DC power on the contacts. I tried it and it works!

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chuckr44 (author)chuckr442008-09-04

DC motors are motors found in battery powered devices. I also hear tape drives contain DC motors, but my source did not say if this was a computer tape drive, or audio tape cassette drive.

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Rishnai (author)2008-08-19

It will work great. A motor with current applied creates motion. That same motor with motion applied creates current. I don't know about this whole "reverse the magnets" thing, though. Does he have any particular reason that that would be necessary?

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NachoMahma (author)Rishnai2008-08-19

. Not all motors will work. Most home fans won't work. Most AC motors won't work. Most motors with permanent magnets will work. . Put a voltmeter across the motor leads and spin the shaft. If you get a reading, it will probably work.

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Rishnai (author)NachoMahma2008-08-19

Excellent addition. That's an aspect that ye olde science teacher didn't mention to me. What is the difference, specifically, that make AC motors unsuited for generating?

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NachoMahma (author)Rishnai2008-08-19

. It's the permanent magnets. Most AC motors depend on an induced magnetic field and don't have magnets.
. Googling "induced magnetic field" +"AC motor" will explain it better than I can.

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Rishnai (author)NachoMahma2008-08-20

Good to know. I wonder if you applied a starting voltage to start it, then mechanically spun it, if the magnetic field would self-sustain and give a useful output, due to the armature sweeping past the permanent magnets?

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NachoMahma (author)Rishnai2008-08-21

. I suppose you could use a battery to power electromagnets (in place of the permanent magnets) and once the generator started producing power, use the generator to drive the electromagnets. I have no idea what it would take to power the magnets - it may require more than the generator would produce.

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Rishnai (author)NachoMahma2008-08-23

There's probalby a critical rpm, below which the magnets would not be powered. This bears experimetation by someone that's not me.

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Alexforprezzz (author)2008-08-20

I see, and I would I reverse the electrical flow?

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Rishnai (author)Alexforprezzz2008-08-20

I don't know. A battery would probably do the trick. Then once it's started spinning, apply mechanical force and disconnect the battery. Make sure you use a rechargable. I don't have an AC motor handy, but I have a professor who does, I'll ask him tomorrow. Maybe I'm spitting in the wind.

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Alexforprezzz (author)2008-08-20

so this won't work with this fan? would I just need to go out and find an alternator off of a blender or something that spins?

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Rishnai (author)Alexforprezzz2008-08-20

A blender plugs into AC mains. Get a DC motor, like out of an RC toy.

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