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post #1 of 15 Old 02-08-2011 Thread Starter
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Alternators..

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post #2 of 15 Old 02-09-2011
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Cheap power is the Holy Grail mate.

Good luck.


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post #3 of 15 Old 02-09-2011
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Originally Posted by chrisncate View Post
How can I utilize an alternator for generating power somehow? I have a bunch of new ones laying around doing nothing (I have acquired them from my line of work - fitness equipment repair), and I'd like to make one or two work for me somehow if it's relatively simple to do so..

Anyone have a good (cheap) idea to utilize one for power generation? I do not have access to a machine shop per say, but I am fairly handy. It seems like wind generators are just alternators on a stick, no?

Ideas?
Not quite that simple, but yes, at least one brand of wind gen is based on an alternator on a stick.

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post #4 of 15 Old 02-09-2011
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Quote:
Originally Posted by chrisncate View Post
How can I utilize an alternator for generating power somehow? I have a bunch of new ones laying around doing nothing (I have acquired them from my line of work - fitness equipment repair), and I'd like to make one or two work for me somehow if it's relatively simple to do so..

Anyone have a good (cheap) idea to utilize one for power generation? I do not have access to a machine shop per say, but I am fairly handy. It seems like wind generators are just alternators on a stick, no?

Ideas?
An alternator requires an initial excitation voltage to charge the windings before it will begin producing power. You'll have to factor that in before you just put one on a stick. Basically, you could feed 12v on the "startup" wire, through a resistive load (small lightbulb) to provide this. Wire in a toggle switch so that the alternator doesn't gobble up your 12v battery when it's not in use.

Also, unless these alternators have an internal voltage regulator, you will need to add one to the circuit.

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post #5 of 15 Old 02-09-2011
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Not worth the hassle - you need a different sort of motor/generator as a starting point. See below.

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What sort of generator should I use?
Most small wind turbines are used for charging batteries, to provide a reliable stand-alone power source where grid power is not available. The obvious choice of generator for self-build is the car alternator. However this has major drawbacks. It must be driven at a high shaft speed (over 2000 rpm) to give full output, so you will need to gear it up or modify it in some way to drive it with rotor blades, which typically only manage a few hundred rpm. This reduces the efficiency. In low windspeeds there is very little power available in the wind, and you need a highly efficient generator to capture it. Most, if not all of the power in light winds will be used up energising the magnetic field in the alternator, so the results are disappointing. Nearly all small commercial wind turbines use purpose-built permanent magnet generators for this reason. The DIY enthusiast can make one too, but this is not simple to do. Or you can reuse a permanent magnet motor as a generator. The generator is the key to success or failure of the project, and by far the hardest part to get right.
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post #6 of 15 Old 02-09-2011
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Some alternators do not need an external source of power to get them going. Does your exercise equipment have a small battery in it, or does it need to be plugged into the wall for external power? An alternator can also have permanent magnets in them that do not need an external source of power. These alternators you have are probably about 30 amps at 13.4 volts (charging voltage for a battery 12 volt battery) as a human can put out about half a horsepower for a brief time, or at least that is what Wikipedia states, but this number varies depending on where you look. A horsepower is about 745 watts and watts are volts times amps so 30 amps multiplied by 13.4 volts gives approximately half a horsepower. It could be that these alternators are not made to run at 13.4 volts. Hook a volt meter to the output of an alternator in one of your exercise devices and put a strong person on there for a brief sprint and see what you get. Set it in the 15 to 25 DC volt range depending on the particular voltmeter you have and try it. If nothing shows, switch to AC and try that. If you get a voltage, then you should probably forget it as you would need to wire up a rectifier that changes AC to DC current (amps), which you can get on ebay for automotive applications. If you get DC volts, then you can consider using the alternator like this: Water Powered Generators with really stiff rope for a torque line and a propeller from an electric trolling motor. Flip the propeller around because you will be pulling power out of the water rather than pushing against it for propulsion maybe you could rig something up.
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post #7 of 15 Old 02-09-2011
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I have heard of a Sea Scout ship that towed a large 3 strand line with a propeller on the end attached to a car generator.
Don't know how much they actually got from it.
It was a large heavy wooden boat, the drag would be more than a sea anchor.
I heard about it because they caught a great white shark with it.

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post #8 of 15 Old 02-09-2011
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I wonder if you could take an electric trolling motor, put a larger prop on it, and generate electricity with it
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post #9 of 15 Old 02-09-2011
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You might be better off using one of the DC motors that are commonly found in exercise equipment, and make a rotor assembly from a flange and pvc pipe. There are a few places on the web that will instruct you how to go about doing both of those things.

p.s. the pvc pipe will be larger diameter (around 6")
p.p.s. There are many ways you could go about this effectively. I see lots of research in your future.
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post #10 of 15 Old 02-09-2011
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i would bet he has perminate magnet generators. they also probably only produce a few watts, just enough to run the electronics on say a tread mill.

if they are what i think they are the best use might be a very small wind genny that will charge a bank of AA recharchable batteries to run say an anchor light ( led ). i would be surprised if they put out more than 10 watts.

maybe mount one on the rail with a line to a dink motor starter battery if you have a battery start dink motor.

or maybe rig up a charger in the boat to charge AA and AAA batteries for radios, head lamps, etc etc
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