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Discussion Starter #1 (Edited)
Hi guys,
My son picked up a automotive alternator type windmill and we set it up on the workbench just to see
how it worked, We just hooked up a test light and soon as it starts to move the light will come on.
Dim if its turning slow But really bright if you spin it fast. This is an automotive alternator that has been
converted for windmill use. You can get just the kit and do it yourself. And I'm not sure but I bet you
can also get the brackets and fan blade separate and build one pretty easy. This looks like an old school GM part.

The blades are fiberglass or plastic very light weight

Note we didn't get any instructions with this anyone know if a controller is needed? (I'm thinking yes)
It doesn't look like it but the blades were spinning when this picture was taken



 

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most gm alternators have a built in controller, id spin it at different rpm by hand and check with a multimeter and check the voltage outputif should stay around 14 which would be ok.
 

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If its a GM its an AC/Delco. I've one I used to make a DC genset powered by a 6.5hp gas engine & had to instill a voltmeter to it. I was told it was needed to set the polarity of the output but not all of them need it.
 

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Next question is this... Based on the size of your blades, how much minimum wind (MPH) is needed to get consistent voltage? How much wind gives you maximum voltage? And is it possible in a storm to OVER SPIN the alternator and ruin parts of it?
 

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Discussion Starter #5
Next question is this... Based on the size of your blades, how much minimum wind (MPH) is needed to get consistent voltage? How much wind gives you maximum voltage? And is it possible in a storm to OVER SPIN the alternator and ruin parts of it?
I don't have a clue,, But I am a curious as you we stuck it outside on a pole with a light on it just to see.
And I don't think it can be over spun.
I was looking inside this alternator from the back and the built in voltage regulator is gone so I'm thinking that it is going to
need controler. I bet if it spins fast it will burn out the 12 volt bulb that we have hooked to it. On the workbench the test light
would get super scary bright just from giving it a good whip just by hand.
The manufactures name is on one of the blades I'm going to look them up and see about getting the instructions
 

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Next question is this... Based on the size of your blades, how much minimum wind (MPH) is needed to get consistent voltage? How much wind gives you maximum voltage? And is it possible in a storm to OVER SPIN the alternator and ruin parts of it?
Size of the blades, number of blades, blade shape, blade material, and torque needed to turn the alternator all play a part in wind speed needed.

Generally speaking, bigger blades should require less wind.

Lighter blades have less mass to get going, so should require less wind.

The torque mostly depends on the size of the alternator, but can also be affected by gearing. If you gear up to get higher RPMs at the alternator, it should take more torque and higher wind speeds to start.

The actual speed needed depends on a lot of factors. Manufacturers make systems for low wind, medium wind, and high wind applications. Example...

The Primus Wind Power AIR 40 is designed for medium to high wind areas. It has 46" diameter blades, starts generating in 7 mph winds, will operate in up to 49 mph winds, will survive 110 mph winds, and uses an electronic torque regulator as overspeed protection. This is basically an electronic brake. Optimum wind speed is 10-49 mph. Costs about $900

The Coleman 600W Wind Turbine is designed for low wind speed areas. It also has 46" blades, starts at 4 mph, and can charge 12 or 24 volt batteries with its auto-detect charger. I've seen these on sale for around $500, list is about $650.

And yeah, it's very possible to spin a home-made turbine so fast it destroys itself. Commercial models usually either auto-furl, have a torque limiter (electronic or mechanical governor), or use a take down pole or tower so you can get it out of high winds.

For more info, you might want to look at...

Home Power Magazine - Wind Power Basics
 

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Discussion Starter #7
I found some information on this windmill. I thought it would need go faster than this


This is definitely going to need a controler
 

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Harder to build, but you might look into the benefits of a vertical axis turbine design. They take less wind and make better use of winds that constantly change direction.
 
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Discussion Starter #9
Harder to build, but you might look into the benefits of a vertical axis turbine design. They take less wind and make better use of winds that constantly change direction.
I'm thinking of letting my son take take charge on this project I got too many irons in the fire now.
I'm trying to figure out how to wire my solar power into the house circuits,,I think I like the solar better
than the wind power.
 

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That thing needs a ratio amplifier. Any type pulley system to get atleast 2:1 & 4:1 would probably best. Get higher then that & you may loose the torque to turn it. With a 2:1 means need only half the rpm to get a useable output.

I suspect that chart posted isn't accurate as its for a certain alternator/generator.

If you use bicycle sprockets & chain you will more then double your required maintenance. Pulleys with V-belt such as salvaged from a riding mower deck would be a better choice.
 

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Here is one way you could use it, . . . would not cause burned out bulbs, . . . would not be dependent upon wind speed.

Hook it to a battery bank, . . . battery bank to an inverter, . . . inverter to 110 volts for lighting, etc.

May God bless,
Dwight
 

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I think I like the solar better than the wind power.
I think a hybrid solar/wind system is just about ideal. When the sun's not shining it's usually windy, so you will get something coming in, even at night. That's the way I'm gonna go too.
 
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Discussion Starter #13
That thing needs a ratio amplifier. Any type pulley system to get atleast 2:1 & 4:1 would probably best. Get higher then that & you may loose the torque to turn it. With a 2:1 means need only half the rpm to get a useable output.

I suspect that chart posted isn't accurate as its for a certain alternator/generator.

If you use bicycle sprockets & chain you will more then double your required maintenance. Pulleys with V-belt such as salvaged from a riding

mower deck would be a better choice.
The chart you see is for this windmill. I found the model of this and who sells it.
It's not a car alternator anymore it now has permanent magnets inside. Just about everything inside has been replaced
with after market windmill parts. When you turn it over by hand you can feel the magnets grabbing and releasing
 

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In most cases, alternators need to turn at 800 RPM's minimum to generate a steady current. However, this will not be it's maximum current rating; 1200+ RPM's will produce that (most of the time).

It is now converted with PMG's, cool! That means you do not have to have a battery attached to excite the rotor; raw power from EM.

Now, if this alt can produce 60amps DC at 1200 RPM, and you are going to invert to 110, remember that you will lose a lot of power to the inversion process (heat) and of course, you will have to account for the PF (power-factor loss/inefficiency) of ~20%..... now the math

- 12 VDC inverted to 110 VAC is an 8.09 dividend (110/13.6)
- 12 VDC @ 60A = 720 Watts

So... 110 VAC inverted produces 5.94 Amps (110/8.091)*.8 )) -or- 522.7 Watts (5.94*110_*.8))

These are your final numbers after accounting for a .8 power factor/ efficiency loss. For you alt, just replace the '60' amp number with your number and there you go.

Hope this helps.
 

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Next question is this... Based on the size of your blades, how much minimum wind (MPH) is needed to get consistent voltage? How much wind gives you maximum voltage? And is it possible in a storm to OVER SPIN the alternator and ruin parts of it?
There have been engines that turn 9000 rpm and an alternator doesn't get over spun. (Remember the reduction in gearing. At 9000rpm the Alternator is spinning real fast) I doubt the wind would be able to over spin it.
 

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OK, let's clear up some misconceptions.

1. a diode doesn't require any power to prevent flow in the opposite direction - no power loss there.
2. a diode has a voltage drop of between .3 and .5 volts depending on the material with which it is made.
3. The job of the alternator is to charge the battery after the engine is started AND supply the power necessary to operate all the electrical gear on the car at the same time.
4. permanent magnet alternators do not require any outside power to generate power. It IS a generator that generates alternating current - all alternators are AC generators. They can use a small amount of power to energize the field coil (in the rotor) if they do not have a PM field.
5. a 100 amp alternator uses just slightly more than 1.7 HP to produce the full 100 amps of which it is capable. There is a direct relationship between HP and watts - you can figure it out and add 10% for losses.
6. the regulator in an alternator is a governor. It samples the OUTPUT voltage and shunts power or decreases the field strength when the output voltage goes above a certain point. There are only two wires necessary to make the alternator work. One is a wire connected to the ignition circuit - to energize the non-permanent magnet field (not required with a PM field alternator) and the wire that connects the alternator output to the battery - that one has diodes that prevent discharge as a secondary function of being a full wave bridge rectifier that turns the AC current into DC current to charge the battery and run the entire electrical system of the car.
7. Above 2400 rpm (alternator shaft speed) the alternator produces its maximum current output. If you bypass the regulator the voltage will climb to over 90 volts and the current will remain the same. When converting an automotive alternator to use in a wind generator the voltage regulator is often removed and placed at the battery to prevent losses in the wires from the alternator to the home.

The windmill will have to produce about 2 HP to power a single 100 amp alternator - you will have to use a speed multiplier (chain and sprocket, gears or a belt with the appropriate sized pulleys) to get the speed you need. From a single vertical windmill you can drive up to three automotive alternators. The old Aero-motors produce lots of torque but don't make much RPM and they are less efficient that a three bladed horizontal wind turbine of similar diameter.
 

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FWIW, my sister-in-law is a big shot at a company that makes alternators and starters. Last year they were working with a company out east that manufactures a vertical windmill and wanted my sis-I-L to come up with an alternator. I e-mailed her for any info and will share if anything came of it.
 

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The AC current produced by the automotive alternator is converted to DC by the use of diodes IIRC, is it possible to convert one to produce AC current by removing the diodes? If so how hard would it be to regulate the voltage?
 

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It is not just a matter of regulating the voltage, with AC current you are getting 3 phase AC but the frequency (60 Hz) changes with the speed of the alternator. You can carry the AC current from the alternator into the house and connect it to the rectifier and regulator and use it to charge batteries and the run an inverter off the batteries. It would be very difficult to use the 3 phase AC from the alternator with any household electrical appliances. It simply would not be worth the cost.
 
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