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Picture of DIY 1000 watt wind turbine
We built a 1000 watt wind turbine to help charge the battery bank that powers our offgrid home. It's a permanent magnet alternator, generating 3 phase ac, rectified to dc, and fed to a charge controller. The magnets spin with the wind, the coils are fixed, so no brushes or slip rings necessary.

Update: DIY Amp Hour meter for monitoring charge!

All about homebrew wind and offgrid power systems, the complete reference!
 
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Step 1: Build the magnet disks

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We had 12" steel disks hydro cut. We cut a template for mounting the magnets. Then we mounted 12 grade n50 magnets around the outside edge. We then built a form, and poured the resin with hardner.

Step 2: Build the coil disk

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We wound the nine individual coils, soldered them in a 3 phase wye configuration, and encased them in resin. We used 35 turns of 2 parallel strands of 14 gauge enameled (magnet) wire for 12 volts. Use 70 turns of single strand for 24 volts. # 3 phase diagram shown here shows 3 stator coils. each of those coils is actually 3 coils in series. coils 1,4, and 7 are series together, 2,5, and 8 are series together, and 3,6, and 9 are series together.

more details, see the following page 15 for the series star, 1-y diagram.

http://groups.yahoo.com/neo/groups/axialflux/files

AXIAL_FLUX_HowItWorks.pdf

Step 3: Build the bearing assembly

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Two Harley Davidson wheel bearings are inserted into the pipe, with a smaller pipe locked between them to keep them in place.

Step 4: Construct the blades

The blades are 2" x 6" pine, cut at 10 degrees on a table saw, and sanded into a rough airfoil. Not perfect, but close enough.

More can be found at

http://tech.groups.yahoo.com/group/axialflux/

http://www.green-trust.org

http://youtube.com/watch?v=o9EEHFKEckM

Step 5: Further Reading

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lr10cent8 hours ago

Probably someone already said this before, but it seems to me that shaping the blades better could make a big improvement to the turbine's performance. I doubt it would be very hard to do, with a bit of patience. I think there's a fair amount of info out there on airplane props, though for turbines you'd want to invert the airfoil. Also, at wind turbine speeds the airfoil might need to be a bit thinner where the blade is narrow. Or else the blade might be best if not tapered quite so much. OTOH, if the prop tips are going Mach 0.5 or something, maybe the prop airfoils would be just fine. (For example, 1,000 rpm on a 10 foot turbine)

sspence (author)  lr10cent7 hours ago
This is a 650 rpm machine. you could work more on the shape, but for little gain. perfection is the enemy of good enough.
What kind of winds would generate 650rpms, and how much actual charging time would happen at an average daily wind speed of 10km/h?

Wouldn't take a lot of work to shape the blades better. But I'm not sure it would help a lot.

I'd approach it differently though. I'd just use a large brushless motor from an RC plane. Add an oversize prop (so the wind could drive the motor better) and a 3-phase rectifier "bridge"
These motors are so cheap now that it isn't worth the effort to wind your own, which is what they did here.

Might be fun to make a "windmill" that looks like a fighter....

You may be interested in looking up the NACA wind turbine airfoil catalog. An ENORMOUS amount of research has been done and is available. I believe there are even 'self stalling' airfoils that lose lift when the maximum rated tip speed has been exceeded. A very desirable trait when high storm winds are gusting. Maximum efficiency is achieved not by impulse energy (air deflecting off of the bottom cord) but by the lift generated over the top cord. The airfoil will be pulled forward by the vacuum effect of the lift generated. Hope you find this helpful.

I'm sorry, but i'm disappointed.
AndyB27 hours ago

great project. I am impressed by the number of views!!

sspence (author)  AndyB27 hours ago
I'd like to know how many actually went out and built one :-)

You can't do it from the information given. You need to join their group or pay a subscription fee. Then you get the information.

If you want the complete information free written by Hugh Piggott who has many years experience doing this then here is his pdf.

https://practicalaction.org/docs/energy/pmg_manual...

DennisS44 hours ago

I agree with Jemurray976 ...This is not a DIY - it's an advertisement to buy the DIY document. My understanding was that this is a place to share knowledge not sell it, if this is true then agreed, this advertisement has no place here.

jemurray9764 hours ago

This is not a DIY - it's an advertisement to buy the DIY document. It has no place here.

A very good reference source can be found with 'Hugh Piggott'. He's in Scotland and is kind of a guru on this subject.

I am a big believer in tapered roller bearings as they take both axial and radial loads. If anyone can point me to a reference for fitting them into pipe with minimal or no machining I would be grateful! Nice 'ible.

I sealed all open areas on the bearing with oil based sculpting clay. Make a cardboard box mold. Cast mold with eurethane rubber. Cast high temp epoxy. Epoxy washer on as a pipe stop.

tcarney578 hours ago

I didn't catch what kind of resin you used for encapsulation, but I've heard that both polyester and especially epoxy degrade in sunlight. Ordinary exterior or marine-grade paint is often suggested to protect them. Here's what West System says about their epoxies: http://www.westsystem.com/ss/finish-coatings/

sspence (author)  tcarney578 hours ago
We coated with bondo, but any automotive paint will work fine.
Tenire8 hours ago

This is a way-cool project you've created here. I have to wonder, though, how much difference the solid enameled 14awg would be from THHN 14awg in this application. Also, do you think it could be turned vertical and made into an omni-directional wind genny with spiral blades?

sspence (author)  Tenire8 hours ago
You could turn it vertical, but you would lose a lot of power. This is a omni directional wind turbine, It turns into the wind at speeds under 30mph.
sspence (author)  Tenire8 hours ago
to reduce coil size, enameled solid copper is traditionally used for motor and alternator windings.
JohnN39 hours ago

Last I knew Ohm's law states P=IE. That means at 12v to get 1000w 83 amperes of current would be required. I'm curious as to how you came up with a calculated 1000 watt output.

sspence (author)  JohnN39 hours ago
You are correct. 1000w / 12v = 83 amps. For the 24v version, 1000w / 24v = 41 amps (rounded down). So when my meter is reading 83 amps on the 12v version, or 42 amps on the 24v version, I know I'm making 1000w. This is not rocket science. The diodes are rated for 150 amps, so we are covered.
JohnT124 months ago

I'm curious as to how you determined that this is a 1000 watt generator. I'm working on a small model right now and am not sure what I'll get from it when it's done. About 5 inches in diameter.

I must also say that I've given up completely on lead acid batteries. When yours give up the ghost, check out LiFePo4 cells.

sspence (author)  JohnT124 months ago
Ohms law. number of coil turns, wire gauge. rpm. blade length, wind speed.

Not interested in Lithium based batteries. NiFe, yes.
bobwojo sspence9 hours ago

If you are worried about the danger of Lithium Ion batteries you might take a look at LiFePo4 cells, they are much safer.

MFXPYRO sspence10 hours ago

So theoretical then? Have you measured it? Graph of output vs. windspeed.?

sspence (author)  MFXPYRO10 hours ago

Theoretical? No, observed. 42 amps (24v) at 30mph.

JohnT12 sspence4 months ago

Thanks for such a quick answer. I also assume the power of the magnets play a factor. I'll have to look in to NiFe batteries. Sounds interesting. I love this stuff.

John kb8uhn

hawks88 JohnT123 months ago

NiFe batteries are pretty outdated. I had to do a quick google search because in this industry, you never know, old tech could make a resurgence, but I didn't see anything. They're basically the armored tank of the battery industry. You can abuse them and they'll last a long time, but they're not that cheap, they have half the energy density of lead acid, and they have issues with holding a charge.

sspence (author)  hawks883 months ago

NiFe batteries have witnessed a recent resurgence with companies like Iron Edison and Be Utility Free producing improved pocket plate versions that are more efficient (75%), and don't self discharge as quickly. They are the the cadillac of batteries because it's almost impossible to kill them, and they can last 50-100 years or more.

rhkramer9 hours ago

Are you actually getting 1000 watts out of this? At what wind speed?

sspence (author)  rhkramer9 hours ago
Yes, at 30 mph.
I know that programming water jets to cut a out a particular pattern cost quite a bit and so I was wondering if  you would sell the precut disc to those of us who would like to build their own wind turbine. I believe if you were to sell the precut disc, they would help offset the initial cost of programming that you incurred. I can cut them out, but to get the correct balance would take some time that could be better spent on wire winding. Thank you for the information that you have posted and I hope that you might consider this.

check BigBlueSaw.com, but you are correct the unit cost for 1 is still higher than the unit cost for several.

I don't know where you are located but personally water jet and laser cutting is cheaper than you probably think. If you are cutting steel, laser cutting is better. Most laser cutters order raw steel in such high volume that it is usually much cheaper to order the laser cut part directly than to order the steel and cut it yourself.

MFXPYRO AdamR110 hours ago

Plasma cutting may be even cheaper, I get it done for £15/hour and an hour can get you a lot of cutting.

sspence (author)  HariKarier11 1 month ago
I don't have access to a water jet any more. You may want to look around locally.
flagstone7810 hours ago

1000 watts is quite a claim. Could you explain how you got that number?

sspence (author)  flagstone7810 hours ago
ammeter. 42+ amps (24v) at 30 mph wind. of course, that just confirmed the science was correct on the number of coil turns, the awg of the wire, and the length of the blades (swept area). The claim is conservative. Is there a reason you find it noteworthy?
Nutsy11 hours ago
Good instructable.

Any thought to a vertical windmill design for this? They are quicker to adjust changes in wind direction, unlike horizontal windmills, which need to turn.

I don't see a restriction in this, but just wondered if there might be.

Thank you
sspence (author)  Nutsy11 hours ago
I dislike VAWT's as they require too much material for the size, and are always running in drag mode. They are very poor performers. This alternator does not care however. It works with wind, hydro, even engine power.
Hey, saw the small convo on NiFe batteries and I wanna tell you something grand. Apparently there is an aluminum-ion battery in development now. It will take a few years to catch on, I am sure, but I think what they represent is a reserve center in tank-like batteries, with lower production costs, longer charge lives, smaller size, and extreme charging/discharging capabilities, as well as being extremely stable (ie, no li-po puncture fires). They work already, but they only output 2V or so per cell, so there is still work to do in finding a better anode material so that the voltage output increases to something a little more usable, like the more standard 3.7 volts from current lithium batteries. Though they could use them as they are now in 6S to make a perfectly viable 12V alternative. Imagine a car battery, that if it were dead, you could charge it in only 2 minutes. (Given if you have the amperage for that kinda charging)
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