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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

Picture of 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

Picture of 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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@dennisS4

I don't get your point. This is a great place to share ideas.

sspence (author)  AndyB22 days ago
I think he is confused, because I'm not selling anything. Additional details are available on our discussion group, not just my project, but those of others doing the same type of projects. That's free too.
carlhoffman sspence47 minutes ago
This whole thread is useless. This isn't Facebook. If you have a complaint about a user's instructable, email the support team for Instructables, they're great at resolving issues. There's no need to go on the offensive and berate the author. And I'll say it again, this isn't Facebook. If you don't like the author's post, move on, there are plenty more to be had on this site.
DennisS4 AndyB219 hours ago
Thank you for your reply :)
sspence (author)  DennisS42 days ago

You don't have to buy anything. all the details are free. I'm not selling anything.

DennisS4 sspence19 hours ago
I concede. Your right as I said. It's a wonderful how to and I hope it helps many people. Best of luck to you.
Ok, first off your right. I didn't go through the sign up process at Y!
However you are wrong about selling the plans, along with the sign up you have a ad saying sign up for X magazine and get two plans for your project free. I stopped when I saw that. If you really wanted to share your project you should have posted the complete project and not require people to join your group to get more details. I stand by my original post, this project is an advertisement to join your group or by magazines. With that said I'm glad that this is a popular topic and you have given more information in the comments.
sspence (author)  FlorinJ2 days ago

Florin, That's your prerogative. I don't care, I don't make anything off this. It's here for those that appreciate it. The goal was to show what is possible, to those that may have not thought about making their own power. Many more details are available on the yahoo group, along with years of correspondence between other makers. It's a free group, it's not "restricted" in that you have to pay to use it, you just have to click join. That helps keeps the spammers away.

sspence (author)  FlorinJyesterday

Restricted in yahoo speak means you have to ask to be a member. If you don't want to join to read other members submissions, you can find another group. I can't take other members information and load it on another site. It's your opinion this instructable is "ad like", but since there is no ads, that's just your opinion. DennisS4 is the one who claimed "advertisement to buy the DIY document". He apparently can't read. Maybe insdtructables puts ads in, I don't know, I don't see them as I run an ad blocker.

AndyB23 days ago

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

sspence (author)  AndyB23 days ago
I'd like to know how many actually went out and built one :-)

Dennis,

While I understand that upon first seeing the Yahoo group "Restricted" designation, you may think that you would have to pay, etc, but before actually going through the process of logging into Yahoo groups, then trying to join the group, please keep in mind that complaining in the comments that you have to pay, or go through some complicated process to get the info, to a lesser level - MANY groups on the Yahoo site, and others ask that you click the join button, and a group admin manually adds you to keep the thousands of bot-created ads down in the posts. This has been the case since the mid-90's with BBS forums, etc as well. Nothing new here..

On a side note to everyone else...

I agree that the PDF's, and "full" information should be shared on this site, and that it is against the spirit of the site for the author to say they are only using this as an instructable for what is possible, instead of how to actually do it. I believe this is more of an ad for "Come join our Yahoo Group so we have more views!" than anything else, as even basic safety info is left out. It's concerning that someone might try to put one of these together after seeing the wait-wall in the group application process, and hurt themselves.. Much more care should have gone into the info actually shared, vs the baiting to join a forum..

sspence, please clear up the confusion and take your instructions/posts/etc regarding this turbine that you have in the Yahoo group, and post them as attachments here on this site, and link to your group for questions, other learning, etc..

Hey dude,

Feel free to post your instruction in here too. There is absolutely no fee and people are burning for your great ideas

sspence (author)  DennisS42 days ago

There is no subscription fee, and the group is free. there's a lot more storage for files there, and many group members have posted their instructions as well.

rsteadman110 hours ago

I have a question. First off, I really love what you're doing with the whole "Off the grid" thing, power to you! (Pun!) But my question is how much AC out is that thing giving off? and if it is greater that 120V ac, is there a way to make it single phase, and regulate it? Thank you so much for you time, and this fantastic Instructable!

sspence (author)  rsteadman19 hours ago
We build these in 12, 24, and 48v versions. 120vac is produced by the inverter.

I wanted to see the details of the axial-flux alternator design, as I have built these for the military. The unusual thing I note in your instructable is the slots in the steel disks for the magnets. If the magnets are magnetized through their thickness, as required for axial flux, the discs should have no slots, and the magnets placed directly on them, so the back-flux is carried through to the next magnet. A separate plate made of non-magnetic material should be used to secure the magnets in place. (This appears to be the way you made it in the references). This increases the flux density on the inside of the alternator. The steel backplate should be half as thick as the magnets are "wide" (dimension in the circumferential direction). If an iron object is attracted to the backplate, then it is not thick enough.

No water jet is needed. The magnet spacer plates can be aluminum, which is easy to cut with hand tools. The steel would be a uniform thickness circular plate with a mounting hole in the center.

This type of alternator design is optimum for high speeds. It would work best if you geared up the turbine to the alternator. For the slow speeds of the turbine, a car alternator with the rotor replaced with magnets would work better, but care is needed to keep cogging torque low. Cogging torque can be reduced by either skewing the magnets, or mounting them slightly "off" the 12 evenly spaced configuration.

To get efficiency under varying winds, you need a "maximum power point tracking" DC/DC converter system, because the power available from the wind varies as the cube of the speed, and windmill speed should be roughly proportional to the wind speed, but you are connected to a fixed voltage, forcing the windmill to be overloaded at high wind speeds, and underloaded at low wind speeds.

You should mention the safety hazard of assembling such a large array of magnets together. The force between the 2 disks could be over 500 pounds!

sspence (author)  bpark1000yesterday
The steel plates are not slotted, they are solid. there is no detectable magnetism on the back side of the plate. Because this is an air coil, there is no cogging. Gearing would just rob power, and is not needed in this 650 rpm design. The alternator produces max power at 650 rpm. Higher speeds complicate the design.
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.
www.mcmastercarr.com or maybe it is www.mcmaster.com
Either way they sell pre cut steel discs.

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.

www.mcmaster.com they sell precut steel discs
MFXPYRO AdamR13 days ago

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

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

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

OK I'm interested to make a wind generator as living in the Highlands there's almost always a wind, and sadly as I don't own any shoreline I can't do a wave generator (IMHO much better).
But I'd like to make the wind 'propeller' from a 'wheel', like the fans that are used for vehicle fans. Now I've wondered if I took this type of technology from the above system, but place loads of these little fans at the edge of my rectangular shaped property then at least one face ought to be running. Plus it's no higher than the property and subtle too! I reckon the noise factor too would be reduced.
But there's another reason too ... we often get extremely high winds. Ariel photographers I know often record 139mph. So most wind generators will get blown over ... The one of the Faroe Islands took 3 before it stayed up!
So if the little ones (6" diameter or so) are going too fast I thought that I could have a cover that could shield them, or open them for direction or folded away. :)
What are your thoughts please ? I am not technical (as you have guessed already I'm sure!), but good at DIY and mechanical & basic electrical projects. :)

zachschi2 days ago

Wow great build, any ideas on approximate cost? Where do you think the best place to source magnets and magnet wire is?

sspence (author)  zachschi2 days ago
It was $500 (not including tower) when we built this one, it's closer to $1000 now. These guys used to sell parts, I'd contact them to see who they recommend. http://otherpower.com/online-store
sb42 days ago

Great instructable. How did you learn to make this design, do you have background of some kind? Now I'm wondering about the efficiency. Looking at motor designs, the magnets and coils seem much more closely integrated, I'm guessing has something to do with making sure the wires fully cross the magnetic field lines or something like that. Your design seems more "loose". Is there any optimization thought put into it, such as how many windings in the coil, the gauge of the wire, the interaction of the magnets with the coils, etc? Also the aerodynamics of the windmill, do you know the efficiency? (Bottom line is that 1000 watts is very impressive to me, just curious.). Thanks.

sspence (author)  sb42 days ago
It's all about the interaction between the number of windings, the wire diameter, the strength of the magnets, etc. All these parameters were chosen carefully. Some efficiency is given up to make it a backyard buildable design. My background is electronics, but I learned this design from the inventor, Hugh Piggott, another backyard wind builder, Jim Juczak, and The two Dans, Dan Bartmann and Dan Fink, who have taken this design and really developed it into an art form.
Tenire3 days 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)  Tenire3 days 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.
I think either you or I misinterpreted the wisdom. The spiral blade portion refers to using something like a furnace blower fan so it doesn't have to rotate. Would using something like that reduce the power output?
sspence (author)  Tenire3 days ago
to reduce coil size, enameled solid copper is traditionally used for motor and alternator windings.
ggallen1032 days ago

My take on what is the difference between a prop and turbine - with a prop you need the most efficient usage - because the last thing you want to do is get out and push!

lr10cent3 days 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)  lr10cent3 days 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?
sspence (author)  Dillon020032 days ago

30 mph winds will drive this at 650 rpm at full load.

You can figure a rough "guestimate" of what rpm might result form any given wind speed... that assumes no load slowing the prop/fan/turbine

(Pitch is the distance forward the prop is angled to "move forward" per revolution)

Pitch (inches) * rpm = inches /min.

Conversion factors needed assuming wind speed is mph.
* 60 min/hr = inches / hr
* 1 ft / 12 inches = ft / hr
* 1 mile/ 5280 ft = miles/hr

You calculate the pitch needed for the desired rpm at any given wind speed by inserting numbers into the equation

X * 650 rpm = wind speed

Variable pitch is the only way to have the prop/turbine "want" to spin a fixed rpm with variable wind speed. The classic farm windmills used a method to change the angle of the flat paddle blades. Actually a very simple solution to the problem. Those windmills pumped a lot of water....

( http://aermotorwindmill.com/ logo is the classic farm windmill )

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