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

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

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.


Step 3: Build the bearing assembly

Picture of Build the bearing assembly
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

Step 5: Further Reading

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JohnT121 month 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)  JohnT121 month ago
Ohms law. number of coil turns, wire gauge. rpm. blade length, wind speed.

Not interested in Lithium based batteries. NiFe, yes.
JohnT12 sspence1 month 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 JohnT1211 days 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NiFe batteries are pretty outdated.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)  hawks8811 days 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.

Calderick12 days ago
I am an upstart inventor and id like to get in contact with you regarding the specifics of power generation.
sspence (author)  Calderick12 days ago
ttucker1015 days ago

couldn't you use a car alternator? I'm not being funny.. Wouldn't that work too?

sspence (author)  ttucker1014 days ago
No, it would not. Car alternators have power robbing field coils and are designed to turn at several thousand rpm.
OK thanks

this is all new to me but have been interested in going green for some time. I live in the mountains of North Carolina, so we have wind all the time. I am going camping for an undetermined amount of time. I bought a ten person, 3 room cabin tent so I would not be cramped for space. I have been researching several kinds of windmills and yours really caught my attention. most of the windmills I have looked at won't power much, but yours seems to have the power I need. I need something that will power a dorm frig and a microwave and also charge my laptop and cell phone. I am not really that mechanically inclined, so I will have to have someone help me. is there anyway you can send me step by step instructions and material list?


Robert P.

sspence (author)  horsewhisper604315 days ago
If you need step by step with theory explanations, and a beginners class in electrical generation, I suggest Homebrew wind power
gpoli223 days ago
I'm about to wind the coils and was wandering what lenght u used for the 2 strands of 14 gauge wire?
And how much should the centre spacing be? Or doesn't this affect the coil as long as it has 35 turns?
sspence (author)  gpoli223 days ago
on a 1x2x.5 magnet, each turn is about 7"

Hey, just a quick question I've seen in other designs that all the coils are flush to each other and in this one they are spread out. I was just wondering if you knew if there was a difference between spreading them out like yours or having all the coils touching each other?

sspence (author)  guitarplayr21 month ago
coil size is dependent on magnet size. This is a larger diameter disk, so they don't touch. if the disk was smaller, the power pulses could be a bit smoother. Doesn't matter for battery charging.
puppy_0071 month ago
Hi there ! If i use 20AWG wire and 125 turn with 9 coil star connect .24 magnet 2 rotor at N50 1-1/2 dish . Is that will be good ? Can i get 10-15 amp at 12V with 200-300 rpm . Please thanks
sspence (author)  puppy_0071 month ago
You may very well, depending on wind availability. experiment.
Thanks alot
puppy_0071 month ago
Hi there ! Please tell me how many amps you get at 12v ?
How many rpm at 12v . Thanks in advance !
sspence (author)  puppy_0071 month ago
80+ amps at 650 rpm
Hi ! Thanks for your reply .
Is there any way i can get 12V at 200 or 300 rpm .
I only need 10 or 15 amps at 12V . Thanks
sspence (author)  puppy_0071 month ago

You would have to wind many more turns on the coils to develop voltage at lower rpms. at lower current, you can wind with smaller diameter wire than we used.

sspence (author) 1 month ago
yes, the strength of the magnets also affect power output.
NRG4UandMe2 months ago

Excellent - this is a great share ! Thanks !

birddseedd1 year ago
Ya know. this kinda stuff sounds great, but, it really isnt all that piratical if you live on grid. average it out i spend 100 bucks or so a month. for me to buy a grid tie inverter or a battery bank/inverter/charge controller is going to cost me 3 grand. thats a 100 dollar a month loan, and i don't even have power yet. Even building my own solar panels will still cost me around 8 grand total. Thats over 150 dollar loan. I would be paying more money.

But how long would your loan last? and long will you the power company? No Brainer.... I would rather pay for own for 5 years instead a lifetime for power companies crap

A 25k loan over 5 years is near 500 bucks a month. sure it only lasts for 5 years, but i could invest that 300 dollars a month for 5 years and gain a whole heck of a lot more money than i would ever save in electricity.

then why are you worrying about costs if you clearly know how to make lots of money?

Because right now i have to invest 1500 a month+ into my company. Itl be that way for a couple more years
But after 5 years ALL of that money could be invested or saved. One never knows what the future may hold, if there even is one. I would rather my money be used for me and my family, now or for down the road freedom. What if the near future brings a collapse of our economic system? That money you would be investing will no longer exist and there will be no more power companies to provide power. We should be moving each dwelling towards self sustainability.
sspence (author)  birddseedd1 year ago
So don't live on grid. I spent $20k on my power system (complete), and immediately saved the $30k the power company wanted to extend the lines to my property.
you must live waaaaay out in the boonies, must be nice.

where i live it is 10k a pole. 30k is 3 poles which is merely a stones throw to the grid. This could be a a 3 acre parcel of land which is not much and very common. Birdseed, you should equip yourself with the proper information before you ignorantly speculate against the authors advice. Spence is very highly trained and educated in this exact field. Neither you nor I are, so arguing a reasonable explaination seems rather foolish to me.

I forget, what are we arguing about?

The issue is i don't have to spend any money getting electric to my house. its already there, all i have to do is buy the electricity. so, 100 bucks a month on electricity, or 20 grand on my own power system.
sspence (author)  birddseedd1 year ago
So why are you even bothering to comment on this instructable. This is for offgridders and diy tech heads. I don't comment on knitting instructables and tell them how they should buy their clothes at walmart ......
because i am trying to find someone who can show me an affordable way of doing it. and on grid vs off grid is not really an issue. its going to cost about the same, if not more.
sspence (author)  birddseedd1 year ago
Good luck. It's not about saving money in most cases, it's about independence. being able to build beyond the grid.
I want to save money. just not sure if its worth the 5 year investment till im in my last home
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