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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This seems more complicated than it needs to be. Couldn't you just make a large fan assembly with large pulley tied to a small pulley on a car alternator to charge a bank of deep cycle marine batteries with an inverter? Maybe add a controller to it to protect the batteries from overcharging? I use something similar to power my camper going down the road.

sspence (author)  mike.johnston.3367yesterday
No, wind doesn't work well with car alternators. Too much loss in the alternator, and the gearing. Close to 75% of your power being thrown away.

I have a fan connected straight to the front of a small alternator going to 2 deep cycle marine batteries mounted to the top of my great. no gearing spins in as little as 5 mph wind speed.

sspence (author)  mike.johnston.336710 hours ago

We aren't try to spin blades, we are trying to produce serious power. A car alternator is designed top spin at several thousand rpm, and is only about 60% efficient. You built a toy, not a power generator.

Whatever, it works and didn't take long or as much $ as you spent to make. Build a couple more with a few more batteries and I will have the same power output as you with a fraction of the cost with no controllers needed as they are already built into the alternators. So go ahead dumb down this and everyone else's idea on here like I have been reading....spend your are right and we are all wrong.

sspence (author)  mike.johnston.33678 hours ago

Yes, you are correct. I am right. Engineers tend to be. Car alternators are not designed to charge deep cycle batteries, without replacing the regulators with smart regulators (used in the marine industry for house battery banks). It's a common problem to ignore good advice and chase rabbit holes when you don't understand the technology, or the physics behind it. It's ok, that can be cured with education, which is the point of this instructable. For about $1000 you can produce 1000 watts. You won't come near that with your "solution".

Really? You think alternators are not designed to charge deep cycle batteries? you are the dumbest engineer on the planet. Check out just about every boat on the water genius and you will find 1 regular starter battery and 1 ... wait for it....DEEP cycle battery. My boat actually has 2 deep cycle batteries and 1 starter battery and only 1 alternator to charge all 3 so don't tell me this set up don't work...been working for the boating industry for over 50 years. And yes they are car alternators and not generators. Just because you say you are an engineer doesn't mean your way is the only way to solve a problem or the cheapest way either.

sspence (author)  mike.johnston.33677 hours ago

Apparently you have not heard of 3 stage charging. Your batteries will fail prematurely. Good luck. My expertise is in designing wind and solar power systems for longevity. I get 12+ years on a deep cycle. You definitly won't with your "expertise". Good luck to you.

Never said I was an expert. going on 6 years with my fist set of batteries. I have been baffling Toyota engineers for 20+ years by doing things to their 7MGTE and 4AGE engines that they swore could not be done so I really don't hold a high regard on what an engineer says can or cannot be done just because the "Data" says so. Tell me something, how high of a wind force can your so called wind generator in the picture handle? doesn't seem like alot. Mine being small and robust has handled up to 100 mph tornado forces that came within 1/4 of my land and didn't even scratch the paint. Thats what I call longevity.

sspence (author)  mike.johnston.33676 hours ago

This wind turbine develops full power at around 30mph, and turns out of the wind. It has handled 100+ gusts with ease. If you don't have a physics or engineering background, you can believe all kinds of things that aren't so, but I have the experience to back up my calculations, and my education. Good day sir!

Its like arguing with Sheldon from the Big Bang Theory...he's always throwing around his degree's and education also. Sorry, but if your referring to the wind generator in the pics of this article and trying to convince anyone it can survive 100 mph luck with that. Engineers....all practicality. Good luck with you and hope you survive when SHTF.

sspence (author)  mike.johnston.33673 hours ago

This engineer has 30 years of practical hands on experience. Grew up on a farm doing everything from welding, to plumbing, electrical, and carpentry, as well as mechanics. I've lived off grid and had to live with just the power I produce. Some have hands on experience, but it's accidental, becasue they do not understand the experience (cargo cult). Others have the education to understand what they experience and apply it effectively.

birddseedd9 months 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.

You can get grid tie inverters on ebay for $100-$500. About $250 for a 3k watt which should cover a lot of your power.

Hey mykiscool, can you please show me one. when i looked they were $3500. I need a 10k watt inverter.

sspence (author)  mykiscool3 months ago
They don't work with this wind turbine. Please limit your comments to the topic of the instructable.
mykiscool sspence3 months ago

If grid-tie inverters don't work with this wind turbine, please tell me why. I'm in the process of building this turbine and would like to connect it to my grid-tie inverter. How can I make this turbine compatible.

It does work with grid tie inverters. I don't know why he would think it wouldn't
sspence (author)  birddseedd3 months ago

No, it does not. Why do I think that? Maybe because I'm a wind and solar power designer, installer, and 30+ year electronics veteran. This unit must be used with a battery bank and a diversion load controller.

mykiscool sspence3 months ago

Oh, ok thanks. That clears it up. So it should still work if I connect this to a charge controller and then to batteries and then to an inverter as I'd planned. At first, I thought you meant it won't work at all.

sspence (author)  mykiscool3 months ago

There were a number of posts referring to the inexpensive PV mounted direct to grid inverters. Those will not work. A battery type grid tie inverter (Outback GTFX) will work.

If it works with a load controller, it will work in an inverter. A wind turbine still outputs 12v dc, which can be used by an inverter, or battery charger.

sspence (author)  birddseedd3 months ago

micro grid tie inverters don't typically run on 12vdc. still need a battery to keep wind turbine from self destructing, as micro grid tie inverters turn off when grid goes down, and wind turbine will freewheel without a load.

^^^ what he said

What doesnt work with it?

sspence (author)  birddseedd3 months ago

solar type Grid tie Inverters do not work with this wind turbine. This unit is designed to charge batteries for off grid applications. Some inverters can take battery power and sell back to grid, but not the units that were being discussed which are designed to connect a solar panel directly to line power.

The turbine is just the source, you can do whatever you want with the energy.

sspence (author)  birddseedd3 months ago

You might think that, but this source has particular parameters that need to be met to keep it from self destructing. You might want to take the word from the guy that built it :-)

In michigan i would have to have 10k watt. for a grid tie inverter i cant find one on ebay. if i wanted to go off grid, im still looking at 10 to 15k
sspence (author)  birddseedd9 months 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.
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)  birddseedd9 months 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)  birddseedd9 months 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
sspence (author)  birddseedd8 months ago
This is for tinkerers. you have to be handy, and love to build stuff. you probably won't save money. it's a good back up for a solar power system to keep the batteries charged when the sun isn't shining.
If i had 10 of them. Although i don't have space for 10 of them. unless i line them up on my roof. hmm. how much did this cost to build?
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