Introduction: DIY 400 Watt Wind Turbine

Picture of DIY 400 Watt Wind Turbine

These plans detail how I built a wind turbine in my garage without any special tools for just over $200. Many of the do-it-yourself designs are either toy projects or unlikely to hold up in strong winds. This wind turbine will withstand 40+ mile per hour winds and produce electricity with as little as 15 mile per hour winds.

I started out with one of those aforementioned toy projects, but soon realized that this design would not stand up to the high winds in central Iowa. After months of trial and error I finally have a design that is strong and effectively produces usable electricity.

I would just like to note that I am a high school senior with no prior experience with electrical systems; so before you tell yourself that building a wind turbine is out of your realm, trust me, it isn't as hard as it sounds and anyone who puts their mind to it can do it.

Step 1: Materials

Picture of Materials

Note: I would recommend getting galvanized steel for all parts that will be above ground. Regular black steel will rust within a couple of months unless you paint it often.

The above picture is a spreadsheet of all the parts I used while building the wind turbine itself.

Step 2: The Generator

Picture of The Generator

The generator is the heart of your wind turbine project and it is important to get a good one. What you want to look for is an industrial DC permanent magnet motor. I got mine on eBay for around $65, and it came with a drilled hub meant for attaching wind turbine blades which saved me a bunch of time trying to make one myself.

My motor is rated for 90v DC at 1750 RPM. Using it as a generator, it will do just the opposite, with 80% efficiency. So if I were to spin this motor at 1750 RPM it would produce 72 volts of electricity. Now, I obviously will not be spinning this motor at 1750 RPM, but you get the concept. In order to charge my batteries which are 12 volt deep cycle marine batteries, the generator needs to be producing at least 12 volts. If you do the math, then I would need to spin the motor at a minimum of 233 RPM to charge my batteries.

With my PVC blades, a steady 15 MPH wind will easily spin this turbine at 233+ RPM, allowing my batteries to be charged.

Step 3: The Blades

Picture of The Blades

Rather than spending hundreds of dollars on blades for my wind turbine, I made my own blades out of scrap PVC I had lying around. Everyone out there tells you to use 8" PVC for wind turbine blades, and let me tell you, it works far better than the 6" I was able to get. I had to get creative to make the 6" PVC work (less curvature than 8").

I started by cutting down my PVC pipe. The rectangles I made are 5.5" by 24". I then cut these down to triangles where the short end is 1.25" wide. After that, I cut out a triangle on the end where it will attach to the generator hub. I clamped the blades in a vice when I cut this and drilled the holes so they would all be about the same.

Tips:

Use scrap 90 degree angle iron when marking to cut; you will get a straight line that way.

You can use a hacksaw, but I would recommend a reciprocating saw.

Use saw blades meant for steel (fine tooth).

Step 4: Blades, Continued

Picture of Blades, Continued

In order to make the 6" PVC work, I added to the design. As illustrated in the pictures, I used steel garden edging stakes with holes drilled in them to add to the length of my blades. The most important part of this though, is the fact that I bent the stakes so the blades are sitting at about a 30-45 degree angle to the hub, allowing the wind to push them sideways and around rather than back, putting less strain on the guy wires and foundation, and producing more electricity.

Step 5: Adding the Wind Vane

Picture of Adding the Wind Vane

Before you get started with this step, I would recommend painting the 48" square tube; mine was not galvanized and it rusted within a few months, so I had to take it all apart again to sand and paint it.

Mark a line down the center of the 1" square tube and cut a slit from one end of the tube a foot long.

The piece of sheet steel will slide into this slit. Drill two holes through the tube and sheet steel, and bolt it all together.

Step 6: Attaching the Generator

Picture of Attaching the Generator

First you want to drill the hole for your power cord. Set your motor on top of the square tube (the motor should be flush with the end of the pipe). Drill a hole where the power cord lines up; I would recommend an oversized hole to make sure the metal does not slice into the cord.

You will next attach the 1.25" floor flange to the square tube. The flange should be just behind where the motor sits (it should be pretty close to being the balance point of the tube). Drill two holes and bolt it on.

Drill a third hole in the center of the flange for the cord to go down the pole. Thread the cord coming off of the motor through both of the holes you drilled and attach the motor to the pipe using large hose clamps (make sure they are very tight).

Note: my motor had a plug on the end of the cord when I first got it, but I removed this in order to thread it through the pipe.

Once all this is done, you will thread a 1.25" diameter pipe nipple onto the flange. I used one that is 24" long, but you would be fine with 18" or maybe even 12". This will slide down over your main pole which is 1" diameter.

Step 7: Foundation

Picture of Foundation

In my experience, a frame staked down resting flat against the ground is not sufficient in high winds, and will allow the wind turbine to tip over, damaging it and snapping the blades. In order to withstand high winds without problem, I dug a foundation and filled it with dirt and concrete in some key places.

I basically threaded together steel pipe, and dug a hole for it to fit down in.

I poured cement around all five of the vertical pipes, and put dirt over and around the rest. There may be more efficient ways of doing a foundation for this, but I just didn't want to take any more chances.

Once it is all in the ground, there will be a male fitting sticking not very far out of the ground. The main pole of the turbine also has a male fitting, so I put a 1" female tee in between the two. This serves a dual purpose as it also is where the cord that runs from the generator down the pole comes out.

Note: The cord that I strung up the pole is just an old extension cord with the male end cut off.

Step 8: Guy Wires

Picture of Guy Wires

For guy wires, I initially used high strength paracord, but they snapped in high winds, so I transitioned to using heavy duty dog leashes made from braided steel cable that came with very sturdy screw-in stakes. I attached them to the main pole using two grounding clamps. The clamps came with bolts and I replaced these bolts with I-screws that the guy wires could easily clip on to.

Step 9: Charging Batteries

Picture of Charging Batteries

I have two deep cycle marine batteries wired in parallel which I charge using my wind turbine. You could easily just hook the batteries up to the positive and negative of the generator with a diode to make sure the electricity does not flow from the batteries to the generator, spinning it like a fan, but I have opted for a charge controller. I got mine from Missouri Wind and Solar (www.mwands.com), and it was made right here in the USA. This has been a very trouble free solution for my application (I don't have to check it often since it regulates charging automatically).

When you purchase a charge controller from Missouri Wind, they recommend you purchase a dump load resistor with it. The charge controller will divert the electricity from the generator to the resistor when the batteries are full, making sure the wind turbine is always under load, preventing it from spinning out of control. I have never found the dump load resistor to be necessary, seeing as I have never completely filled my batteries (they are almost always under load).

If my electrical box looks like a mess of wires to you, don't worry, because if you plan on doing the same sort of setup that I have done, Missouri Wind sends wiring diagrams when you purchase a charge controller from them.

Comments

MusicalBox (author)2016-01-02

Very nice instructable. And I'd love to build one for myself.
I have a dumb question though...
Is the power available all the time ?
I mean do you have to wait for the batteries to be charged to use the electricity or you can use it while they are charging?

You can use it while it's charging.

SamS27 (author)2016-04-29

For slower wind yiu could increase the blade size and use gears to increase rpm. Then you could get higher voltage. Or is my logic faulty?

bobthemoron (author)2015-07-21

Need low wind speed devices to sustain 'off the grid' life style. 15 mph is faster than most sustained winds anywhere in the U.S.

try to attach to a 15 sqm Solar Updraft Tower...

Dr.Bill (author)bobthemoron2015-12-06

Except Hawai'i.

suiterelliot (author)bobthemoron2015-07-21

Unfortunately, this turbine isn't really big enough to get you completely off the grid anyways. With the wind I get, it is helpful in reducing the amount of power I need from the grid.

HiteshD4 (author)2016-01-06

what is the minimum voltage and current produced from 14 mph wind speef

Dr.Bill (author)2015-12-06

This is most definitely good for a camper though.

Noah Czerwinski (author)2015-05-31

What's the wind speed normally where you live and is it 400 watts and hour? Thxs

I would say I average about 15 mph wind. It would be 400 watt hours if the wind stays at about 30 mph for an hour.

jrserra75 (author)2015-06-07

How do the DC motors hold up to getting wet from rain?

I have started putting together a wind turbine but I'm planning on enclosing the motor in PVC pipe.

Once I get my first one done I plan to do an instructable on the second build.

suiterelliot (author)jrserra752015-06-21

Mine has held up fine in all weather the last two years. The PVC pipe around the motor is something I always intended to add but never really got around to it.

badsaddamdotnet. (author)2014-12-28

how many volts/amps are you getting on a regular basis?

In winds of 30+ miles an hour I produce around 400 watts (18 amps and 22 volts) I measure this with my multimeter directly on the leads of the generator.

warpspeed (author)2014-10-26

Wouldn't it make sense to put in a plastic bushing to cover the metal so as to prevent abrasion of the electric cord?

suiterelliot (author)warpspeed2014-10-26

Yes. You could certainly do that. I just wrapped the cord in multiple layers of plastic tape in possible points of abrasion. Seeing as the cord is not rubbing or moving next to metal pieces, though this would really not be necessary.

Vettel (author)2014-10-24

can you give an idea of Current and Voltage you get on a typical mid-wind day?

orphed (author)2014-10-19

No offense but i think the choice of a DC motor is not the best for such application.

It's clearly easier, but will requier some maintain operation in the futur to change the coal brushes.

A brushless synchronous motor would be more appropriated. Electronic is not so big to transform it into an alternator. (only 6 diodes and a capacitor) .

On the opposite, working with Asynchronous as an hypersynchronous generator would be a real chalenge!

Alphageek63 (author)orphed2014-10-20

Hey great idea, but instead of telling this bright and enterprising lad what he should have done, why don't you actually do it and post YOUR Instructible? And spend some time proofreading your posts before turning them loose.

orphed (author)Alphageek632014-10-20

ok, as you wish.
Project is really interesting but I was just informing that for a long term using, choosen technology has it's limit.
I did not wanted to be snobby or so. If you think i'm wrong free to you.

dedehai (author)orphed2014-10-21

Just a few more notes on 3-Phase rectifying:

If your output voltage is low (like 5 volts or so) using diodes eats up a lot of power. Diodes have a forward drop voltage, meaning they eat up some of the voltage (less than 0.6V on your usual Schottky diode, which is what you want to use). On a 5V output that is more than 10% loss, on 12V it is still 5%. That can be overcome by using an active rectifier using transistors (MOSFETs). It is however much much more complex but not that hard to do if you know some programming and electronics. If I had to do this, I would just take a common brushless controller with an available schematic and reprogram the microcontroller to make it a very flexible generator that could even track and adjust to the maximum power point (the motor speed that produces the most power for the current wind situation, see 'maximum power point tracking' or 'mppt').

M2aestro (author)orphed2014-10-20

Yes, the brushless d.c. choice would tend to be better, and a diode bridge would be simple to build; I used many of them in servo applications on gas-lubricated shaft bearings and on leadscrew type drives, and can vouch for their performance with little maintenance. However, consider that the relative costs do not favor brushless d.c. initially, so if you are willing to perform preventative maintenance, i.e. hew to a brush changing schedule, on a brush-commutated generator, you could be ahead. Also consider surplus alternators with diode bridges (some come with those to give d.c. low ripple output). Many ways to change shaft power to d.c. charging power!

lr10cent (author)M2aestro2014-10-20

The problem with many (or all?)alternators is that they need a bit of current to make them work, don't they? Unless they have magnets. I learned this the hard way once, when I got my car started by rolling down a hill, but didn't have enough voltage to get the alternator working. I didn't get very far! They're still a good source of diode bridges, I'm sure. Come to think of it, if they need current to work, don't you have to have brushes to get power in and out of the moving part???

M2aestro (author)lr10cent2014-10-20

If you don't discharge your batteries too deeply (think the failed car battery problem and failed coasting start, which doubly fails when you have the typical automatic tranny setup), you should have current for your alternator in a decent circuit design.

lr10cent (author)M2aestro2014-10-21

Yes, but I read someplace, I think Mr. Piggot's web site, that an alternator may need 40 watts of power. A big price to pay if the wind is light and you'll only make 100 in the first place!

I did have enough voltage to run the car's ignition and even, after a fashion, the headlights. At least until the battery ran down a few minutes later. The coasting start actually worked.

DDW_OR (author)orphed2014-10-19

i know 4 of the diodes are used to make a bridge rectifyer, but what are the remaining 2 diodes used for?

dedehai (author)DDW_OR2014-10-19

Brushless motors generate a three-phase alternating current not just your usual AC. To convert this to DC you need six diodes.

See wikipedia for details: http://en.wikipedia.org/wiki/Rectifier

M2aestro (author)dedehai2014-10-20

I built several systems that had two phase brushless d.c. motors; they can exhibit more ripple without compensating commutation and appropriate windings profile. You can find all sorts of polyphase brushless motors out there, and just match the bridge design to what you have. You also might be able to find a lower speed motor that has a better matched volts/speed or torque characteristic. What you want may not be exactly the motor shown here. BTW, dumping excess energy into a resistor generates some heat, so look at where that heat is going, for safety considerations.

lr10cent (author)DDW_OR2014-10-20

check out the circuit for this 3 phase, full wave rectifier:

http://hackedgadgets.com/wp-content/uploads/2010/1...

That ought to explain why 6 diodes are needed. I was going to figure it out myself, but I got lazy.

lr10cent (author)lr10cent2014-10-20

P.S. If I'd been SMART and lazy, I could have just used the link that dedehai posted. But I didn't notice it.

lr10cent (author)2014-10-19

Nice project! Very enterprising of you. I think using the cable from a dog run for bracing is an excellent idea.

If you make another one of these, you might try a simpler foundation. You could dig a deep hole with a post hole digger, put in some Sonotube, arrange the mounting pole for the turbine within the Sonotube, and pour concrete to hold it in place.

If you're going to be using this thing for a while, you might consider carving some wood blades* or making some with hot wired foam cores with fiberglass and epoxy over. In either case using "helical" pitch.A hot wire foam core would have to be twisted for the pitch before doing the composite part. A wood prop blade could just have the twist carved in. I bet you'd get much higher performance. Probably wood is the easiest, using a laminated blank and perhaps a drawknife and spoke shave. I'd bet the performance would be MUCH better. Also, a wood or properly made composite blade will take a lot more wind to make it fail, fly off, and hit something. Relative to wood or composites, PVC is heavy, weak, and floppy. I'm guessing that your motor could handle larger blades, too, which might increase the output. At least if the shaft is strong enough.

I don't remember where I saw it, but there's a simple linkage you can make so that as the wind gets above a certain point, the tail swings closer and closer to parallel with the disc of the blades, thus easing some of the pressure.

Of course, if you're running off to college, it might not make a lot of sense to do something like this.

I wish I had room for something like this, but I'd have to put it very high to get around all these trees, and I'm not sure the neighbors would want to look at it.

*Look for information about carving propellers for homebuilt airplanes or even model airplanes. (Just remember that a model airplane prop meant for rubber power won't be strong enough unless you use harder wood.). Remember that a turbine blade has the convex side on the back.

M2aestro (author)lr10cent2014-10-20

Nice to post the materials about prop's. Had made wooden prop's but about 60+ years ago. Also, good reminder about the prop profile for turbine being reversed from airplane prop profile. All should remember to check with local building codes for such projects...'twould be a shame to need to take down a well-built project because it was non-conforming! Many local codes require reviews and permits for such a device.

M2aestro (author)M2aestro2014-10-21

Somebody asked "...but what kind of props?..." I carved props for the two stroke gasoline motors common in the 1950s medium size hobby fliers. If it were today, and I needed to put the props on something like this, I'd want to have the assembly dynamically balanced. I've seen the hardware for rent, have borrowed it the past and done it myself for two planes balance, and had production jobs done by a professional shop. With a soundly designed hub, index marks, and a balance disk on the rear of the motor, there would be no reason to have vibration problems adding to the myriad other difficulties that one can encounter with rotating machinery. Enough comments on my part; I have other things to do with my days.

lr10cent (author)M2aestro2014-10-21

What kind of props? Full scale? I've only made them for models so far. A bunch of rubber power props and one teensy one to use with a small electric motor on an indoor RC model.

Speaking of wood for blades, ANC-18 has a whole bunch of interesting stuff to say about wood for airplanes. Many kinds of wood are fine if used appropriately. One place to find ANC-18:

http://www.westcoastpiet.com/construction.htm

I'm sure there's some other FAA publication about wood for propellers.

I suspect fir stair tread material might make nice wood for turbine blades.

suiterelliot (author)lr10cent2014-10-19

Thanks for the input! I looked at carving my own blades, but opted to make PVC blades because of cost and simplicity. I really wanted this to be a project to get other people interested in wind energy and it's just my first attempt, so I tried to stick with the basics.

lr10cent (author)suiterelliot2014-10-19

I can understand that. It's just that the rest of your project, I think, deserves a better prop and could put out a lot more power. Still, you're probably moving on to other things, right?
------------
How much did you pay for the PVC? I wouldn't be surprised if it turned out that wood was cheaper. Particularly if you can scrounge, or with the right kind of saw, you could make thin strips out of a couple of two by fours and use that. (Carefully selected to skip the knots, of course.) You could probably glue up the boards with Titebond 3, Weldwood or, if you can find some, resorcinol. You could just carve directly from a two by four if you had one that wouldn't warp. I'd say use plywood, but I'm not sure how well you can carve the cross grain.

If you had a nice hand plane, you could probably smooth out some slats taken from broken pallets, as long as the grain was good and straight.
------------
Please forgive me for all this vicarious speculation.

M2aestro (author)lr10cent2014-10-20

They still make Weldwood?...haven't used it in about 50 years.

random squigles (author)lr10cent2014-10-19

Hugh
Piggott of Scoraig Wind Electric sells nice plans for carving your own blades from wood. He has been at it for decades.

jerry.firebaugh (author)2014-10-19

Attaching the blades to the flange that is directly attached to the shaft of the motor imparts a longitudinal thrust to the shaft. The wind, in pushing on the blades, pushes the shaft towards the back of the motor. The bearings in a DC motor or designed for rotation only. They are not tapered or angled like a vehicle's wheel bearings. The thrust of the air pushing the blades backwards will wear out the bearings very quickly. This type of motor would be better suitable for for a VAWT (vertical axis wind turbine) design. VAWT turbines don't put as much thrust force on the shaft.

M2aestro (author)jerry.firebaugh2014-10-20

We (in my old business days) swapped out many deep groove bearings for angled contact bearings, and there are many drop-in replacements in various angles of contact (some optimized for thrust) that have about the same depth and have the same diameters as the shaft bearings usually found on d.c. motors and alternators. On the angular contact bearings consider orienting them such that the vectors of contact face outward, away from the motor's center. Also, do not limit them too tightly, such that differential growth between rotor and stator becomes a preload problem. That would be one reason for the kind of bearings that are normally installed on these motors. One should be very careful how one presses the old bearing out and presses the new one in to avoid damage to the races and motor housing. Seek guidance on what fits your individual case with respect to the motor and bearing choice.

seamster (author)2014-10-17

Excellent project, thanks for sharing this!

frash (author)seamster2014-10-19

Your 400-Watt Wind Turbine is quite impressive, particularly the blades from 6-in PVC pipe rather than 8-in PVC pipe.

Some prop blades for small, simple model planes are made from cylinders or tapered cylinders such as buckets or cones. Your structural constraints are much more important but some of the design methods may be similar. Fitting the prop blade constraints used the Excel Add-In "Solver". See http://www.hippocketaeronautics.com/hpa_plans/cate... (Bucket Props)

frash

lr10cent (author)frash2014-10-20

That spread sheet makes it easier, but I think that the blades he's already made use this principle, as the cuts don't appear to be straight up and down the pipe.

lr10cent (author)lr10cent2014-10-20

Just had an idea. If stronger or stiffer blades were needed, one could just wax the existing PVC blade and lay up some fiberglass over it. Using polyester resin would make this go very quickly (and stinky!). I'll have to remember that if I ever want quick and dirty turbine blades, but I probably don't have a place for such a project. If I did do it, I might go to the local fiberglass guy and see if he'd sell me some of the tow that they use in chopper guns. The other materials could come from the local auto body supply or car parts place. With all the fibers straight, it's much stiffer and stronger than cloth, though it would have to be in two or three different directions unless some cloth was used with it. An alternative, inexpensive mold would be Sonotube or other cardboard tubing used for pouring concrete. This can be had in 8 inch diameters and up. A 4 foot piece is pretty cheap.

GollyRojer (author)2014-10-19

Congratulations! Nice project, and good job documenting it. One question regarding the steel tube vane: was there a reason not to use PVC for this? I would have thought of it first, probably 1 1/2" with a trough cut where the motor straps on.

M2aestro (author)GollyRojer2014-10-20

Remember always, with projects like this, that safety is paramount in rotating machinery. Remember, too, or learn it now, that the highest stress in the system described is at the hub. You don't even want to think about using a pvc hub of scavenged materials, I'd say, nor would you, if you don't have the tools for analysis, want to wasted the time attempting to design one. Flying prop blades or pieces of them, as a result of hub failure could lead to tragic results! I have not yet looked in detail at the blade - hub attachment, but this is a place that you want to focus real attention and careful construction.

suiterelliot (author)GollyRojer2014-10-19

You could probably to this, but I would be worried about the strength of PVC with such a small diameter.

lr10cent (author)suiterelliot2014-10-20

You're right. PVC would also be much floppier. Elastic modulus of steel is around 30,000kpsi, and even the worst steel has a yield strength of 30kpsi, though it's usually a lot higher. Elastic modulus of PVC is around 500kpsi, or 1/60 that of steel. Yield strength of PVC is on the order of 4 to 9 kpsi.

decc1954 (author)2014-10-19

Must have been a typo?

Missouri Wind and Solar website, charge controllers, is:

http://store.mwands.com/charge-controllers/

Can you update us with the specific charge controller?

We have a solar panel array at our off grid cottage, at the top of a hill.

This would be great for those cloudy weeks.

I am a strong believer in charge controllers, since we have access to our cottage only intermittently.

Thanks so much for a great instructable!

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