DIY Wind Turbine – DC Motor – Generator
Posted on January 12th, 2009 by Bruce
DIY Wind Turbine – DC Motor – Generator
Do-it-yourself small wind turbines are quite simple to make. The biggest key to success is picking the right DC Permanent Magnet Motor.
The basic parts to a small DIY wind turbine include:
- Tower – get your wind turbine up high and into clear wind. The higher the better. Expect a good tower to cost as much to make as the rest of the wind turbine – half of the total cost.
- DC Motor – very important to pick a motor that produces useful power at LOW RPMs. Do not buy a motor that only produces the voltage you need at rates of 1000 RPM or higher. If you look at eBay you will see lots of motors for sale “for wind generators”, that WILL NOT WORK. They often need RPM rates that you will never get from your wind turbine. With a homemade generator, you get useful power at 150-250 RPM. Be very careful on your DC Motor selection.
- Blades – size depends on the motor selected. Larger is not always better. A wind turbine with 2 blades will turn faster than a turbine with 6 blades. A wind turbine with 6 blades has more power to turn a larger motor.
- Vane – points your turbine into the wind.
- Electronics – an inline diode to stop your turbine from draining your batteries when there is no wind. Rectifier or controller to charge the batteries. And a Kill Switch.
- Diversion Load – to consume the extra power produced when the batteries are fully charged.
Though all parts are required for a functioning system, I believe your DC motor will make or brake your project. Make sure you know what you are getting!
May the wind always be in your blades…
Similar Posts:
- Furling – Protect Your DIY Wind Turbine
- DIY Wind Turbine Projects – New York
- Homemade Wind Turbine Very Popular
Filed under: Wind Turbines
damn , I wish I had read your page on which mototr to choose before I bought one.
Keep up the good work trying to help us newbies
Peace
Gav
Hi Gavin,
You have a good looking site – Kernelpower.uk.com.
Yes… it’s a challenge to find a good motor that doesn’t need to be geared.
Here’s a link to a video of one gear setup – seems fairly easy to do. The video is at the middle of the page.
http://www.greenterrafirma.com/DIY_Wind_Turbine.html
I’ve also added some info on how to make your own alternator, that produces power at very low RPMs –
http://www.greenterrafirma.com/axial-flux-alternator.html
Making your own alternator will add a few extra hours of work, but you get a product that will LAST in the rain and produces power with much lower winds – they are worth the effort.
Have fun…..
Bruce.
Can you please help me with picking a motor. What RPM should I have to get per volt
Sam,
You need to get 1 volt output for every 25 RPM or less. Thus, if your wind turbine is rotating at 400RPM, you would get 16 volts out, but you lose 0.7 volts across the diode and a bit more in the wiring. You could end up with 15 volts, which is barely enough to charge a set of batteries.
There are several DC motors listed on ebay, that only produce 1 volt at 50 RPM. These motors would only produce a charging voltage during a windstorm strong enough to damage your wind turbine!
Bruce.
hello bruce i just purchased a leeson 180vdc with 1750 rpms..i hope i made a good choice i did the calculations 1750/180 and i get around 9.7 rpm per volt…which i think is pretty good right? now im just trying to find out if i should use 3 blades for it or 6?..also..i found 2 types of plug-n-play grid tie inverters.. where you basically hook u the turbine to it..and plug it in the wall and your feeding power back to the grid..i read that what i should do put a couple 12 volt car batteries inbetween the turbine and the inverter to act as a buffer..it says this way eleminates the purpose for a controller because now the inverter has a constant source to take juice from…and acts as a buffer basically.what do you think about that and also would i still need a diode?
Bill,
The RPM’s sound good. What amps does it output?
Generally speaking, 3 blades will give you faster RMPs, but 6 blades give more power and lower start-up windspeed. Since you are not gearing up this motor, you likely don’t need the power and would be better off with 3 blades. You can always try it both ways as PVC blades are not expensive.
Inverter – please be aware that in most (all?) locations, it is against the law to just plug in an electrical generator to the domestic grid. Your local electrical supplier needs to know if you plan to put power onto the grid – from a safety perspective, they may shut off the power to work on the lines and your system would still be supplying power! They need to approve your inverter and will likely require a lockable cutoff switch, etc.
Howerver, you can produce power for your own use, if it’s not connected to the grid. For example, you can wire up your own (separate) fuse box and household power plugs – make sure you label any new plugs. Check your local regulations to see if the new plugs must be located a minimum distance from the grid connect plugs, and for outher rules/restrictions.
I can’t comment on the specific inverters you are looking at. Some things to keep in mine – if you add batteries, you will need a controller to manage charging of the batteries and directing surplus power over to a diversion load. Your wind turbine will produce power when the wind blows and unlike solar panels, this power must go somewhere (batteries or a diversion load when batteries are fully charged). If you have a controller, it will replace the diode. If you don’t have a charge controller for the batteries, you’ll need the diode, plus you need to manually manage the charge on the batteries – this is very difficult to do manually. Charge controllers for solar panels can be found for $25 and up. Charge controllers for wind turbines are more complex and will cost you more.
Hope this helps… Bruce.
P.S. Sounds like I need another article on batteries vs grid-tie and one on controllers/inverters.
the motor is a 2.5 amp…the amps didnt sound great to me when i bought it..but everything else on ebay is like 24 volts at 6000 rpms..be lucky to get 12 volts in a hurricane.(but they sellers say they are great for wind turbines)…so the best one i saw was the leeson..plus i saw a recent you tube video of a guy with a 90 volt 1750 rpm leeson..generating 25 volts in about 10 mph winds he has 6 blades here – http://www.youtube.com/watch?v=aMfNQQ77nTM
but the purpose why im doing this is to lower my electric bill..so i want to connect it to the grid.. as for the controller the plan i was thinking the surplus power after the batterys are filled would be fed to the grid..i also read that if i hook up a grid tie inverter straight to a wind turbine it would need to constantly make alot of power…hence putting the batteries in line the inverter then has a steady supply of constant power to draw from to feed to the grid..here is what one site says
With an Islanding grid-tie system, you would simply wind your turbine’s stator for your system voltage (battery bank voltage).
(An islanding grid-tie system is one that uses batteries for back up.)
After your grid-tie system is inspected, permitted, approved and turned on by the power company, you would wire your turbine into the battery bank just like you would do in an off-grid system.
The system would not have a diversion load controller running heating elements, though. Instead, your grid tie inverter gets rid of extra power by selling it to the utility.
UL listing is not generally a problem–there are no UL standards for wind turbines anyway. Only your grid-tie inverter and it’s associated disconnects, wiring, etc. would need to be UL listed.
here is the link..let me know if its bad info thanks!!
http://homebrewwind.com/wordpress/?tag=grid-tie
p.s..here is one of the inverters i was looking at..says sort of the same thing..
http://www.tlgwindpower.com/200watt_gridtie.htm
Bill, if you had a nice steady wind and produced around 440 RPM – your output would be around 30 watts from this motor. I doubt that you’ll produce any surplus that needs to be fed back into the grid.
I suspect that the inverter would turn on whenever the batteries had enough voltage to run it. The inverter would then produce power and feed it into your household wiring. Once the battery voltage dropped below the level needed by the inverter, it would shut off. The wind turbine would then recharge the batteries. The batteries would never over-charge, as this inverter can drain more power, than the wind turbine can add.
As mentioned by homebrewwind.com, your system would need to be inspected and passed before you would be allowed to connect. This will cost a fair penny to do. The inverter also needs to have UL approval for grid-tie – confirm before purchase.
Bottom line – a small system like this makes a nice project, but the cost to connect it to the grid will not be covered by the power produced. In off-grid systems, you don’t have the same rules, regulations and inspections. You may want to keep your system as standalone.
darn…guess the motor i picked wasnt all that well because of the amps…every website i read just tells to look for the voltage and rpms…not amps…i was trying to get a few hundred watts…so i take it the amps need to be higher right?
True, a motor that can support 10 amps would be much better. There are some sites that show you how to make your own alternator. You would need to purchase some good magnets, copper wire and be able to use resin. From what I can see, it also helps to have a welder. A friend of mine owns a welder and I’m thinking of making an alternator as a weekend project come summer. Here is the link to some info we have pulled together. Once we have pictures etc., from building our own, we’ll add to this page.
http://www.greenterrafirma.com/axial-flux-alternator.html
i hear ya..hey i been looking around. and i found i could gear up the motor…what do you think about that? i found this link of a guy that geard up a ametek 38. ill probably do that just a little bit differently as far as his construction of the turbine ..if i do that i will probably have gears instead of the belt..and ill build mine as strong as a brick shit house….think it will work gearing it up?..here is the link
http://www.youtube.com/watch?v=9oI0N21QqwA
Yes Bill, that’s the video we have linked from our web page explaining how to build a wind turbine.
http://www.greenterrafirma.com/DIY_Wind_Turbine.html
We also have a section on permanent magnet and Ametek motors here:
http://www.greenterrafirma.com/permanent-magnet-motors.html
And another on furling to protect your wind turbine:
http://www.greenterrafirma.com/wind-turbine-furling.html
And more on VAWTs….
http://www.greenterrafirma.com/vawt-designs.html
Take a look around the site…
Back to the gearing – this will increase your voltage. As long as you can use the higher voltage (more serial batteries) this will give you more watts. You’ll likely need 6 blades rather than 3, as mentioned earlier.
Good luck,
Bruce.
so how many batteries do you think i would need? 12 volt im assuming right?..yeah the furling i would definatly have to do ..i live in oswego ny..im about 5 blocks from lake ontario..and it gets really windy here..so serial batterys are batteries hooked in series?thanks again..this site rules
I want to build a homemade wind generator with a battery bank. I would like to use grid power as well as my generator to power my home, but I do not want send any excess (if there is any) back into the grid. I also do not want to have to install new outlets just for the generator power. I hope this made sense, what I want to know is how can I do this?
Basically what I want is to be able to utilize both systems without sending extra back into the grid. (That’s even more convoluted than my first paragraphs ain’t it?)
Paul,
As far as I’m aware, no one can legally connect an electrical generating device to the electrial grid, without the connection first being inspected and approved by the local electrical distribution utility. You would be better to explain your request to a local electrical contractor.
Connecting to the grid is serious business. Make a mistake and you could send power down the line when a utility worker believes the lines are dead.
I have already e-mailed both my local power company and the city building codes person to see if I can even legally do it.
I got another question. On a VAWT, is it fewer or more blades that increase torque?
Hi Paul,
On a VAWT, torque can be quite complicated. However, generally speaking, on a Darrieus type of VAWT, 3 blades produce more torque than 2 blades. T
Bruce:
Great blog/site, it has been helpful. I would like to possibly build my own residential wind turbine. As mentioned above, the number of motor’s available for sale on Ebay seem endless, but may not be right for me. Is there a formula that I can use to estimate my expected output in watts, knowing my average wind speed and the specs of a motor (rpm’s, volts, and amps)? This way, I can calculate the payback from building my own wind turbine. Thanks in advance.
Steve
I am going to build a wind turbine at my cabin using 2 DC motors. They both the same, (2x) 130 VDC @ 6750 RPM, 18.5 Amp. From what I understand, the voltage output varies linearly with rpm. I am going to gear up my system 5x so that a 150 RPM will turn each motor at 750 RPM and produce 14.4 Volts. My question is, do I need and voltage regulator (or something) to control rises and rops in voltage, and also, how does the current output vary with RPM.
If you are charging 12V batteries, you may need closer to 16V DC. That much gearing, could make the blades very difficult to start turning. You’ll need a diode in the circuit to ensure the current only flows towards the batteries and not back towards the generator when there is now wind. Without the diode, the batteries could turn the generator (motor) and blades backwards, till the batteries are drained. As you voltage goes down, so does your current…. current equals voltage divided by resistance. As the resistance of the cirucit does not change, the current will decrease as the voltage decrease.
hi bruce, i just came across your webpage, i went to a seminar here teaching how to make a wind mill, but i am first confused the turbine looks like a water pumping machine, tho its called dc motor generator, i will also like to know because the one that the seminar organizer used is a 1000watt dc motor generator with about 1500rpm in 12volt, is this good enough to generate and charge a battery of 12volt, 200amps battery without a problem like quick charges or something please i would appreciate if you could xplain this to me in details.
thanks
Also the Dc motor generator is 3 phase ..i hope that isnt a problem
Hi Holawalay,
Sounds like they have several blades, rather than the usual 3 blades. Using more blades increases your power (lifting power for example), but reduces the rotation speed of the blades. For a 1000 watt wind turbine, you would need blades that are at least 5 feet long… or more. That’s a diameter of 10 ft or more. If you use an off the shelf generator, rather than making an Axial Flux Alternator, then the voltage produced needs to be quite high at a low RPM. Take another look at your notes, as this size of blade likely turns at 150-200 RPM. Thus you would need 16 volts to be produced from your motor at 200 RPM.
Cheak out our site for more info:
Axial Flux Alternator:
http://greenterrafirma.com/axial-flux-alternator.html
DIY 100 Watt Wind Turbine:
http://greenterrafirma.com/DIY_Wind_Turbine.html
Making PVC Blades:
http://greenterrafirma.com/making-pvc-wind-turbine-blades.html
honestly bruce i am lost, first of all the DC generator as its likely called is a DC motor generator which its also called a turbine, but its 12volt 1000watts, its measure in watt no amps..the rpm again is 1500, the machine is small so i dont know if 5 blades with 5feet tall gonna fit, also do u mean the lower the rpm the quicker it produces charge into the battery?
please let me know the rules that govern the high rpm,watts as i can see you mentioned more of very little watt here and different volt instead of the 12volt..
Hi Holawalay,
If the motor takes 1500 RPM to generate 12 volts, then it’s no good for charging batteries. Please go back to the seminar leader and clarify what motor they used. Ask them what is the RPM speed of the wind turbine in a wind of 12mph. Then ask them what the voltage output is of the motor at that RPM.
You will need 16 volts to charge a 12 volt battery. You also need a deep discharge battery, not just a car battery.
I am thinking of building a watermill that will belt drive two permanent magnet motors wired in 3 phase ac. I was wondering if I could disconnect grid power to my house fuse box and wire my generator in with no batteries, what would I need inbetween the generator and fusebox(diodes,inverter,etc)
Also I am looking at a motor that produces 12 volts every 90rpm and supposedly at a 26-27 mph wind on a windmill produces about 500 watts. but it doesnt say anything about amps. what do u think?
Nathan – Hydro power is great if you have access to a constant flow of water. A couple of concerns with hydro – regulation and load. You need a consistent “quality” of electrical power – 120 volts and 60 hertz – thus you’ll need the proper electronics to guarantee this output before ever considering using your own power. If the voltage or cycles vary, you could damage a lot of items in your home!
Load – hydro electric systems produce power all day and all night. This power MUST be used. You need a proper system to ensure that a “load” is applied to the system to consume the power when you have no use for it…
For both of these reasons, it’s well worth installing a battery bank and the electronics to control it. Use your hydro power to charge the batteries and to supply a load when the batteries are fully charged (charge controller with integrated dump load). Then use electronics (inverter) to produce a grid quality output that you can feed to your fuse box .
This system may not be cheap, but if properly built, will last a long time and should have a reasonable payback..
Nathon – second question re: PMG amps – you can determine the amps if you know that the motor produces 500 watts at 12 volts – Amps = Watts/Volts. Thus in this case Amps = 500/12 = 41 amps.
Note – don’t let someone selling you a motor but NOT the blades, tell you what the power output is, at a certain wind speed. The power output at a certain wind speed will vary depending on the blade configuration – 2, 3 or 4 blades, 4,5,6 foot sweep area…
Lets say I were to just hook the system directly to the fuse box and go throught the steps to leave the grid connected also, then would I only need an inverter. Do you have any suggestions on a Specific motor for my applicatoin?
Thank you very much for your help.
If you want to connect directly to the fuse box, you will need a fused disconnect switch between the source and the grid-tie inverter. The grid-tie inverter then connects into the fuse box via a fused connection. Of course you’ll need to have the whole setup inspected or your home insurance will become void, etc….
Note: grid-tie inverters not only produce grid quality power, they also automatically disconnect power from the system should the grid power disappear – you don’t want your system to send power down the line, while linemen are working on the wires! As well, get a grid-tie inverter with a built-in dump load…. if the inverter disconnects power from the fuse box, you need that power to get consumed by something.
why not get a 5kw home gen and tear off the gas motor and hook the electric motor up to the hydro/wind power and then if needed(some come ready to run every household item) (cheap if bought used) run it through an inverter and hook it up too your house.
Hey there, I have a question. First off great comments. So I have an old treadmill motor rated at 10 amp-90 volt-4700 RPMS, can this be made into a wind turbine? Any info would be appreciated it.
thanks much
You need a motor that will provide 1 volt with every 25 rpm or less. The motor would require 50 rpm to produce 1 volt and is therefore no good for a wind turbine without a lot of gearing.
Hi Bruce,
I am planning to build a low cost wind turbine for use in remote areas where there is no grid power.
I have a motor with the following specs with me.
180v @ 1800 RPM, 6AMP PM Motor
I am planning to use a flywheel with a dia of 1 ft. connected to the shaft of the motor and 3 blades each with a length of 4.5 ft.
Do you think this will work for me. I will be charging 12v 100 AH batteries with this and use an invertor to run a refrigerator, TV and LED home lights.
Thanks,
GV
Hello GV,
Your voltage to RPM ratio is very good. The large length of the blades will mean they turn slower than a shorter blade. I might be a bit concerned with a wind gust breaking them… a smaller blade wouldn’t have the same pressures during a sudden change in wind direction. You might want to start with something closer to a 3 foot blade and work up. It’s nice if you have a couple of sets of blades in hand and a day with steady wind – then swap the blades during the same wind conditions and measure the results.
Bruce.
hi Bruce I have been messing with solar and wind for about 5 years now and I just got a nice motor it a JX motor it puts out 16 amps and 31 volt at 1000 rpm its a modlel MY1016 it says it puts out 200 watts but I dont realy know I just tested the amps and volts ,so do you think that will charge a bank of 4 12V battries?
Hi Mel,
Sounds like it would be a good motor, but your numbers seem quite high for a MY1016 style motor. Most of the specs I’ve seen would indicate that the motor produces 200 watts (11 amps at 24 volts) at a top RPM of around 2600. If that’s the case, and your wind turbine gets 500 RPM, then you would get about 500/2600 x 200 watts = 38 watts. Your voltage measurements seem high as well… if this is a 24 volt motor and you can only turn it at a fifth of the rated speed, then you would only get about 4.5 volts out of it… not enough to charge 12 volt batteries. Of course if you can gear up the motor to at least 1500 RPM, then you’d be able to charge a battery bank, producing close to 100 watts per hour.
Hi Bruce. I have a dc motor rated at 90v 4700 rpm 10 Amp What do you think about this motor as a wind generator?
Hi Dave,
In order to get 18v DC from this motor (to charge a DC battery bank), you’d need to run it at close to 1,000 RPM. This is much faster than a typical turbine will run. You couple possibly get the required RPM with a gearing system, but the AMPs would also be low. Thus, you can give it a try as a test or demo system, but a motor with lower RPM rating than 4700 or a higher DC voltage (230 rather than 90), would work much better.
I recently acquired three DC motors from work. They are condenser fan motors from a large Liebert chiller. They are rated for 1625 RPM 277V made by GE. Would this be sufficient to use for this application? I am just getting started with this project. My goal is to create a few systems one would be a field expedient system designed for camping. The other would power my shed and the third one is up in the air.
These sound like great motors for a DIY wind turbine as long as they are permanent magnets.
I am actually not sure how to tell if they are. I think they are variable reluctance. Another website I visited said to spin the motor and if it spins freely they are most likely that type. These motors do. Wondered if you had any input for that.
Likely the easiest way to tell is to put a volt meter across the leads… then spin the shaft. If you get a good voltage reading then you’re all set. You should also feel a slight “clogging” as you turn the shaft slowly. Do you have the GE model number on the motor?
Hey bruce, I was wondering if it possible to use the dc motor system that runs the fans in our computer to obtain electrical energy, on using the wind energy concept.
As those fans require almost no power to run, you’d also get “almost no power” out of them if you used the wind to turn them (at a high rpm).
well I guess I have the average treadmill motor I just picked up but seem to be a low efficiency unit I measured 54 rpm/ volt. will I then need to gear it up 2:1 to make it a 25 rpm / volt and work for a battery charger. I think it said 1.5 hp. motor.
Yes, at least 2:1.
Was thinking of attaching a motor to the central heating circulatiion pump of our house. When the heating is on (pump turning) , the system could be generating power. Possible or not ??
This falls under the “no free lunch” category… The extra power (electricity) required by the pump, to turn the generator, would be MORE than the electricity produced by the generator, due to conversion losses, friction, etc. You could damage the pump motor as well, or at least shorten it’s lifespan, depending on the size of the additional load.
You need a power source to turn your generator, that’s not costing you energy to create, such as falling water (hydro), wind, heat (sun or ground temperature).