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Forum Index : Windmills : Windmill Project
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| TechnologyPA Newbie  Joined: 10/09/2010 Location: United StatesPosts: 2 |
Hi All, I am a Technology Education teacher and am interested in building a wind turbine with my students. Due to issues with grid tie-in and the school building we would be looking to charge a 12v or bank of 12v batteries, which would likely be used on various projects (electric go-karts and such). I'm looking to hear of any successful or recommended experiences, designs or products that have been used and have a few questions. 1. I'm looking into generators and have looked at permanent magnet dc motors. Unfortunately it is difficult to get information about the amount of voltage and current output at a specific RPM. Has anyone worked with a specific motor or recommends a motor or other generator source? 2. Are there any recommended websites for plans or for parts that would be useful to work with on a limited budget? I appreciate any info you are willing to share! Thank you in advance! |
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AMACK Senior Member  Joined: 31/05/2009 Location: AustraliaPosts: 184 |
Hi TPA, Welcome to the back shed. There is alot of info on this site and there are other around all so. If you have time and can get someone to cut steel for you an axial flux mill would be good. There is a member that has made a small one out of light material and has a post in this section( Mack or MacGyver) It is only small but I think it would be a good project for education into mill and how they work. AMACK http://www.thebackshed.com/windmill/forum1/forum_posts.asp?T ID=2667&PN=4 It is on page 4 windmill section called "MacGyver's ax-fx build" *Note to self 1. Make it thick 2.Make it heavy. 3.Make it stronger than it should be. 4. Don't rush the first job as the second job will cost more and take mor |
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Perry Senior Member Joined: 19/11/2009 Location: Posts: 190 |
Hello, It depends on how much work you want to put into the project. On the easier side, you can get a PM motor or servo motor. There are many threads on this board that cover that. THen your task is primarily to make an adequate rotor and tower system. Most motors will have a rpm and voltage rating. You can divide to determine the number of revs you will need to hit your charging voltage, probably around 13.5 V for a 12V system. If you want to get further into it then you can build your own axial flux generator. There are tons of threads and plans that are all pretty much derivations of the same basic design. I guess a good question might be; How good is your wind resource. I think just about every noob in the field grossly overestimates the amount of wind they have and end up disappointed. Post some more facts and you will get lots of help here. Perry |
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| TechnologyPA Newbie Joined: 10/09/2010 Location: United StatesPosts: 2 |
I greatly appreciate the responses above! While the axial flux looks like a lot of fun, I don't think I'm going to have time to get that in depth with the students. I was looking at the PM dc motor route. The axial flux would certainly be a long term project. Our wind source is not great, but this would be a temporary project, one that students would build, test, alter it to make the design better and then take down. It would probably be up for a few months, and then put away for the summer until the following year. I really appreciate your time and responses! |
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MacGyver Guru  Joined: 12/05/2009 Location: United StatesPosts: 1329 |
TechnologyPA Give This Link a whirl! It says the entire build took only a day or two and without any fancy tools except maybe a band saw. You'll quickly find out that in order to get any appreciable amount of power, even 12-volts, it takes a lot of "swept area" (read that Large Blade), so for a student project, I'd keep the power goals down to maybe a volt or two and light LEDs to demonstrate the theory. . . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| Perry Senior Member Joined: 19/11/2009 Location: Posts: 190 |
If that is the case then it sounds like a PM is the way to go. Troll around ebay for DC Servo motors. For that sake, do a search on this board for them. Some have had good luck and they are quite rugged. Just a few more thoughts to shave months and dollars off your project. 1. Build a HAWT not a VAWT otherwise you will spend forever trying to get it to make power 2. Realize that a rotor and generator have to be selected symbiotically and this often is not a simple endeavor. Don't let me scare you, it's not terribly complex, just don't think you will get good perf by buying a gen and just slapping some blades on it. 3. Don't underestimate the cost of the tower. It will end up costing as much as the turbine and more if it is tall. 4. Steer clear of auto alternators Perry |
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Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
To be honest with you it is not a project that i would consider to be a short term activity, that you pop up and play with then pack it up. There is also the danger factor of these things whirling around at 200 - 500 rpm, and the quality of construction can make this a big risk. They are not toys!!!! I think you would be far better off doing small mills using stepper motors as a research project into wind behavior and blade designs, for a larger project into the future. There is so much to be learnt from mini mills and could be used as a design challenge. Place data loggers on the mini mills and record the power generated to a computer to see what really happens. What sort of mill do you have in mind a Vawt (vertical axle) or a Hawt (horizontal axle) i would recommend a Hawt as it is a far better design for harvesting wind energy. I think its great you are looking at doing this as an educational project but its a big step without prior knowledge. Please consider the dangers with a big mill as these can be very scary on a windy day. ( to the point you will RUN away) Your questions show you have very little knowledge of what you are about to enbark upon and need to consider all the factors, or the liabilitys could be very high. Pete. Sometimes it just works |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi TechPa I would like to recommend the little wind turbine kit I have purchased from Fillm on the forum, while it may seem expensive compared to to collecting bits and pieces, in the long term it will be more cost effective as a general rule the cheap way is more expensive in the long run. It has enough to do with mods to give a good project yet all the bits are there, and of good quality. and it has the advantage of a fully made tower that is easily dismantled if that's your purpose, with no parts to heavy or awkward to be carried by a couple of big kids. Some modifications to the electrics and reconfiguration of the blades make a good school project to learn by, and its slow airspeed to useful power production is very good, I would suggest a 24 volt unit set up as it works better as a real project not just as a globe lighter, as you need to encourage young minds to develop this type of energy source for the future. The add on controls are also a good learning tool, charge regulation, computer logging, battery management, and systems controls, and all at a practical and usable level, throw in a couple of solar panels and you could have a solar and turbine classroom to demonstrate all the aspects of alternate energy. Go for a school grant as the politicians are looking for reasons to be popular at the moment, so take advantage. All the best Bob Foolin Around |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
TechnologyPA Hi; me again. To add to what Pete brought up about safety, please be aware that some of these alternators make 3-phase alternating current, which can be lethal if you get mixed up in it the wrong way. I don't want to scare you off, I just think you should be aware of the potential safety hazard, depending on the size of the alternator and the wind speed. If you use a motor with "brushes" the commutator will in effect build direct current, which doesn't pose as much hazard at low voltages. There again, if the voltage produced is very high, safety issues arise. This will likely not be much of a problem with a small "demonstration" wind turbine, but I thought I should mention it. If your students are kids, I'd think twice about this. If your students are adults, I'd still think twice about this. If the a/c somehow gets down the tower before it's rectified, you could have a dandy liability problem. Like I said, a lot depends on how fast the thing gets going and how much voltage it pumps out, so taking those two things into consideration, gauge your project accordingly. . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Hmmm Bob, i think the freight to the states would rule a Phils mill out. One point Bob made is worth taking a little further and that is the use of solar with a mill. A windmill will not totally charge a battery and for this reason battery life is greatly reduced, so the addition of solar is a very good marriage. Why this??? What happens is a mill needs to be loaded all the time to either the battery or a dummy dump load. (or you will have a runnaway and it will fly to bits) As the voltage rises in a battery the amp absorption reduces, the load reduces and the mill voltage goes up, to the point the mill voltage rises above the allowable level of the battery, the charger controller then shunts all the mill power to the dump load. The battery is not fully charged at this point and needs a slower lower amps charge to top off the charging, and solar is very good for this. A mill is all or nothing with charging to a battery, and if the battery is low in charge and no wind then it sitting around without being charged is also a very bad thing, at least with solar you know there will always be something trickled in daily. Pete. Sometimes it just works |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
[Quote=Downwind]The battery is not fully charged at this point and needs a slower lower amps charge to top off the charging . . . Hmmmm . . . This might be a good place to use one of MacGyver's little toys, eh? 
. . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| Jarbar Senior Member Joined: 03/02/2008 Location: AustraliaPosts: 224 |
Pete,I think the mill is available in the USA at this link. http://oemwindpower.com/ Anthony. "Creativity is detirmined by the way you hold your tounge".My Father "Your generation will have to correct the problems made by mine".My Grandfather. |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Jarbar Thanks for the web site in the states I forgot to mention that in my previous post, interesting to note they are more expensive in the USA than here, thats a change, just shows how Phill is a good deal. All the best Bob Foolin Around |
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| Perry Senior Member Joined: 19/11/2009 Location: Posts: 190 |
Why such the AC hater?
At the same voltage DC is more dangerous than AC. Perry |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Hi Perry I had thought of this, but you gotta draw the line somewhere and my thought was if the AC were to get loose before it was rectified, there was more of a chance of 'wild AC' getting out of control with a burst of increased wind speed. I think I was concerned more with someone coming in contact with AC at a cycle equivalent to a heart beat, perhaps posing a danger of arrhythmia or the like. I'm no electrical engineer; it was just something to think about from a safety standpoint. From a personal point of view, I think DC has to be upwards of about 32 volts to nip at you, but AC at just about any voltage is uncomfortable. . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| Perry Senior Member Joined: 19/11/2009 Location: Posts: 190 |
Hey Mac, Wild AC refers to the alternating current varying in voltage and freq. Not wild like coming to get you, or out of control. With a wind burst DC will go up just as AC will. AC can cause a defib and is it's main safety point. DC will cause other issues such as burning and trauma. Saying that AC at any voltage is uncomfortable is just not true. Just keeping you honest here Mac. Not to give you a hard time but you are giving this guy info warning him about safety issues and your facts aren't right. I think when people hear AC they immediately think of the AC that comes from the wall socket with it's associated voltage and ability to provide current. Rectifying AC into DC is not a 'safety system' Perry |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Perry is 100% correct, but the point Mac was trying to make is also correct in a roundabout way. Mac's point is a unloaded mill can generate voltages high enough to kill you, and its an issue often pointed out here on the forum that just because its a generator dont mean the voltages cannot reach a lethal level. 
I must say i had a chuckle with the thought of the "Wild AC" coming down the tower and chasing you around the yard like an angry snake.
Pete. Sometimes it just works |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Pete Sounds like a wild politician but more useful Bob Foolin Around |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Perry Okay, just trying to help. I guess I'll keep my comments to my own builds from now on. . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Hi Bob, There is a few politicians i would like to see rectumfired and connected to a battery. Guess where i would like to stick the jumper leads. Pete. Sometimes it just works |
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