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Forum Index : Windmills : What magnets??
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arewa Newbie  Joined: 24/10/2010 Location: NigeriaPosts: 11 |
Hello, Pls, i would like to know if the magnets from a car kick starter work in a wind turbine? How can i know what type of magnets it is but they all have N & S aranged in it before i removed them and aranged them on a disk rotor. I tested a single coil slightly smaller in diameter of the magnets with the meter but no current flowing. Happiness starts with the begining of knowledge |
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| kevindion Regular Member  Joined: 28/07/2010 Location: ChinaPosts: 59 |
my magnets are out of electric bike moto. |
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Downwind Guru  Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
The magnet needs to pass over the coil at a very close distance but not touch the coil. This is why we mount them on plate steel, as well as it gives a return path for the magnetic flux. The coil should be larger than the magnet and the centre hole in the coil should be the same size (or close to) the magnet size, the exception to this is when the coil is wound around a metal object (iron core) You did have the meter set to AC volts didnt you?? It will be only a very low reading on the meter like 1 or 2 volts. What do you call a "kick starter"? as if you mean a starter motor from a car i didnt think they had magnets but field windings instead. Pete. Sometimes it just works |
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| arewa Newbie Joined: 24/10/2010 Location: NigeriaPosts: 11 |
Actually the magnets are from a car alternator not the starter, my mistake. And the coils are now in series of six coils together. does this mean the magnets on the disk as NSNS will generate or do they have another setting on the rotor? Magnet is 2 inches wide and the spacing to the next magnet is 3 inch. Coil width is 2.5 inch and spacing from one coil to the next is 3 inches. Happiness starts with the begining of knowledge |
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| itsandbits1 Regular Member Joined: 13/08/2010 Location: CanadaPosts: 81 |
I think you got an alterator some one turned into a pma and should have left the magnets on the rotor because you probably had one of what you are trying to build already.Unless it is some kind of specialty arrangement I haven't seen before. |
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MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
arewa A picture would do wonders. Just take one with a digital camera, upload it to your computer somewhere, then in the "Post Reply" box, click on the little picture of the tree with the arrow and follow directions. That way, we can better see what you're dealing with. In General: The ideal arrangement is a ratio of 4:3 magnets-to-coils. A "test coil" is wound of any size wire you have and placed in between the magnets while they are spun past it. This will tell you how many turns per volt. Once you know this magic number, you can use the largest wire you have (or several small wires turned at once, called "in hand") to make your coils with as many turns as you need, but still fit the space the coils have to sit in. It is always good to know what your expectations are. For example, if you're going to be charging a 12-volt battery, it would be best to wind a coil that when placed between your spinning magnets, produces about 1.8 volts. When you run it in series with other coils and then tie it in star, it'll give you a bit better than 12 volts, which is necessary to overcome the battery voltage and charge the thing. That's down the road a bit, so for now, just wind and test a test coil. Each "leg" or side of the individual coil should be approximately as thick as your magnets are wide and they should be spaced so as to give about half-a-magnet's-individual width between magnets. This lets you use up your "real estate" as many here call it to its best advantage. For "round" magnets, I tend to make each coil leg about 3/4 as wide as an individual magnet; it works better. Never allow both a -N- face and a -S- face to cross the same "leg" of a coil at the same time or it "cancels" the induced charge. Arrange things so as a -N- face passes the first "leg" of a coil, a -S- face passes the other leg of that same coil. This induces a current from each side of the same coil in the same direction. Try not to wind your coils in a "flemish". That means like taking a rope and while holding it on a flat surface, starting a wind at the center, then moving out so the more turns, the larger the diameter of the thing is. Don't do this! It results in massive cancellation. Like I said earlier; a picture would make it a lot easier for us to direct your efforts. . . . . . . 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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| arewa Newbie Joined: 24/10/2010 Location: NigeriaPosts: 11 |
Hello Mac, Here are description on pictures of the rotor and stator discs. the coil is guage #29 
Magnets are N-S-N-S 
Coils are in Series Happiness starts with the begining of knowledge |
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| kevindion Regular Member Joined: 28/07/2010 Location: ChinaPosts: 59 |
mine magnets just the same as yours. but i mount them on the wood not on the steel. |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
I see a few things wrong with both of what you guys have done??? Firstly why have you mounted your coils on a steel plate?? Secondly mounting your magnets on a wooden plate is wrong too. The magnets need to be mounted on steel so as to complete the flux path of the magnet, ...wood is not good. I am all for trying things, but some rules need to not be broken to get the best out of your build. Pete. Sometimes it just works |
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| arewa Newbie Joined: 24/10/2010 Location: NigeriaPosts: 11 |
Okay, Does this mean the coil on metal plate absorbes the field? Secondly, does the gap of the magnets matter? Also, i read something about coiling that: if the first is turned clockwise, the next need to be counter-clockwise.. does this law really matters? Happiness starts with the begining of knowledge |
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Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Yes, I thought that was an odd idea too, perhaps learning to walk might help before attempting an alternator building marathon  .
BTW Pete, there *is* a possible place for magnets on a wooden plate, it would be on the middle rotor of a 3 rotor machine  . I built one but used perspex instead and the round magnets were sunk into holes in it. Klaus |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Good point Tinker but i don't think it is the case with kevindion. arewa The metal coil plate will cause drag on the alternator and make it stiff to turn. Normally you would have a metal plate either side of the coils and magnets of opposite polarity on both plates, so as each magnet passes over a coil it has a north magnet one side of the coil and a south magnet the other side of the coil. You may be better with the magnets and coils 90 degrees to how you show them. I take it this is a single phase generator. I am not sure what you mean by [quote]Also, i read something about coiling that: if the first is turned clockwise, the next need to be counter-clockwise.. does this law really matters?[/quote] I thing you mean how the coils are placed in the stator...if so........... As for the coil windings and the direction of the windings, they will all need to be in the same direction and not reversed to one another or they will cancel each other out. Also the wire that is in the centre of the coil needs to connect to the wire on the outside of the next coil and so on to series them correctly. With your coils so far apart you will have a very noisy generator, as you will get a donk, donk, donk noise as the magnets pass the coils. Also your electrical wave out will be very strange with a peak and a big flat spot in between each peak. Adding more coils will help and more magnets will increase the results greatly. Your coils look to be different sizes and different shapes to each other and also different number of turns of wire on different coils, and if so, this is not good in all 3 cases. (bit hard to tell from the photo) I don't mean to sound harsh, but you are putting a lot of work into a rather poor generator here. If you are doing this for a bit of fun and don't mind a poor result then continue on, if you are trying to make something of a reasonable output than you will be disappointed with the results for all the work you put in. Pete. Sometimes it just works |
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| Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Pete, looking at that 'intriguing' design again, which I think is supposed to be a single phase affair, a thought occurred to me. What if the fellow has only 4 magnets? Could he then fit the magnets on one steel disk and have the second blank steel disk also rotating on the shaft, with the fixed stator (coil) plate sandwiched in between the two? It would not cog. It won't be as effective as having magnets on each plate but much better than having only one magnet rotor. Klaus |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Hi Klaus, Yes that will work, and has been done by several others on a different forum. It is still a lesser design and needs very close air gaps, and with the curve shape of these magnets will add to making it even less efficient. I often feel i am being negative to peoples designs, but also feel not saying anything dont help others learn and work to improve their creations. I think with only 4 magnets and big gaps between each coil, it will be like driving with square wheels on your car. With limited magnet strength it will be very dificult to stop the mill becoming a runaway in reasonable wind. My guess is it will preform poorly and will self destruct in good wind, as a runaway. There is as much work in making a lesser mill, as there is in a good one, but the magnet cost is the big difference. Although we should no loose sight of the fun factor we get form building something. Pete. Sometimes it just works |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Arewa & Crew Before this gets too out of hand, I think I can shed some light on the subject. For most of those here, this will be on the order of "Sandbox Electricity" or "Electricity 101" but it needs to be said before everyone gets all confused. By the way, don't feel like the Lone Ranger. We all had to go through this to gain a working understanding before building "successful" projects. I went through it with John Tulloch and bless his soul, he didn't commit suicide before it finally suck into my thick scull. That's just to say you're not alone in this; read on: 
Study this picture and study it well. It is a basic generator. When a wire is passed through a magnetic field, it generates a current (and voltage). This does not show a completed circuit, but for learning purposes, it's an excellent representation of what actually happens. Two things are of the upmost importance here: Wire size and direction of movement. Wire size determines the internal resistance to the flow of electrons, subsequently labeled "Resistance". It comes into play (down the road) in a formula E = I R The "E" stands for "electro--motive force" but we refer to it as "Voltage". Many persons use the same formula with a "V" instead of an "E", but the purists use an E (go figure!). At any rate, the voltage is directly proportional to the current (I) multiplied by the resistance (R). It is an algebraic formula and hosts all the functions of any other formula, so you can determine an unknown if the other two are known and so on. Direction of Travel: It matters which way the wire travels through the magnetic field. When I'm designing stuff (toys mostly) I designate a wire traveling through a N field (north-to-south) as creating a current in the "up" direction (completely arbitrary), so I can keep track of things. When the wire travels through the same field orientation, but going the other direction, the current in the wire travels the opposite direction. This is Key. Don't read any further until you understand this. Now, a wire traveling the same direction in the opposite field orientation S (south-to-north) produces a current in the opposite direction. Make sure you understand this thoroughly before reading further. This brings to light a few important facts: A wire traveling through a N field produces current flowing in the same direction as it does traveling through the opposite field (S) in the opposite direction. Make sure you understand this before going any further. It's of the upmost importance. Knowledge is only half the equation; the completed equation includes understanding. Okay, now that we have the basics under our belt, lets hop to a coil. A coil is just many loops of the same wire traveling in the same direction. Still with me? As long as the field orientation and direction of travel match up, current (and voltage) is created in the wire. If we goof this up, we get what is called "cancellation". Cancellation happens when the same wire passes through both a N and a S field orientation at the same moment. By this time, you should be able to tell me why. So; Why? Exactly, the field along with the motion of the wire bundle (coil) produces the same current through the same wire, but in opposite directions and they cancel. Get it? If you don't get it, start over and read through this again. Do some doodling on a piece of paper or whatever it takes, but understand this before you start building or you'll be inventing new "blue" words! I'm personally in a position where my tools are locked away for 5 more months, so I can't build any little show-'n-tell projects to show you what I'm talking about. You'll just have to use your imagination. What I will tell you is this: I have developed a different way to wind the axial flux alternator that doubles its output with no muss, no fuss. As soon as I can build a new stator, I'll post the pictures and all the grimy details here. For those who want to build something other than an axial-flux rig, I've figured out a way to use a single-magnet rotor with four times the output just by winding the coils differently. As much as Oz would disagree with me, that little picture is KEY! Learn it well and it will serve you well. And by the way, this forum owes a great debt of gratitude to that fellow even if he's no longer a poster here. . . . . . 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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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
[Quote=arewa]Also, i read something about coiling that: if the first is turned clockwise, the next need to be counter-clockwise.. does this law really matters? Before you read this, study the tutorial I just posted. At any rate, what's happening here is this: I think I know where you read this business about alternating the winding direction on alternate coils Here perhaps?. It's true; that works. What you need to understand is this is a method of attaching the coils in series to increase the voltage produced. It matters as to how the wires in each coil pass through the flux-field orientations to work properly. If you try this method, remember to follow the rules I've laid out in the above-mentioned tutorial or it won't work for diddly squat! Edit: Added hot link. . . . . . 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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GWatPE Senior Member  Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi Mac, I think that many readers will benefit from a lot of what you have posted above, but the quotes I have selected above are a bit ambitious, without further info. I do not wish to detract from arewa's original post, so I will create a new thread here should you or others wish to comment "Stator Winding placement options". Gordon. become more energy aware |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Gordon It's commin'; just be patient. I'm in a bit of a fix not having my machinery at hand and all, but rest assured, it's commin'. When the time comes, I'll have built a show-'n-tell piece with a tutorial and all. The "twice the output" one is actually nothing new, just a different way to wind a dual-rotor axial-flux. It'll likely work no better than the "traditional" way, but it's less parts and less work and just plain "cool"! As for the "four-times-the-output" one, that's just over-the-top cool. You're gonna flip. But, like I said, both are a ways off in the future. I have a court date December 8th. I'll know more after that. For those who aren't aware of my present predicament, I'm in prison (married) but looking forward to springing myself by March 17, 2011 or maybe sooner. Meanwhile, I'll check out your new thread and if I can work up a drawing or two, I'll post it, but if I had my 'druthers, I'd rather have already completed the project. I think I have enough parts from other projects to slam together a simple show-'n-tell presentation for the 4x situation, so maybe I'll do that and post it on your new thread. If you study the little .gif in a post or two back, you'll be able to come up with what I've done; it's rather obvious, really. And now that I think of it, perhaps 4x is a bit of an over statement. What happens is instead of a magnet pair producing a current in one direction, then in the opposite direction (alternating current), it happens 4 times each pass of the magnet pair, with each individual induced current traveling in the same direction in the same coil. I'm going to wait a bit to post what I've done, just to see if anyone can figure it out as I have. Study that little picture! . . . . . 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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| arewa Newbie Joined: 24/10/2010 Location: NigeriaPosts: 11 |
Hi Mac, The reason for the coils on the metal disk was to make the magnetic field stronger on the coils and also to avoid using two disc rotors. If it had worked well, i would have convert it to 3phase with more magnets. This is my first W.T project, so i wanted it as easy as possible using the metalic stator(sort of). Does this mean i Must have 2 rotor discs to make the alternator work? Downwind Regards to the clockwise and counterclockwise coiling, take a look at http://www.otherpower.com/wood103.pdf Happiness starts with the begining of knowledge |
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| Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Yes, if you want it to work reasonably well. Use one rotor disk only if you are after a very poor performance. Klaus |
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