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Forum Index : Windmills : F&P won’t spin on 12 v system
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GaryP Newbie  Joined: 01/06/2011 Location: AustraliaPosts: 15 |
Have trawled through but can't find any similar problem so here goes. I have an unmodified 80S stator which I have now decogged. Unloaded it spins beautifully and makes lots of volts eg 60v when spun by hand. When I hook this up to my 12 V charge controller and batteries, which is effectively a dump controller, it is as if the motor is shorted and barely spins. ie takes a big effort to spin it by hand. Volts go up to 12 immediately with 1 amp. Wind would never spin it. When I actually short out the motor it is even harder which I expected. I know it needs rewiring! Now the 7x2c is what is recommended. My concern is that I am going to go to all the trouble of rewiring and find it still doesn't spin. I don't really mind if I don't get lots of amps out of it, I just want it to spin. Has anyone else tried the unmodified stator and found it hardly spins? Will the 7x2c make a magic difference? Here is my connection setup. 
$@#&*....the word often heard in my shed when it doesn't go to plan! |
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Tinker Guru  Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Gary, a connected meter puts about zero load on your F&P - easy to spin. A 12V battery puts *heaps* of load on your F&P if its unmodified. Try to connect a 12V light bulb (10-20Watts) to it to see it producing power while spun by hand. Klaus |
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| Air Bender Senior Member  Joined: 25/01/2011 Location: AustraliaPosts: 206 |
Hi Gary The set up you have there looks identical to mine. Mine will spin freely untill the voltage output reaches 12 volt which is somewhere around 40-60 rpms. so up to these rpms it spins very freely. After it reaches these it starts to become loaded up. When it reaches around 1 amp it becomes very hard to spin you either need a strong wind or a big windmill to push the amps up higher. If your batterys are flat a load will come on as soon as you start spinning it, but if your batterys are charged it should spin freely at slow rpms untill the output reaches and excedes the voltage in your battery. I beleive that running the 7x2c set up, the load will start to come on at a higher rpm as it is puting out less volts but there will be more loading when it does come on as you are producing more amps. I have had no experience running a 7x2c but i am guessing this is what happens, some one else may be able to come in here. All the best Dean |
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| GaryP Newbie Joined: 01/06/2011 Location: AustraliaPosts: 15 |
Thanks Klaus and Dean, Klaus, I will try the 12 volt bulb and see what happens just to see what the load feels like. Dean, My charge controller has a dump load on it so if the battery reaches full charge it won't let it spin freely. Having said that, as it stands unmodified I don't believe the wind would ever push this around unless the blades were massive. The diameter of HAWT I am aiming for is about 1.6m. I'm in the Melbourne suburbs. What I really need to know is if the 7x2c will actually spin significantly easier than the unmodified stator or should I be looking at another wiring config. For what it's worth, I currently run a treadmill motor through this system and it spins to 12 volts and creates 2 amps easily. So it seems it is just the wiring and magnets that make the F&P hard to spin? Any others have a 12 volt solution? $@#&*....the word often heard in my shed when it doesn't go to plan! |
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| Air Bender Senior Member Joined: 25/01/2011 Location: AustraliaPosts: 206 |
Hi Gary My mill definatly has a load on it at around 1 amp, as it starts pushing past this in strong winds it starts to trist the tower this would be hard to do by hand as it is made of two peices of angle iron with spacers welded across them. It would be very hard to turn the shaft by hand at this point but when you add diameter to the shaft you also add leverage, and there is an old saying, give me a big enough lever and i could lift the world. I hope someone else can tell us weather wiring the stator to a 7x2c will reduce this load as i would be interested to know as well. All the best Dean. |
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| GaryP Newbie Joined: 01/06/2011 Location: AustraliaPosts: 15 |
Hi Dean, What diameter blades and how many are you using and how high is your tower? This is my current set up which is for a small but heavy treadmill motor. It produces 6 volts at best, which is why I'm replacing this with an F&P motor. Treadmill motor specs (120v, 5amps, 4000rpm) mean it needs much higher rpm to achieve anything. A lot of work for nothing really. Just looks good when it spins. Will be aiming for a sturdier pole/tower for the f&P. Was considering using the same fly wheel to attach to the shaft of the F&P but will need boring out. Current radius of blade (pvc) is 75cm. 
$@#&*....the word often heard in my shed when it doesn't go to plan! |
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fillm Guru Joined: 10/02/2007 Location: AustraliaPosts: 730 |
Dean, You have already said the answer " I KNOW IT NEEDS REWIRING "- rewire it and try it again. I would suggest 2x7p Delta for 12v, and even then the cut in might be to low and stall the blades, especially if they are just PVC pipe blades . An unmodified stator in 12V star, which is what you have there will be producing amps below 30rpm . You will notice if you spin it very slowly there will be no load untill cut in and then it will load very quickly and heavily PhillM ...Oz Wind Engineering..Wind Turbine Kits 500W - 5000W ~ F&P Dual Kits ~ GOE222Blades- Voltage Control Parts ------- Tower kits |
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| GaryP Newbie Joined: 01/06/2011 Location: AustraliaPosts: 15 |
Thanks Fillm, I've been reading this forum all morning looking for other tried and tested rewiring options. Is 7x2c the same as 2x7p? I know some will laugh at the question but I think my brain needs rewiring to understand the whole rewiring concept. I didn't think I was dumb but I was mistaken. Fillm, you stated "I would suggest 2x7p Delta for 12v, and even then the cut in might be to low and stall the blades" So if this is not an adequate solution, is there a better one? ? cutting away part of the stator, ?staggered rewiring. Stalling blades sounds a problem given there is already some resistance with mild cogging. I am happy for my mill not to produce huge watts. My blade diameters are limited by where I live so can't go the 10' blades seen on some youtube sites. May need to add a blade or 2 for more torque at the lower revs. $@#&*....the word often heard in my shed when it doesn't go to plan! |
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| Air Bender Senior Member Joined: 25/01/2011 Location: AustraliaPosts: 206 |
Hi Gary Im running a vawt with a 1.75 m diameter 3 wing rotor the wings are 1 m high. When I entered this forum I was told the wings would be a bit small and should be around 2 m to run the F/P with a vawt and they were right but it manages to get going when the wind gets up a bit and I manage to make a little bit of power. But i aiming to build bigger wings down the track.[Around 2m] Your mill being a hawt will run at quite a bit more rpms than mine so a 7x2c might be the set up you need But weather you will have enough torque you probably need to talk to someone who has built a few F/P hawt projects for that answer. My tower is around 5 m high and pivots in the middle so it is only the top 2.5 m that starts to twist. It only twists by a few degrees at the moment so i am not real concerned about it. You should not have this problem as your shaft is horizontal, but still may have the same kind of forces on it but in a different direction. All the best Dean |
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| Air Bender Senior Member Joined: 25/01/2011 Location: AustraliaPosts: 206 |
Hi Gary I missed Fillms post while i was typing the last one so his sugestion of the 2x7p is what i would take notice of, as i said the 2x7c might be the go. All these different ways of rewiring are still a bit of a mystery to me to but learning can be the best part. All the best Dean. |
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| GaryP Newbie Joined: 01/06/2011 Location: AustraliaPosts: 15 |
Thanks Dean, Unless someone has some magic answers I will now start the rewiring process to a 7x2 and if that fails maybe a VAWT is the go. Thanks Gary $@#&*....the word often heard in my shed when it doesn't go to plan! |
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| Xmaswiz Regular Member  Joined: 14/04/2011 Location: United StatesPosts: 69 |
keep us posted on the re-wire, and if you go to VAWT. Santa Maria, CA. Noel |
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| GaryP Newbie Joined: 01/06/2011 Location: AustraliaPosts: 15 |
Hi Noel, Have just completed the rewire 7x2c. Decogged it as well by rounding the poles. Now gets to 12 volts when spun by hand at about 120rpm ie unloaded. I tried it loaded spinning by hand and it certainly now spins fairly freely and gets to 12 volts. I couldn't spin it faster by hand but saw the Amp meter just starting to flick upward. I am still on a HAWT project as I want to use the old infrastructure and am not far off reconstructing it. I really need the wind to spin this faster to check the amp output. I will post images when the project is done. Hopefully a couple of weeks away. 
So far promising. I like the fact that if you can get another stator, you can just replace it rewired in another config to get a different output. Have one in the wings if this one doesn't produce the goods! Cheers Gary $@#&*....the word often heard in my shed when it doesn't go to plan! |
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