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Forum Index : Windmills : Limited RPM.
| Author | Message | ||||
joyt12k Regular Member  Joined: 12/05/2009 Location: AustraliaPosts: 49 |
Help needed please. My charge controller seems to be controlling my rpm, as soon as it reaches around 27 volts the mill will not go any faster, If I disconect the positive to the charge controller the speed increases and the voltage increases. I posted a topic a few weeks ago on low amps, at the time there was no wind and I turned it by hand,I was getting 24v but only 1amp. It seems to be the same with the wind, the stator is a 2X7C. My other stator 7X2C allows the mill to go faster, but still limits the rpm when 27v is reached. Is this normal? 
jasmine |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Hi joyt12k Yeah thats perfectly normal. Your windmill is limited to 27volts by the battery bank and controller, and that 27 volts matches the rpm it seams to stop at. Its a limit of the turbine, it hasnt got enough power to push the RPM up above the 27 volt limit. If you have light winds, the 2X7C is the way to go, and for high winds the 7X2C. The 7X2C could make more power, but only if you have enough wind to drive it fast enough. If your only getting 1 or 2 amps, I would suggest you use the 2X7C and some bigger blades. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| joyt12k Regular Member Joined: 12/05/2009 Location: AustraliaPosts: 49 |
Ok, thanks, I've learned an awfull lot on this site over the last year. Will wait till November when the strong easterlies arrive. jasmine |
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| joyt12k Regular Member Joined: 12/05/2009 Location: AustraliaPosts: 49 |
Had some strong winds last night and managed to get 2amps out of it. A friend lent me his PL 20 charge controller, which gives all sorts of information. Does anyone know where to buy these from (made by Plasmatronics) Also have found in strong wind the mill is constantly changing direction, would a longer tail help? how does a long or short tail effect the mill. jasmine |
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Downwind Guru  Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Looking at your photo there seems to be no furling and just a tail stuck out the back. This is wrong and needs the tail offset. There is many adjustments you can make to the tail but you need to get the basics sorted first. Can you give a photo of the tail setup. Pete. Sometimes it just works |
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| joyt12k Regular Member Joined: 12/05/2009 Location: AustraliaPosts: 49 |
Ok, I have just gone up there in the dark and taken these, they are blurred because I couldn't see anything I just pointed in the right direction. Looking from the top, down, the centre distance between the shaft and tail is 150mm and the pivot point for the tail is 20 degrees in two directions. 
jasmine |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
It is hard to tell, but do the pivot for the tail slopes backwards only or back and to one side as the first photo shows it leaning to the right. The tail pivot should slope backwards only at around 15 degrees towards the tail, not left or right as well. The photos are clear but the angle is hard to tell. Pete. Sometimes it just works |
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| joyt12k Regular Member Joined: 12/05/2009 Location: AustraliaPosts: 49 |
Hi Pete, it slopes backwards 20 degrees and looking from the front slopes 20 degrees to the left, I'm pretty sure I got this information off this site, the bachward slope is fixed however the side slope is adjustable to upright. Thanks for any info. Ian jasmine |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Yes i think you are right with your tail pivot. Back to the tail. A larger or longer tail will have a greater dampering effect, so can adding weight to the tail. Adding weight will depend where you put it, the further out the tail the less weight required. I see tail length/size as a coarse adjustment and weight as a finer adjustment. Pete. Sometimes it just works |
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shawn Senior Member  Joined: 30/03/2010 Location: New ZealandPosts: 210 |
hi the tail looks short to me i found long works best, how long is it from pivot to end? and mine rests 10 degrees past straight behind there is a wind shadow behind the blades ,hope this makes sence. remember the tail should always stay down wind so it canot be to big its only the weight or angles that effect operation your angles look good. |
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| joyt12k Regular Member Joined: 12/05/2009 Location: AustraliaPosts: 49 |
Total length from pivot point to end of blade is 700mm. The tail was 2mm aluminium now it's 3mm galv sheet of the same dimensions, the aluminium was too light and actually went right around and fouled the prop, I now have a stop to limit it. jasmine |
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| shawn Senior Member Joined: 30/03/2010 Location: New ZealandPosts: 210 |
700 seams short to me others would no better than I. Do have a look at my posting (pictures to share)great long hunk of ugly wood but still flying and would be easy over 2 meters long. mill should not wave around unless wind changes direction or its furling. Ps high rpm will not hurt your motor but plastic blades can fly away and visit somewere else  |
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| joyt12k Regular Member Joined: 12/05/2009 Location: AustraliaPosts: 49 |
Have been trying various things over the past few weeks and given up on the F&P. I'm now building all the parts to take the PMA with raptor blades from Misouri Wind in the USA. This one won't need furling and it's very easy to copy their design, all the mesurements are there. jasmine |
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