wind

[Jason Wilkinson]

Happy New Year to all  Before i assemble i want to know if this is viable

Stator 15.5 in diam, 70 turns #14  12 coils 1/2 in thick

Rotor  13.5 in diam, 16  2*1*1/2 magnets per rotor    I plan to use 10ft diam blades. AT prerasent my system of 12in rotor 12mags  9 coils 35turns 2 in hand only produces 4 to 5 amps with the 10ft blades   would this "new" turbine produce more ?    thanks   Jason

[Flux]

"would this "new" turbine produce more ?    thanks   Jason"

Probably not!.  Most likely problem is the lack of wind.

Obviously I don't have all the details of your set up, your blades may be just planks or you may have far too much air gap or line resistance or something silly, I just don't have that information.

I checked your figures for the 12 magnet alternator and assuming reasonable grade magnets and a sensible air gap it looks ideal for an 8ft machine. If you are in a very low wind area then the 10ft blades are too slow. If you have any reasonable wind at all then either something is very wrong, badly built or there is some other factor that I can't imagine.

In a decent wind I fail to see why that machine shouldn't do far better. You are the only one who can decide if you do have wind, the fact that things shake and rattle and doors slam and trees shake is no real indication. If you could post some pictures of your set up then I may be able to form a better idea.

If the problem is lack of wind then the new alternator may do a little better but the only real way to get more in low wind is a larger prop and that again needs a bigger alternator and it becomes a vicious circle.

I assume that you are working at 12v, that winding is not suitable for higher voltage.

I think you will have done something terribly wrong to only see 60W from a 10ft machine. You need to find the cause before you invest a lot in magnet and copper.

Flux

[Jason Wilkinson]

Thanks again for your speedy response Flux,i've checked and rechecked everything  ie no reversal of coils in stator, all mags are orented n-s-n-s, front rotor N faces back rotor S i believe my error using too thin a rotor disc leaking too much flux. I've got strong winds here on the island 3/4 mile from the sea. No means of testing RPM but the old 10 footer puts out up to 20volts after the rec, i have 4 100ah batts connected in parallel and it took 2 days for the batt to move from 11v to 12.5v (i.ve just stop writing this post to make a voltage check and i'm seeing 12.2v at the batt and 18.9v open ckt) i still will try the 16 pole 12 coil 10ft and will try to post results    Thanks again Flux

                       Jason from Barbados W I.

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[Flux]

Jason

We have a bit more to go on now. It may be windy to you but I still think it is a low wind area but probably with consistent sea breezes.

20v open circuit is incredibly low if that is the maximum you ever see. With a 10ft machine running on no load on a windy site it would be fast almost to the point of being frightening and I would expect something up to 50v open circuit.

Thin discs will not help but unless they are less than 1/8" thick I think this is a minor issue. Do you have any idea of the cut in speed from hand cranking?. I would expect a cut in about 160 rpm with that winding. As I said that is probably about right for 8ft. It is rather fast for your 10ft blades if you really are in a low wind area.

Even so with your 20v open circuit it is implying a circuit resistance of over 1 ohm and that is high for a 12v machine and very high for a 10ft one.

Do you have any idea of the winding resistance or can you give me all the winding details so that I can make a guess. Is there a possibility that the thin discs are not running true and that has forced you to use a very wide air gap?

I am sure the 16 pole version will be better but your number of turns should throw you the other way with a low cut in and the problems of stall.

If we can sort out as much as possible from this alternator it will give us a better chance of making a better attempt at the new one.

Ideally I need cut in speed and winding resistance of the present alternator and I need to know more about your blades. Is it based on Hugh's or Dan's or is it based on something from a calculator.

Flux

[Flux]

Jason

I have just looked back through your earlier posts and I see that it is based on Dan's winding with 36 turns of 2 in hand #14. That should give you well over 5A with only 20v open circuit. I suspect that you may have far too much cable resistance between the mill and battery. I am still surprised at the low open circuit volts, that may imply a very large air gap or wrong angles on the blades or just low wind.

Flux

[CmeBREW]

Hi Jason,  

      Do you have any pictures of the mill?  That is sure a big mystery there. I wish I knew what was going on there so I don't do it in the future.  I had a couple questions if you wish to answer them.

Are you sure the blades are balanced? Did you follow Dans blade angles, especially at the tips?

Is the mill still about 350 feet away? Is that the distance to the batteries or are the batts near the mill? I believe you said a 12v battery bank all hooked in parallel.

 For only a 12 volt system the losses would certainly be horrible for that long distance without some giant gauge wire.   Can you tell us what gauge wire you are using for that long run?  

Sounds like you have done ALOT of work and have a great place for your mill there. Sounds like you have 2 mill now. YOu are ready for some real nice Watt-hours there if you could figure out the problem.

If you could just give alittle more information, Flux and others can help you get to the bottom of the problem --and then the rest of us 'beginners' can learn also , since there is ALOT to an entire system.

 

[Jason Wilkinson]

THanks for responding Cmebrew,i'll try to answer best i can, i did not follow blade design 100% i used exact 2*8 undressed pine for blades,rotor disc=11.5in diam 18 thick. Distance from house to tower base approx 90ft, base to gen 45 ft, If the (whosh-whosh) noist the blades make in the wind can be any indication of speed then i'm hearing about 40 in a 15sec period   giving a cut in of about 160 rpm. THe cable from gen to base is 2.5mm (3 in 1) and to the house is 1.5mm individual .YEs i have done quite a bit of work (a few mishaps 1) tower snapping in half 2)yaw bearing broke blades struck tower ALL 12 MAGS from 1 disc fell off  after 3 days searching i found them all ( PAINT YOUR MAG ROTORS GUYS )they were painted red. There are some photos of an earlier mishap  in my photo updates ( don't know how to link them to this post)Today the wind has dropped i calculate about 100 rpm  measured the rectified ac at the base and am only seeing 9.?? dc volts

 Yes Flux the mag disc are not true  there is a wobble in them. I believe the mags have lost some strength. Another thing i'm asuming the whoosh-whoosh is 1 rpm and not each blade

                 Jason

[Flux]

Jason

I have never had any luck trying to guess speed from the woosh noises, no doubt it can be done. Despite that, your estimated cut in of 160 rpm does seem reasonable for a fairly wide gap on that alternator.

This implies that the open circuit of 20v would have been at 266 rpm and that may come out at perhaps 12 mph so you are looking at low winds.

Is the cable 2.5mm dia or 2.5mm^2  Even at 2.5mm dia it would only be 5mm^2 which is small for that run at 12v. Any chance of trying into a temporary battery at base of tower, that would reduce cable resistance significantly. If it makes a big difference then look for heavier cable. If it makes no difference then it all points to lack of wind.

In this part of the world an open circuit machine will get up to a frightening roar on a windy day, there would be no question of identifying any woosh/woosh.

I have a feeling that you would do better with a cut in nearer 120 rpm. I think you could get it with your present magnets with a few more turns on the coils and a bit better mechanical set up. If you want to go for the 16 pole you may want to decide if it is worth going up to a 12ft prop but don't forget all the implications about increased alternator offset ( you may get real wind one day and want it to furl).

If you intend to keep to 10ft then the 16 pole would need about the same turns ( 35 ish). If you wanted to go up to 12 ft then it would be better to play safe and go up to about 40 turns and you could still use it at 10ft with a wider air gap. I have a feeling that you are going to need the largest blades you can manage with and you need not worry about the current carrying and burnout problems that others in windy areas have to face.

See if you can safely reduce the air gap on the present alternator even a mm reduction would help considerably and try the lower cable resistance before you do anything drastic.

Flux

[CmeBREW]

Jason,

      According to a wire gauge chart I have, that 1.5mm individual wire you mentioned is about eqivilent to 14ga wire here in the US I believe. The chart I have is here:

http://amasci.com/tesla/wire1.html

If thats the case, then As Flux said the resistance would be very bad at only 12volts.

You may need wire 3 times bigger than what you're using for that 95ft run.

Someone just posted a link about wire gauge size vs. loss, but I'm so tired I can't find it though.

 From what I've read from other's experiences, you could be losing HALF your power (Amps) thru that 95 foot long wire with that smaller gauge wire.

Have you done what Flux suggested and tested a 12v battery right below the mill?

That is certainly terrible all the unfortunate set backs you've had. It is a very good example for us all to not give up. -Hang in there, you'll get it.