Author Topic: Wind Power (Read 2767 times)

kc5etv · « **on:** August 09, 2008, 03:06:08 AM »

Hello all, My name is Les I have just finished building a 10 foot wind power turbine going with the Otherpower format and seems to be working fine that is if we would get so wind, My question is if I build another wind turbine can I put them in parallel at low wind speeds to charge my 12 volt battier bank ?

kc5etv · « **Reply #1 on:** August 08, 2008, 09:19:45 PM »

That is in series not parallel...

wooferhound · « **Reply #2 on:** August 08, 2008, 10:09:15 PM »

The output of a wind turbine is an Alternating Current (AC) voltage. If you put the turbines in series, they will be "out of phase" half the time and you will get half the power output.

The proper way to do this is to feed each turbine into it's own Bridge Rectifier and the parallel the outputs of the rectifiers. this would then connect directly to the batteries along with a Dump Load Controller to keep your batteries from over charging.

kc5etv · « **Reply #3 on:** August 08, 2008, 10:20:30 PM »

Yes after it becomes DC, right now our winds are about 5 to 15 and at about 7 to 8 I have 7 to 8 volts DC so with two wired together I will get the voltage and amps I need... Thanks

wooferhound · « **Reply #4 on:** August 08, 2008, 10:31:14 PM »

If you wire the outputs of the bridge rectifiers in series, The Pulsating DC voltage from each bridge rectifier will be out of sync/phase with the output from the other bridge rectifier and you will only get about 60% of your generated power then. Or, it would be equal to the output from only a single generator.

kc5etv · « **Reply #5 on:** August 08, 2008, 10:33:57 PM »

My Wind turbine

kc5etv · « **Reply #6 on:** August 08, 2008, 10:45:47 PM »

If I use another bridge retifier in line to seperate the units will that help ?

wooferhound · « **Reply #7 on:** August 08, 2008, 10:52:23 PM »

Here are some links to help you . . .

http://www.fieldlines.com/story/2005/9/27/15317/0994

http://www.fieldlines.com/story/2005/12/26/33628/184

http://www.fieldlines.com/story/2008/2/23/211213/762

http://www.fieldlines.com/story/2007/11/12/221716/63

http://www.fieldlines.com/story/2004/3/14/62658/8673

Flux · « **Reply #8 on:** August 09, 2008, 12:52:58 AM »

Not sure how accurately you know your wind speed.

At 5 mph you have no chance of anything, there just isn't the energy in the wind. If you have everything right then you ought to see cut in at near 7mph and above that you should see results.

If your alternator cut in speed is too high then you may be loosing some low wind performance. I can't see properly from your picture but your blades look to have too much pitch. This again will mess up the low wind performance.

Using a second machine in series is questionable, in normal wind areas it doesn't

have much chance but if your wind is low and very consistent then it might work. but only in light winds.

You need to connect in series after the rectifier and the output of a 3 phase rectifier is sufficiently near smooth dc for the bit of ripple not to matter. The main snag is that the machines will generally not see the same wind at any instant and the low one dictates the output . You will have severe control problems in high wind. Also when you reach cut in you may stall both machines and fail to get much power beyond cut in.

Far better to sort out the problem with this machine and get it working right, then you could add a second one to potentially double the output.

Whatever happens you are not going to see much useful power below 8mph and if your wind speed is a guess then it may be working ok. Did you check cut in speed on the alternator when you built it?

Flux

kc5etv · « **Reply #9 on:** August 09, 2008, 08:04:27 AM »

Yes the wind has just been guess around here since I put it up so hard to tell what a have, as far as cut in the best I can tell it is between 8 and 10 mph that going with the local weather, I was watching the voltage going to the bat. bank and the amps and at one time we had a front to blow thru and I saw the amps as high as 9 amps and we think we had about 25 to 30 mph winds. I will keep working with this one till I make sure what she will do, One thing I have not put on yet is a charge controller and I am not sure whith way to go on that, I have 12- 2 volt bat. set up for my 12 volts system do you have any suggestions on that. Thanks for your help..Here are the blades on the table.

Flux · « **Reply #10 on:** August 09, 2008, 10:37:43 AM »

Local wind may be very different from that at the nearest weather station, but even so 9A at 12v from a 10ft machine in a 30 mph wind is a joke.

Your blades look odd from the picture and look even more odd on the mill. I think that may be a lot of your trouble if the alternator is built close to the spec.

At present I can see no need for a charge controller, that is a luxury that can wait until you have excess power.

Flux

TomW · « **Reply #11 on:** August 09, 2008, 10:47:16 AM »

Flux;

Yeah, that blade on the far left in the photo of the 3 blades on the bench looks a good bit different than the other 2 for sure. The pitch angles look steep on the assembled unit, also, but they both could be the camera angle, etc.

A steep pitch would seriously limit RPM and therefore power it seems.

Sure would be my first point to address for low output.

I am not a builder but do fly a couple turbines, so he should take my advice with a grain of "armchair" salt.

Tom

RUFUS · « **Reply #12 on:** August 09, 2008, 11:09:59 AM »

Thats a nice tower

is it telescopic?

what i mean is self raising,

i think the blade on the

left of the pic is upside down

nice work

Rufus

electronbaby · « **Reply #13 on:** August 09, 2008, 02:25:59 PM »

looks like his airfoils have a little too blunt of a leading edge. Also hard to tell, but the thickest part of the airfoil too close to the leading edge. Possibly could add to stall issues. Ive never made blades quite like that, but then again Ive had very good luck keeping it 1/3 back from the leading edge. I think Dan has some guidelines here:

http://otherpower.com/bladecarving.html

tanner0441 · « **Reply #14 on:** August 09, 2008, 02:52:05 PM »

Hi

Living in an area of poor wind and made lots of mistakes (some pointed out on this forum) looking at the blade chord. Going on the size of the table legs the blade look very narrow at the hub end and there seems to be little or no twist in the blades the airfoil also looks thick at the tip.

I have a single piece two blade prop which looks very similar in shape. It starts easily but does not speed up and has very little starting torque. The cogging on an Amtech type motor is enough to slow it down when coupled with an electric clutch from a car AC unit.

Hope this helps

Brian.

kc5etv · « **Reply #15 on:** August 09, 2008, 03:32:17 PM »

Yes you are right the blade is unside down and yes it is a crank up free standing and also brakes over in the back yard.. makes it nice.

kc5etv · « **Reply #16 on:** August 09, 2008, 03:58:21 PM »

I used this info the best I could but my problem was getting lumber that size, what I used was a 2 x 6 x 6 so not as much sureface. I will wait for a winding day and see how she does and if not good I will have to look around for some lumber of that size. Thanks for the help, by the way do you ever get on echolink ?

electronbaby · « **Reply #17 on:** August 09, 2008, 04:56:51 PM »

ok very good.

The majority of us, I think, laminate our own lumber. Its hard to find the dimensions you need sometimes and its just as simple to glue it together and carve it.

Echolink: I try to avoid it. I have this feeling thats its not real radio. Maybe Im crazy. I havent really been that active lately anyway, aside from some HF. I have a new 160M full wave going up this fall though.. we'll see.

Flux · « **Reply #18 on:** August 10, 2008, 01:41:13 AM »

You should get away with making the blades from 6 x 2, the main thing is the tips.

Your pitch angle ought to be no more than 3 deg at the tip and perhaps 6deg at half radius, it really doesn't matter much what you do with the inner third as long as it will support the tips.

The things seem to be far too thick at the tip and the angle looks way more than 3 deg.

May be an optical illusion but from the picture of the machine it looks as though the angle is nearer 30 deg at the tip.

Flux

kc5etv · « **Reply #19 on:** August 10, 2008, 09:49:40 AM »

Thanks I will check this out.

HaroldCR · « **Reply #20 on:** August 16, 2008, 08:04:26 AM »

Can you post a photo of the hub with the blades attached ?? Your Photos are very deceptive.

The guys are close to being spot on. The tips ARE too thick. The angle of the blade faces IS critical. Can you re-orient the blades to "Flatten" the face of the blades toward the wind ?? Takes a LOT of wind to overcome the forces of the blades traveling in the air, effectively "Dragging the brakes", so to speak.

You might think about a thin metal covering on the leading edge. You can't imagine what a small stick or something similar will do to a blade at ½ speed. Also, the wind striking the leading edge will erode the softer wood between the harder growth rings, and allow moisture to penetrate and throw off the balance, SEVERELY.

Someday, when you feel energetic, you could taper the tips from about 1/3 of the distance from the tip. A little more than 1/2 of what you have should be fine. 2 X 6 is what I used for my 4 KW machine, and I had a governor rigged up, to twist the 3 blades to spoil the wind power.

Worked GREAT, until a twister threw the blades off into the brush. Never fixed the unit. Sold out and left.

How are you guys balancing those machines for blade vibration. I strapped my setup, to my Farm Tractor FEL bucket, and drove it to the highest point in my field, and turned it into the wind. Mine would "Rock" a little at mid speed, but, not enough to cause any problem. I just let the top of the tower sway a little, to reduce the pull on the guy wires.

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Author Topic: Wind Power (Read 2767 times)