Low RPM / Low wind DC motor windmill

[CmeBREW]

Hello RE-group folks,

Here is the latest on my recent Low wind Leeson DC motor Hawt windmill. It actually exceeded my expectations and I am VERY happy with it.

It was discussed here:

http://www.fieldlines.com/story/2008/1/7/3321/39833

 I needed something quick, easy, and effective primarily in the lower winds for consistent daily power, and I must say I like it alot.  I was going to view this one just as a 'Back-up extra windmill' for a temporary use, but it is better than I had thought. Of course it is not as efficient as a brushless alternator with efficient wood blades though. (And I am using the nice alternator I had made previously for a Lenz2 Vawt) So I needed something quick and easy for a HAWT.

I am pleased with the results so far. Over the last few days it is doing an approximated average of 1200 WATTHOURS each day! Here is how I approxiamated it:

I have two 12v 115AH 'Marine/RV' batterys. Each night, I watch ONE HOUR of TV (140watts including the inverter usage)  from EACH battery. (2 hours of TV total)

And a few hours of 10W lighting also. It equals 300 watthours total that I take out of the two batts each night.

The next day, it only takes 3 hours to completely charge EACH battery fully. So this mill charges both batterys (300watthours total) in 6 hours.

Therefore, since there is 24 hours in a day, thats 300 x 4 = 1200 Watthours.

It generates good at night also, even though the breeze can sometimes be alittle less than daytime.

Yes, I think it is at least 4 times better than my small 4 foot mill above my roof. (maybe even more considering all things)

I painted it brownish grey to blend in better with the background and to be MUCH less noticable from the road about 1000 ft away. (and the neihbors)

Once the snow melts again it will be practically invisible. The blade rotor diameter is 6 feet and 9 inches.  It is only being tested now on a 8 ft. wooden pole because my truck brakes need work (again!) and so I couldnt get the steel pole/pipe yet. I had to make the tailboom and furling out of a wooden 2x8 for now.  I plan on putting it only on a 11 foot high pole primarily for looks and since the electric lines are fairly close and since I actually want it to be as 'unnoticable' as possible. These electric lines unfortunetly go down our back proper line (instead of out at the road)

This is the back side of my house and the dominate wind direction as you see the mill aimed. I live in a very hilly valley type location. So there is alot of 'up and down' wind gusts especially down near ground level. Its like a constant roller coaster effect.

And obviously because the mill is lower to the ground and at the corner of my house. So the main (Best)direction of the winds is down this big valley (not shown to the right) where 40 head of cattle are kept, and also many times from the direction of that big barn on the hill in the first picture.  

I am actually amazed at how good the wind is hitting my mill. I do not seem to see THAT much turbulance.

We actually live on the side of a big hilly valley. So the wind from the direction of the house is non-existent anyway-- since it goes up a very long big hill, hundreds of yards long, with many, many trees, barns, farms, and some houses.

But from the dominate direction(s) it is almost always generating something.(1-3amps)

Maybe the curvature of the PVC actually help with this turbulance?? I don't know-- but I think it is doing great.

Often times, the winds seem like they may even 'push off' the back of my house (to the left) as you see in the photo and then hit my mill effectively. This may even make it better in low winds this way? It sure seems possible. But of course, we all know the fact that the higher you can put a mill in the air the better it will perform.

It is nice that the dried out weeds along the fence will be barely moving and the mill is still generating alittle something all the time.  I must say I LOVE MORE SWEPT AREA !!! Can go wrong with more swept area!

The smart, experience guys keep saying that time and time again, and they're sure right.

The YAW AXIS is simply a 6" long 1/2" bolt that goes all the way thru with two big washers in the middle that have grease between them. It turns easily. I know, I know,,,I have to secure that wire!

I was surprised that the furling actually works! I quessed it perfectly on the first try. For this simple furling, I used two shed door type hinges for the whole mill to tilt back to a certain degree. You can see the STOP BLOCK I screwed on there so it don't go back too far. A big wind gust tilts it back automatically. I still need to put in a spring or big rubber band to pull it back down though. Didn't have time to do that today.

Anyway, it is usually doing 1-3 amps, but goes up to 7 amps when it furls at about 500rpm.  I am very pleased with the daily average watthours. I just need more batterys now.  I am going to take down "Passing Wind -200X" when a warm day comes. It is being retired. It was a great stepping stone, but this bigger one is MUCH better in consist daily watthours.

Any comments, questions, concerns, or wisdom, or advice, greatly appreciated!!

[elvin1949]

CmeBREW

 Nice looking mill.Don't take the other mill down

just get another battery or two and use both.

 Looks like you have a good location for wind.

I don't.I would have to put that mill up at 70 ft.

to get half the power you are getting with it on the ground.  KEEP HAVING FUN

later

Elvin

[Capt Slog]

Sounds like you're getting good performance from those modified blades, I for one, would like a template of them!  If you get the time and are willing to take the trouble, a decent from the front with a ruler by the blade would be a help.  I'm still trying to find an ideal shape for mine, it sounds as if you have it.

I used tilt up furling on an earlier project, and there is a problem with it if you have winds that change direction a lot, which you may or maynot be aware of.  If the turbine is spinning clockwise (viewed from the front) and yaws to the left, the result gyroscopic forces make it tilt upwards and furl when it shouldn't.  But it yaws to the right during a gust, the reverse effect tilts the turbine downwards and stops it from furling or at least adds extra 'weight' that it has to overcome to furl.

Cheers.

.

[Capt Slog]

a decent      from the front with a ruler

Please insert the word 'photo' in there.  :-)

[CmeBREW]

Thanks guys.

    Well my average Watthours was goofed up today. 'Light and variable' nothingness -- and if there was any tiny breeze whatsoever, it came from the one bad (worthless) direction up the big hill in the back. So there was ZERO wind today. Not even the dried weeds moved. That is still a fairly rare day in the wintertime for me. (maybe one day a week)

So today the mill did nothing.

However, the sun shone all day long and gave me about 100watt hour of power! (about 45 min. of TV)

I've been getting more sun this winter than last winter it seems.

However, tomorrow and the next day is decent winds again--so I will be back on track. Tomorrow is forecast to be 5-15mph and tomorrow night 10-20mph, and the next day is good too. I had forgot to mention that in my inital posting that these kind of winds just mentioned are the type of winds I had when I did the average watthours testing.

Actually the average winds here are not so good due to the hills and valleys. (under 10mph average)

But as you said I do have a fairly good and clear wind direction most of the time.

However, even on a decent wind day (10-20mph), the average winds are by far still mostly 10mph and under-- and this mill keeps spinning nice and charging some. And the blade rotor is so light that it picks up speed immediately with the winds. These thinner blades also 'coast' (keep spinning fast) very well thru 'up and down' turbulance.

When the blades were wider, it didn't do this very well.  

 





The dimensions of these blades can be found near the bottom of the link at the top of this story posting. These blades are actally 39.5" long.  I cut them out fast with a jigsaw, and let the jigsaw cut the way it wanted according to the curve of the pipe. And I just sanded the edges some with my finish sander. The trailing edge is still quite blunt-- I was too impatient to round it over.

I will keep you posted here on the accumulated Watthours of the next few days.

I will get a couple more 115AH batterys to have a better system.

Thanks.

[Bruce S]

CmeBrew;

 Wow what a beautiful country side :-) reminds me of the 9 acre grape farm up in Lakeshore, MI.

I sure would love to be able to put something like that up around the these city parts. Nice looking rig.

Cheers

Bruce S

[CmeBREW]

Thanks Bruce.  

Yes, the sunsets are amazing in that direction which is the West. And the most dominate wind direction comes down from that valley. We don't own any of those big fields-- The Ol' farmerman owns all of it and the big farm you see in the first photo. He's 82 years old and raises 40 head of cattle, and takes care of the farm mostly by himself. He's a real nice ol'fella. He's had triple by pass heart surgery and both knees replaced. He practically lives on his favorite tractor. An Amazing worker and an amazing farmer.

Well, I am still very pleased with this new mill. I am really amazed. Now I understand how much incredible FUN everyone else has been having with their 10 foot Hawts! WoW. I can now imagine how much Watthours you can get from a 10 footer.

I have continued to measure Watthours. I can see now that those first 3 days were quite the IDEAL type of wind days. So-called 10-20mph day AND night without any let-up. I still believe they would've been around 1200 Watthour days each. But obviously not every day can be windy and good as that.

Like today had about 8 hours in the afternoon where all the good wind (10-20) completly died off to nothing. But last night was 15-25mph. And right now and presumably all night tonight , it should be back up to 10-20mph , including tomorrow and the next day.   So the average winds in the wintertime are quite good around here, even down in these hills.

Happily, I have seen no problem with the tilt-back furling whatsoever. I know this sounds contradictory to what is commonly said, but this mill either has very little wind turbulance hitting it, or it 'handles' the turbulance extremely well.

It sorta 'freaks me out'.  It does GREAT even at this low level. I think I found a FAR better location than on my rooftop!

The YAWing is STEADY with this mill and its location.  Even though the Yaw axis turns very easily (especially with that long tail in a tiny breeze), the mill yaw axis stays good and steady in the directions. It does not ever move erratically, so therefore the FURLING also is working great.

I am VERY Happy with the furling. I quessed perfectly where I wanted it.

I went ahead and put the 'Rubberband furling' on it(until I can find just the right spring), and it works GREAT. Only took a minute to put on there:

ONly a BIG wind gust makes it furl all the way back.(probably 25mph+)

I have watched it furl many times now. It furls at about 6 amps which is fine. It still makes some power when fully furled.(I've seen 3 and 4 amps if the gust is big enough)

But sometimes it can take 30 seconds or more for it to come back down to the normal position after the strong wind gusts hits it and has passed. This seems to work out better this way.

I would rather it let the really BIG gusts pass by fully in the furled position , rather than the mill move up and down real fast.

I think I'll make a VIDEO of it furling in the bigger winds. It shakes the pole some since it is not cemented in the ground. Its ok for now I think.

Anyway, I am very pleased with anywhere from 500-1200 watthours in a fairly windy day/night.  I can finally start making a REAL system hooked up to some on my home lighting circuits and some dedicated wall circuits such as my TV.

I am certainly having FUN now. It was also sunny all day today.

I didnt want to leave my solar panel hooked to nothing while it is in the full sun, so I hooked it to my BIG 4watt treadmill motor floor fan (direct hook up), and it ran like a JET engine ALL DAY LONG!  ALOT of moving air.  Really neat.

Thanks.

[ghurd]

Now you have me wondering...

The PVC blades have very little twist.

The root looks too thin or narrow or not wide enough.  Might make it start harder, loose some torque and power in low wind.

Might try another set of blades, the same on the outer 2/3rds, but 'bigger' on the inner 1/3rd.  I bet it helps an awful lot.

It's only 10% of the power, but I believe it is a lot of the low wind torque.

Plus it will make them stronger.

You should go out and make them right now.  Nice night for it.  LOL.

My version of your fan runs well from a VW panel.  My files, TreadFan,jpg

G-

[CmeBREW]

Thanks Ghurd,

I see what you're saying. But thats the way the blades were initially-- much wider at the root side of the blades. But they were MUCH slower than the trimmed down version on it now. These thinner blades have MUCH less drag which means more CONSISTENT SPEED and more speed automatically means more torque. (I believe)

I am believing now that this must be true even in LOW winds also. And these thin blades get over the cogging and start up from a dead stop almost as easy as the wide blades. It still starts up in a tiny breeze because of the leverage of the almost 40" long blades. I LOVE what i'm seeing! It is doing exactly what I hoped it would do. I actually believe the MAIN best thing is the nice low rpm (cut-in) DC MOTOR--not just the thin PVC blades.  

I am going to keep using these blades for a good while. And it is -20 degress F. windchill (20-30mph) outside right now!  No testing today!

I did the approxiamated average daily Watthours for the week. Keep in mind though that I suspect it was a good week for the winds.

Looks like:

4. days would have done upto 1000-1200 watthours into batteries. (When I get a serious batt bank like that)
   
2. days would have done 500-600 watthours.
   
1. day had all sun but ZERO wind all day/night.
   
   

I did these tests by watching One hour of TV (140W / 27" color TV) and a few hours of 10watt lighting. (equals 150 Watthours each time)

I am sure in the future there will be such low to zero wind days that it will do only 100 or 200 watthours a day. Like I said, this was a good windy week.

On the fairly windy days it took 3 hours to re-charge battery to Full charge. (I obviously started with a full charge)

So thats 150 Watthours in 3 hours.(ONE battery)

On the less windy days it took 4 or 5 hours to re-charge to Full.

So I believe it is doing really good.

Another thing I noticed about these blades are that they are quite FLEXIBLE.

I think this is a GOOD thing. The blades act like 'shock absorbers' when the big turbulant wind gusts hit them. I can especially see it well at night with a flash light.  The blades flex back and forth somewhat with the big wind gusts. With the Gyroscopic forces, I would think this would be benefical for the ball bearings.

Today is the first Big wind day (20-30mph) to see how the furling is.

I tightened up the big rubber band alittle bit since it was spending too much time in the furled position. Now it works perfectly! It comes back down smoothly right after the big gusts.(2or3 seconds)

 Today it is doing ALOT of steady 4-6 amps and now furls nicely at 7 amps which is when it begins to make the 'wirling noise'.

It was VERY important to me that none of my distant neihbors could hear ANY 'wirling' noise at all from this mill even while they are standing outside.

And the furling accomplishes this perfectly. I've been watching the furling all day in these strong wind gusts, and it is SO COOL that it works so good!

However, in a 40+mph wind, I will have to shut the mill down. (The strong ceramic mags hold the blades back very well when the wires are shorted together)

As you can see in the photo, it is furled and the blades are actually moving fast in a big wind gust.

In a couple of months, we are having that big propane tank (on the right/not shown) moved to another location, and thats where I am going to re-locate this new mill to be further away from the turbulant corner of the house. (Actually,I had to trip the photo's width down or it messed up the spacing of the words very wide)

I forgot to mention that I painted the PVC blades and the motor with that KRYLON 'Fusion' spray paint. Its for painting plastics and PVC. I got mine at Wallymart. I used two different colors though. I first sprayed a brownish/red color--and then did a fast 'spatter' coat of light grey over the brown while it is wet. It melds together to be a brownish/grey color. The wood is painted with just normal exterior latex paint.

Anyway, I am having alot of fun and am now putting together a REAL usuful system.

I actually have two more of these nice motors. I might make another mill just like this one during a weekend to get more from those very low wind days.

P.S.  Nice looking treadmill motor fan ghurd.  It looks like it is going over 1000rpm!

You must have 24volt on it.  I guess it would be like 12-20 watts at 24v ??

Thanks all.