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Low RPM / Low wind DC motor windmill | 8 comments (8 topical, editorial)
Re: Low RPM / Low wind DC motor windmill (3.00 / 0) (#8)
by CmeBREW (smke833f@hotmail.com) on Sun Jan 20th, 2008 at 01:25:52 PM MST
(User Info)

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:

  1. 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.
  3. 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.



Low RPM / Low wind DC motor windmill | 8 comments (8 topical, 0 editorial)

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