My first AC motor conversion part II

[opo]

Hello again everybody. This project is far from beeing finished but I decided to share what I have done with it so far. The motor conversion is explained here:

http://www.fieldlines.com/story/2009/6/20/2407/40062

I have not had the time to take the motor back into the lathe since. But I like to do it eventually so that I can add more magnets. So far I have placed 30 HD magnets cutted in half to make two poles (so 60 pieces of half HD magnests about 4-5mm thick).

Work and stuff to do have prevented me from taking the rotor down to the lathe shop to turn it another 10mm so a second layer of magnets can be added and more reliable tests can be performed to match a set of bladesto it.

Instead I have built a set of 3 PVC blades 4ft dia, hub, tower and motor mounting with garbage that I found around. For the motor mounting I used a 4mm steel plate, a 3/4" flange and a section of 3/4" galvanized pipe which goes inside a 1" pipe used as tower. I actually use two 1" pipes bolted toghether but the motor mounts in one of them.

The motor as is, its been charging an old 12v car battery. Of course the generator stalls the blades (beeing PVC and the first set I made) I have only seen 2 amps. Unplugging the battery let the blades accelerate in gusts. The mill is mounted roof top and if the wind comes from the right direction the thing really flyes and sends bibrating noises inside the house (like a hum/air raid siren type).

Here are some pics of the Frankenmill:

http://www.fieldlines.com/images/scimages/13042/mill1.jpg

http://www.fieldlines.com/images/scimages/13042/mill2.jpg

http://www.fieldlines.com/images/scimages/13042/mill3.jpg

I have learned a lot from this project and from reading this forum. Thanks to everybody in this forum.

Octavio

[oztules]

Well Oztavia,

It's up, it's flying, and it's making some power.... that ticks all the boxes

The fun and the learning starts about now.... perhaps try  driving a 24v battery and see if the alt suits it better.

And a whole mess of other things to try.

...........oztules

[opo]

Thanks for your comment Oz,

Yes I will try it at 24v and see what happens and I also like to carve some wood/better blades for it. I figure I can go a little bit larger diam with wood blades, probably 5ft (1.5m) diam prop out of 2x4's. Its been a fun learning curve.

Cheers,

Octavio

[ghurd]

Great!

It makes it to about 2A pretty easy, then almost refuses to go past 2A?

I expect it is stalling when the blue-white and the yellow-green coils cut in.

The blades look a little narrow at the tips for the voltage I expected out of the conversion.

Might try another set just like them, but a bit wider at the tips.

Should give a lower TSR with a little more torque, maybe get it a bit more out of stall so it can get past 2A.

I just don't feel the narrow tips are adding any power at a low RPM.

Could try it at 18V, just for fun.  Still have the bad 12V with only 6V battery?

And 25W from a 4' is not so bad in "regular windy" wind. Especially for the first try!

G-

[opo]

Good Idea Ghurd. I'll try it at 12v + Xv with that dead 12v battery and see what happens with monsieur Ampere.

What I have observed is that it goes from 0 amps to 2 in no time in "good wind" (roof top mounted), actually in a second or two, but then it stays there and I can see the blades no longer accelerating.

I have some spare 8" pvc section to work on a fatter set of blades. Will do that also some day of this week and report back. I'm also trying to convince myself on carving wooden blades, out of 2x4 for piece of mind, so I might take the plunge on that also.

Thanks a lot,

Octavio

[ghurd]

Yes, it is stalling.

If the 8" PVC is in short supply, I myself would think adding 2~3" to each new blade would not hurt anything.  And I would still make the tips wider.

It is easier to cut it off than add it on.  

Adding 3" to each blade increases the swept area by 27%, or more depending on how it is measured, so 3" is not a trivial amount.

Side Note:  I tried for years to make one that stalled like that at about 2 or 3A,

without success.

G-

[kattos]

wooden blades are more dificult to turn at low winds for motors

[TomW]

kattos;

wooden blades are more dificult to turn at low winds for motors

Could you please explain how you came to this particular conclusion?

Tom

[opo]

Ghurd said:

"Side Note:  I tried for years to make one that stalled like that at about 2 or 3A,

without success."

Mine are a product of years of study and planning. ha! Must be called Taco-engeeniering.

Salud!

Octavio