Ceining Fan Generator

[Jim Mac]

Hopefully we can spruce these forums up.. So I am going to post my smaller project I have been experimenting with.
I took a ceiling fan motor and cracked the shell. Removed the metal ring and epoxy'ed 64 neodymium magnets to the shell. Alternating polarity of course.

http://store.unexplainable.net/stuff/windmill/neos-glued.jpg

A little spray foam and the dremmel, and I'm all set.

http://store.unexplainable.net/stuff/windmill/mags-complete.jpg

Get a nut that fits the threads on the shaft, and weld the nut to a galvanized pipe flange. Run the wires down the middle.

http://store.unexplainable.net/stuff/windmill/mount.jpg

http://store.unexplainable.net/stuff/windmill/watts-220.jpg

There is some cogging. I am probably going to dremmel the edges of the magnets down before I seal the motor shell.

[Rob Beckers]

That's the neatest thing Jim!
What are you going to put on it? VAWT? HAWT?

-RoB-

[Jim Mac]

That's the neatest thing Jim!
What are you going to put on it? VAWT? HAWT?

-RoB-

Hi Rob,

I am leaning towards a Vawt with this motor. My other post has pictures of my upcoming HAWT, which is under construction.

I am a complete newbie who is yet to complete his first working mill that makes power. I don't really want to buy one, I like tinkering.

I am just grasping the concept that even though the motor can reach 270 watts with light bulbs, the low impedance load from a deep cycle 12V battery pulls like 1/10th of the wattage. About 26 watts when charging. I have just been referred to "Buck Converters" on another forum, which (as I understand) helps match the low impedance load to the high impedance alternator.

Seems like I am still missing the key to turn this possible wattage to usable wattage. If you have any good links to windmill electronics documentation, throw them my way:push:

[Rob Beckers]

Hi Jim,

Tinkering is good! Keep it coming.

Alternators are current limited; they just won't deliver more than a certain amount (though depending on the alternator that may be enough to burn it up!). Your alternator produces a fairly high voltage, since you are able to run light bulbs on it, at a relatively small current. The battery fixes the voltage, in your case around 14 Volt or so, pushing the alternator to deliver its maximum current for the RPM that it's running at. Since power is for the most part current times voltage, the result is very little power. Maximum power out of the alternator would be where that product of voltage and current is largest.

Buck converters are essentially just transformers for DC. They take high voltage and low current on the input, and transform it to a lower voltage and higher current on the output. You could also use a regular AC transformer to do the same, and get more power out of the alternator that way. Downside of regular transformers is that when the alternator is not spinning, or spinning very slowly (so the frequency is low), they form essentially a short-circuit. That combines poorly with wind turbines, where little energy is available in the low wind speeds where it would normally start spinning. The transformer load keeps the blades stalled, preventing it from starting until a much higher wind speed. Some manufacturers do use a transformer though, so they can have a higher voltage alternator (and thinner wiring if you need to go long distance), while still being able to charge batteries directly.

If you have any transformers lying around you can try that. People have designed small buck converters on the Otherpower board. Maybe you can give one of those a try.

-RoB-

[Jim Mac]

Thanks for the explanation. It was very thorough and easy to digest. Just what I was looking for.

It seems that the alternator is limited to somewhere around 1.8 Amps. But the Vawt will never come close to the rpms needed to reach that. So on windy days, I'm hoping to see it read over 1 amp.

I did a simple rpm test which suggests that 125 RPM will produce 6.6 watts of 12V charging power. I actually have a video demonstrating the rpm-power test here http://www.youtube.com/watch?v=4zNmO34QPYk If you want to skip the BS, just jump to 6 minutes or so.


I will be posting further videos as I progress, and my past videos show my learning curve. Before I mess with the big hawt, I want to understand all these basic principles. My charge controller/dump diverter should be here any day now:cool: