Voltage much less than expected

[(unknown)]

I have enjoyed reading this board for several months now and the temptation became too great, so I jumped in and started to build my own windmill.

I am only getting about 1.5 volts AC out of my 3 phase generator when I give it a good hand spin. Dan in one of his nicely documented presentations claims that one should see at least 10 volts. My rotors are 16 inch dia. with 12 rare earth magnets each. The magnets are donut shaped 3 and a quarter inch dia. with a one inch hole and half an inch thick. My coils are two stands of no 17 AGW magnet wire and have 40 turns each, a total of 9 coils, 3 in series (120 degrees apart) for each phase. The donut shape stator is slighly less than half inch thick and the air gap between the rotors and stator is about one eight of an inch. I have a few pictures of all this in my photo upload posted on this board because a picture is worth a thousand words. Could it be that the lack of any spacing between my magnets on each rotor is the source of my very low voltage reading ? All comments welcome and appreciated.

Regards

  Leo  

[Flux]

Your pictures are far too big for me to wait for them on dial up, but I did see enough to realise that your magnets are too close together and I am convinced they are not rare earth but ceramic and that is the main reason for the low output.

I think you may do better reducing to 8 poles on those discs to have a better magnet spacing. You could double up the magnets on 1 disc (one on top of the other).

Use 6 coils. Even so with ceramic you will have to increase turns and be satisfied with a fairly low output.

Flux

[ghurd]

They look like microwave magnets to me.

The pics don't show how big the coils are compared to the magnets, but they seem a little small.  The center (hole) of the coil should be as big as the outside of the magnets.

Maybe you could change the magnets to 2" neos?  You could use what you have, and it would not cost TOO much.  (it never costs much if it is someone elses money  )

Maybe 3/8" of each side of each magnet could be cut off, then double them up?

Could each existing coil be rewired, one of the starts to one of the ends, to give 80 turns of #17?

I hate starting over.

Thinking out loud.

G-

[wooferhound]

I'm seeing that the coils are the same size as the magnet

the hole in the coil should be the same size as the magnet

the magnets should be able to almost pass through the hole in the coil

The magnets look like  they came from microwave ovens so they will be Ceramic

[Gary D]

You could wire up the unit in star, rectify it,and test it at known speeds. Then you'll get an idea of the cut in speed and amps at certain speeds... you may have a usable high speed small diameter unit (although not what you were hoping for). When rectified, and the phases added, you will see a higher voltage...Just a thought. Gary D

[(unknown)]

The friend that gave me the magnets I guess knows very little about magnets, he told me that they were rare earth, but I believe you are right about ceramic and were designed for microwave ovens. That makes sense to me. I will buy proper magnets and also make a new stator with larger coils. Thanks to all those who responded, I may try some of your sugestions. If I do I will let you know how it turn out. Thanks again.

Sorry about the oversize pictures. (another mistake I will try to avoid)

Cheers!   Leo

[ghurd]

Leo,

Let us know what you do and how it works (or doesn't).

You got a lot done, so don't give up now!

G-

[picmacmillan]

hi leo...looks like you did a real good job on your genny...just the magnets are not any good...maybe for holding tarps down ...i have put a picture of my cardboard cutout of one of my stators, with a couple test coils...one coil(red) is 200 turns of #15 wire, this was my first attempt and was too high in resistance...the second coil(brown) is of 2 strands of #14 wire, 30 turns...this second one worked well and fit well....i would suggest on your next stator that you may want to use 2 strands if you are going to use thin wire like #17(just a suggestion)...as this will emmulate thicker wire and give you more current...you for sure are going to have to get better magnets and you will be happy with your results.....also in my picture are round cardboard cutouts...they were my magnets which were 1 inch diameter and 1 inch high neo's (that was all i could afford at the time)...the cardboard template shows how big the inside of the coils should be for the magnets to fit in...they could have in fact been not as high, but again, it is a learning curve...i believe you have a good setup there and for the parts and wire you are working with, it will give you some decent power....maybe not as much as some, but for sure more than others....i am looking forward to seeing your completed project.......pickster

[ghurd]

The rest looks OK to me (still learning- I did much worse that almost worked!).  It would probably work with smaller neo magnets, like round 1-1/2" or 2" X 1/8" or 3/16"-ish?  A poor guess.

You still there?

G-