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No voltage on Disk rotor-what am I doing wrong
By Reno, Section Wind Posted on Sun Jan 30th, 2005 at 09:38:40 PM MST
none

First off I am just trying a test coil and spinning by hand. It is 30 turns of 16g wire and I get .3V AC when spinning by hand. The rotor is 10 inched with 12 wedge type neos (the big ones). This leaves 1 inch between magnets and the coils inner void is the size of the magnet. I am assuming I should get more from one coil and will evenyually looking for about 3 volts.I checked and double checked the polarity of each magnet and it is correct. Comments please and thanks.

No voltage on Disk rotor-what am I doing wrong | 12 comments (12 topical, 0 editorial)

Re: No voltage on Disk rotor-what am I doing wrong (3.00 / 0) (#1)
by Flux on Sun Jan 30th, 2005 at 03:52:30 PM MST
(User Info)

How thick are those magnets?

Flux

Re: No voltage on Disk rotor-what am I doing wrong (3.00 / 0) (#2)
by windstuffnow (elenz(at)windstuffnow(dot)com) on Sun Jan 30th, 2005 at 04:25:09 PM MST
(User Info) http://www.windstuffnow.com/main

Are the start and end wires on the coil free of coating? Meter got good batteries? 1 inch is pretty wide ( my opinion )... assuming your getting a spin of around 100 rpm you should see around a volt or less (.96 volts I calculated) or around .032 volt per turn. If your looking at a cut in of around 200 rpm you'll need about 40 turns per coil using a 12pole/9coil 3 phase arrangement. You should try to get the gap down to around 5/8" to no more than 3/4". With #16 wire you should be able to wind them so they are no more than the 5/8" thick without any space problem. You can make the centers a little smaller side to side but keep the top and bottom of the coils as tall or slightly larger than the magnets.
Have Fun
Windstuff Ed

Have Fun! Windstuff Ed

Re: No voltage on Disk rotor-what am I doing wrong (3.00 / 0) (#3)
by Reno on Sun Jan 30th, 2005 at 07:46:39 PM MST
(User Info)

Hello
Yes i scraped the wire with a razor blade. I wasn't expecting much voltage but I thought I would get more than I am. My goal is for approx. 3Volts per coil. I want to wire the stator for 12V and if I can get 3V per coil wire each phase series/parallel. THis will allow to convert it to a 24V stator if in the future it is required. So the stator is going to have 36 coils 12 per phase. The 12/9 arrangement would not be suitable for a 12V system. I will try a larger coil and will probably go with 14 wire. The 16g is just for experimenting (it is what I have).

[ Parent ]

Re: No voltage on Disk rotor-what am I doing wrong (3.00 / 0) (#7)
by windstuffnow (elenz(at)windstuffnow(dot)com) on Mon Jan 31st, 2005 at 08:17:56 AM MST
(User Info) http://www.windstuffnow.com/main

If your using the 12/36 arrangement you can decrease the amount of turns and make them quite thin as well as increase your wire size. What is your cut in speed goal?

Windstuff Ed

Have Fun! Windstuff Ed
[ Parent ]

Re: No voltage on Disk rotor-what am I doing wrong (3.00 / 0) (#4)
by Greg Moore on Sun Jan 30th, 2005 at 08:18:07 PM MST
(User Info)

At the risk of hijacking this thread,

Ed you wrote:

"You should try to get the gap down to around 5/8" to no more than 3/4". "

Can you elaborate and explain what effect the spacing between the magnets on a given magnet rotor has?

Thanks in advance.

Greg

[ Parent ]

Re: No voltage on Disk rotor-what am I doing wrong (3.00 / 0) (#5)
by Flux on Mon Jan 31st, 2005 at 01:16:55 AM MST
(User Info)

If those magnets are the ones from Ed I seem to remember they are quite thin and for good results the gap should be kept down to less than 1/2" to use them to best effect.

The large wedge magnets that Dan used are thicker and would tolerate the 1" gap.

To get the best compromise between winding space and field strength you ought to work the magnets at their BH max point. This is where the flux density in the gap
is about 0.6 Tesla. For a dual rotor this happens roughly when the coils are the thickness of one magnet.

Because of the clearance space between magnets and coils wasting winding space, if the magnets are 1/4" or less in thickness I would increase the coil thickness to 1.5 x magnet thickness to gain more winding space.

Flux

[ Parent ]

Re: No voltage on Disk rotor-what am I doing wrong (3.00 / 0) (#6)
by windstuffnow (elenz(at)windstuffnow(dot)com) on Mon Jan 31st, 2005 at 08:10:02 AM MST
(User Info) http://www.windstuffnow.com/main

The gap between the magnets will control the amount of flux penetrating the coils, the larger the gap the lower the gauss,therfore, the smaller the gap the more power you can achieve. Neo's have a very small field in comparison to ceramics or others but its very intense close to the surface.
Using slotted silicon stators this isn't a problem because the magnets ride very close to the steel and the steel will focus the flux through the coils. It's quite common to see .8 - 1 tesla through the coils with a standard N35 grade neo. The dual rotor is different, it needs the magnets on the second rotor to "pull" the flux through the coils creating a fair magnetic path. The closer they are the better.
I tend to work economicly so I need the best bang for the money I spend on a project. I don't believe you have to spend twice as much to get the same power, you simply need to be more conservative in building. This depends, of course, on what your building and the power your looking to achieve but both go hand in hand whether its a 500 watt unit or a 5kw unit.

Have Fun
Windstuff Ed

Have Fun! Windstuff Ed
[ Parent ]

Re: No voltage on Disk rotor-what am I doing wrong (3.00 / 0) (#8)
by windstuffnow (elenz(at)windstuffnow(dot)com) on Mon Jan 31st, 2005 at 10:02:43 AM MST
(User Info) http://www.windstuffnow.com/main

Reno,
It just dawned on me what you may be doing. If you've made the coils to fit around the magnet then your only getting one pole per leg. The coil needs to be large enough to cover both legs with 2 magnets ( one north one south ). So, you need to make the coil so that each leg is centered on the poles of 2 magnets. With a 10" disc the magnets would be spaced about 2.61" from center to center on the od and 1.57" on the id. Your coils should be 2" tall or slightly taller ( 2.1" ), 2.61 at the top 1.57 at the bottom center to center. Triangular coils work best. Keep in mind if you wire it in star the voltage will be 1.732 x that of a single phase.

Have fun
Windstuff Ed

Have Fun! Windstuff Ed

Re: No voltage on Disk rotor-what am I doing wrong (3.00 / 0) (#9)
by Flux on Mon Jan 31st, 2005 at 10:43:38 AM MST
(User Info)

I think you are right, He is mixing up 2 ideas, if he is using a 12/36 arrangement the coils should be as you describe and the legs will be thinner than the gap between magnets.

He seems to be using coils intended for the 12/9 arrangement. If he is using your magnets and is using 12/36 as he stated, the hole in the coils will be considerably bigger than the magnet.

Flux

[ Parent ]

Re: No voltage on Disk rotor-what am I doing wrong (3.00 / 0) (#10)
by Reno on Mon Jan 31st, 2005 at 05:38:17 PM MST
(User Info)

Hello Ed
Yes I want 3 phases 12V each. my goal is to series 2 sets of 6 coils then parallel in each phase. I currently have a 12V system setup and to do the 12/9 set up for 12V would in my mind be a waste of potential. I will try a coil wound center to center to see what I get. As for the diameter I cannot go any smaller the hub I have has 5.5 in dia bolt holes and as it is now the threaded rod runs close to the coils.

[ Parent ]

Re: No voltage on Disk rotor-what am I doing wrong (3.00 / 0) (#11)
by windstuffnow (elenz(at)windstuffnow(dot)com) on Mon Jan 31st, 2005 at 07:16:40 PM MST
(User Info) http://www.windstuffnow.com/main

Actually, depending on the output your looking for the 12/9 would work fine. Using #14 wire your looking at around 50 amps of charging possibly more depending on your cut in speed. When you decide to change over to 24V simply make up a new stator. Thats just me though, I like having an excuse to build another one...

Have Fun
Windstuff Ed

Have Fun! Windstuff Ed
[ Parent ]

Re: No voltage on Disk rotor-what am I doing wrong (3.00 / 0) (#12)
by Reno on Tue Feb 1st, 2005 at 05:55:46 AM MST
(User Info)

thats true
I went over my notes and just realized I should be using 18 coils for this setup. I am using the diagram posted here, http://www.fieldlines.com/story/2003/8/30/142827/087
each phase will have 6 coils and each coil will have one magnet space between them
so I guess each phase will be series only. I made a coil with the center the size of the magnet and the legs the with of the space between magnets and I got over a volt and that is with only one rotor and the coil could definitely have been tighter. It looks like I have something to work with. I will be ordering 14g wire when I make the real coils. The next problem to solve is the threaded rod is in the way since the coils are much larger but that should be easy to work around. The funny thing is I had a 4.5 inch hub with bearing a little stiff and a friend of mine pulled 2 off a 2004 aztec so I took them being 5.5 inches I didn't realize the stator space would be greatly reduced at the time, oh well.

[ Parent ]

No voltage on Disk rotor-what am I doing wrong | 12 comments (12 topical, 0 editorial)

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