Winding wire type and type of winding

[Alkemi]

Hello All, I'm in process of starting a generator project and would love to get your experienced views / guidance so I won't make any mistake on this project. 
1] Does it make any difference if I use flat magnet wire instead of round one?
2] Also do I have to make sure that flat side cuts the flux i.e. flat side of wire facing magnet or it doesn't matter? [I got 14 awg flat wire, but when it arrived, I noticed that it is very very difficult to wind it in such a way that flat side will face magnet / flux lines]
3] Is wave or serpentine winding better or individual round coils?

Any comments / guidance / experience sharing?

[AzSun]

With a conventional coil, the voltage developed is all about the # of turns wire you can cram in the space available. Current capacity is determined by cross sectional area of the wire. In theory, using flat wire will increase your current capability as you will not have wasted space between the turns as you do round wire. It desn't matter which way the wire is facing but try to wind it in a manner the gives you the most amount of turns. I'm not sure about question #3. 

[Frank S]

you wouldn't want to wind serpentine if I get your meaning this would mean you would wind from inside to outside  wire width then start from inside again and wind out trying to do this would mean you would have a single strand going from out to in which would take up the same amount of space as a layer of coil see the problem?
 Wind your coils just like the line on a bait cast fishing real I think would be the way to go. IMO

[Flux]

Not enough details of what you are doing to help much.

With thick flat wire (strip) you will have less eddy loss if the flux passes along the long axis of the strip but at 14 gauge you aren't really thick enough to worry much.

In theory you can get a better stacking factor with flat wire but in real life without a great deal of care and effort there is not likely to be much gain. For simplicity I suggest you wind the wire the easy way and in most cases that will be the way that gives less eddy loss. Unless you can do a very clever transposition at the ends I doubt that you will get much better stacking than round wire. You will probably get better stacking winding it on edge but that is not easy without the right equipment and it will be worse for eddy loss.

In reality unless you are using a mppt converter you will have to tolerate resistive loss to get some sort of matching to the prop, you have the wire, stick with it, but in future use round.

Without more details it is impossible to comment on the type of winding, round coils suit round magnets for an air gap design, if the magnets are any other shape then make the coils a similar shape.

Wave winding is a reasonable option for slotted iron cores but is not easy to do with air gap machines and really isn't worth the trouble, you will have all the problems of overlapped coil designs and for axial machines you will not do much better than the usual single layer winding that most peple use ( 4/3 magnet coil ratio).

Flux

[AzSun]

Not enough details of what you are doing to help much.

With thick flat wire (strip) you will have less eddy loss if the flux passes along the long axis of the strip but at 14 gauge you aren't really thick enough to worry much.

In theory you can get a better stacking factor with flat wire but in real life without a great deal of care and effort there is not likely to be much gain. For simplicity I suggest you wind the wire the easy way and in most cases that will be the way that gives less eddy loss. Unless you can do a very clever transposition at the ends I doubt that you will get much better stacking than round wire. You will probably get better stacking winding it on edge but that is not easy without the right equipment and it will be worse for eddy loss.

In reality unless you are using a mppt converter you will have to tolerate resistive loss to get some sort of matching to the prop, you have the wire, stick with it, but in future use round.

Without more details it is impossible to comment on the type of winding, round coils suit round magnets for an air gap design, if the magnets are any other shape then make the coils a similar shape.

Wave winding is a reasonable option for slotted iron cores but is not easy to do with air gap machines and really isn't worth the trouble, you will have all the problems of overlapped coil designs and for axial machines you will not do much better than the usual single layer winding that most peple use ( 4/3 magnet coil ratio).

Flux

Ge winds their DC locomotive traction motor field coils as shown in the photo. It took quite an effort to develop the equipment to make that bend as it is a solid piece of copper. This was done to increase motor performance but not sure if it was related to eddy current or not. 

[Flux]

No there is no eddy current problem with field coils. Most large machine field coils are wound strip on edge as you show. It is a difficult process but gives far better thermal performance.

This type of construction doesn't work for air gap alternators. In the days when such machines were built commercially in fairly big sizes the eddy current issue was a real problem and the solution was complex and costly. Sadly most of this knowledge has been lost over the years.

Flux

[Alkemi]

Thank you all for the inputs.
I have 3 x 1 x 0.5 inch Neo Mags of about 1.4T.
I was thinking to wind them by hand in Serpentine way one round at a time and no machinery. I'll punch nails in the plywood exactly on the corners of 3x1 inch rectangle as guide lines. Finish the the winding from bottom of the nail to top and then start second layer from top to bottom and so on. The spacing in between magnets is exactly 1 inch. I have enough magnets lying around that I could even place them next to each other with no gap but is it advisable? Would it help in something? Also when I draw more current from genny, would having no gap in magnets help in reducing the effort to turn the genny? Or how I can reduce the effort?
Note: I'm using only plywood, magnets and copper coils and no iron anywhere except bearing and shaft and on top of that I'll have only one stator and one rotor.

[hiker]

heres one of mine i did a few years back-12" rotors -9&12 ..
used ceramic mags with neo"s on top of ceramics..hit 400watts at 28v using a
aircraft landing lite for a load-powered by a pedgen..could only hold that load
for a few secounds..i belive i posted a vid back then ?
its all made from wood as well--just the rotors -bearings and  stator mounts  are
metal...made a few over the years like this--last one lasted 5-6 years before the
bearings had to be replaced--i mount them on my motorhome...good luck with yours..................

[hiker]

heres a older one i flew on the back of my motorhome...it withstood wind gusts
up to 50 - 60 mph..  gets damm windy along the coast line where i test the mills out...fun stufffffffffffffffffff.........

[Flux]

I hope that by no iron you only refer to the stator. You need the magnets placed on steel discs to do much good. Sticking them on plywood will give near useless results.

The single rotor arrangement is inefficient in the use of magnets even on a steel disc and best avoided, with open magnets it will be so inefficient that you could do better with cheap ferrite magnets on steel discs.

Don't use round coils with the rectangular magnets. The gap of 1" between magnets will be fine. You will gain little by cramming them together. The work required to turn it will depend on what you get out. Anything that makes it easier to turn will reduce the output, you can't get something for nothing.

The serpentine winding seems a good idea on the face of it and it will work nicely for the first turns round your nails, when you come to build up the following layers you will hit trouble ( I think FrankS alluded to this). on the outside it will be ok but on the inside nails your wire needs to be under the existing turns or your wires will have to cross and make an almighty mess in the region where you ought to be keeping things tidy to get a good stacking factor.

With a lot of thought you can wind a big loop of wire and weave this in and out of the stator. You need the loop size exact and you really need slots to guide you and again I don't think you will do any better than with round wire as individual turns will slip about without machinery.

I really think your better option is to stick with conventional rectangular coils wound on a former, that way you can get the wire to lie flat and orderly and make best use of it.

Flux

[hiker]

by the way i didnt use that tv anttena mount for my mill[test stand]--i used a pipe resting on my rear bumper-that was clamped to the motorhome ladder--long enough for the blades to clear the roof...worked best with the motorhome facing the wind.....

[Alkemi]

you wouldn't want to wind serpentine if I get your meaning this would mean you would wind from inside to outside  wire width then start from inside again and wind out trying to do this would mean you would have a single strand going from out to in which would take up the same amount of space as a layer of coil see the problem?
 Wind your coils just like the line on a bait cast fishing real I think would be the way to go. IMO

Hi Frank, realized the issue when you brought it up, but then I thought about it and then got a way to avoid the issue you mentioned. It's little tricky, instead of taking the wire straight from Out to In and have gap, I thought to slide it from outside corner to inside from beneath the first round and keep doing it for further rounds. And this thing can be distributed evenly. Hope you got what I described.
Hopefully what AzSun said is correct, because I was thinking if flat area is cutting the flux, it will create more current than thin side of the wire and according to AzSun it doesn't matter.

[Frank S]

I thought about that as well. not too difficult with round but tricky with ribbon and as mentioned with little or no gains  in efficiency. also doing it like you described might make the coils more difficult  to adjust the turn count I would think 

[electrondady1]

"Hello All, I'm in process of starting a generator project and would love to get your experienced views / guidance so I won't make any mistake on this project." 

one of the most experienced builders on the site has advised you .
place your mags on 2 iron/steel disks.
use round wire to form rectangular coils.

using flat wire in the way you describe will maximize eddy currents and heat in your stator.
heat in your stator is bad .

[Alkemi]

ElectronDady, I truly admire Flux and have great respect for him. He is almost 99.99% correct. What I'm trying is gradually going there. My Stator coil is not molded into plywood. It would be tied in initial experiment. Same way for Magnets. I can improve on it by using Iron core and then add another rotor. This way I'll have all calculations of core less, single rotor, dual rotor and then with core output of the generator.

There are some videos on Youtube I have seen, which gives very high output (in the range of 100+ volts) with half the effort of bicycling. I'm not sure those guys are trying to fool viewers or encourage, but I'm willing to learn / verify it by spending little more time and money.