Here's a previous question and response about how to hook coils up.
"After reading your articles, I have decided to begin construction on a "Volvo" wind powered permanent magnet alternator as a supplement to a solar array on my property. I was hoping that you would be able to answer a few short questions with respect to the alternator design.
- Are the armature magnets used, all laid out with the same pole uppermost, or do they alternate?
- What is the formation and sequence for wiring the stator windings i.e. should each coil be wound in such a way as to produce a
final upper and lower tail, and then are they simply wired in series consecutively around the stator to produce the ultimate feed pair?
3 If the stator is to be split in two and the two halves run in parallel, is there any preferred connection sequence for the stator
windings, i.e. should they connected alternatively in series (A-B-A-B-A-B etc), or connect one entire side of the stator in series and
similarly for the other?
I would greatly appreciate any assistance with these questions. The mechanical side is straightforward - it is the electrical details
that I have problems with. I would be very interested in any other data/material that you have on the alternator construction and performance.
Thanks for your time. I am looking forward to starting this worthwhile project."
Dear xxxxxx ,
Welcome to the club of those addicted to making their own power!
Electricity is produced when a coil of wire is exposed to a changing magnetic field. If you just lay a big honkin' magnet next to a coil of wire, you get a short initial surge of voltage, then nothing. Thus, when you lay out the magnets on the armature, they alternate: N S N S N S N S N S. That's also why you always have an even number of magnets. Once you have your neos laid out, take one more loose magnet and go around the circle to double check. It should be repelled, attracted, repelled, attracted, repelled, attracted, etc.
There are two ways of winding and arranging your coils, both methods have their advocates. I will describe both. Both of these arrangements are for single phase alternators. Or don't worry about the method and just check the voltage as you assemble the machine. Since each coil is making AC electricity, there are only two ways of hooking up the next coil in the set, in phase or out of phase. As you wire up each additional coil, just make sure the voltage goes up rather than down (out of phase). If you want to try something more exotic like a three phase alternator, check out Ed's website. He has a very cogent explanation of three phase wiring. www.windstuffnow.com
Method 1. Wind every coil exactly the same way, eg all clockwise. Each coil has a start and a finish or end. Let's call the inner lead the start and the outer lead the end. Attach all the coils to your stator in exactly the same orientation, all clockwise. When you wire these up, you do NOT hook them up start, end, start, end, start, end. If you do it that way, each coil will cancel the voltage of the next coil. Rather, leave the start of coil 1 free, hook the end of the first coil to the end of the second coil. Hook the start of the second coil to the start of the third coil. Hook the end of the third coil to the end of the fourth coil. So its: end-end, start-start, end-end, start-start, etc. You will end up with two loose "starts" or "ends" as your final hook ups.
Method 2. Wind the odd coils clockwise (coils 1, 3, 5, 7, ect) wind the even coils counterclockwise (coils 2, 4, 6, etc). Install them on the stator to preserve the clockwise, counterclockwise, clockwise, counterclockwise orientation. IF you wind and install the coils this way, you hook the leads up so the end of coil 1 hooks to the start of coil 2, end of coil 2 hooks to start of coil 3, end of coil 3 hooks to start of coil 4, etc. You will be left with one loose start and one loose end as your final hook ups.
Deep breath and double check now. If you've done everything right with either method, here's how you check it. As you're making final connections, spin up the alternator and hook up coils one at a time. Each additional coil should make the voltage go up about the same amount, say 1.5 volts per additional coil for example.
Coil turns, wire size, coil size, coil shape, these are all subtle and complex factors that interact and affect your final output and performance of your alternator. There are a few formulas out there for predicting voltage and amperage output from a given coil, but ultimately, you will have to wind up a few test coils and test them under load to see what they will produce in your circumstances. Another option is to follow someone else's design very closely, you should get similar performance. Magnet wire and really good magnets are available from www.otherpower.com at a good price.
If you wire the stator in two halves, there is a preferred arrangement. It could be left half/right half with no problems (or top/bottom). It can't be every other coil because each "half" is wired in series and you can't hook every other coil in series in a single phase machine. So left half/right half would be the preferred method. This series/parallel arrangement cuts your voltage in half but doubles your amperage. This doesn't magically produce any more power (watts) but it may match your alternator to your blades better to get charging to occur at your favorite wind speed. Bigger wire (smaller AWG #) will give you the proper amps and volts with simple series wiring.
But it's always tricky to predict what the performance of any given alternator will be ahead of time, so take your best shot and see what you get. If you need to go series/parallel then no big deal. Small wire will give you more turns in the physical space you have available for coils. That will give you more voltage but less amps. Similarly, big wire will give you fewer turns in your coils, more amps but less volts. All other things being equal, you want the biggest wire that will give you the voltage you need because that minimizes the resistance of your stator assembly, which reduces heat and inefficiency. Whew!
Good luck and have fun!
troy
