What went wrong? 1st alternator

[Aaron]

Hello,

Here is my first attempt to produce some electricity, it didn't work but I'm not discouraged. Anyone have any ideas about what I could do different on the next one? I'd like to see what I can do with the existing rotor and scrap the stator. Here's the ingredients...........I used 16 neos 2'' by 1/2'' by 1/4'' on a 9'' steel disk. The stator is a 11" piece of plywood with cold rolled insulated (masking taped) laminates imbedded in,and 16 coils each with 40 turns of #18 wire. The enamel has been removed from the tips. The opening is large enough for a magnet to pass through. The air gap is adjustable and remains even during rotation. I'm only seeing a flicker on my multimeter set on mA and its not steady but jumps up and down. It does not increase with other coils no matter what the arrangement. Any ideas? I'm thinking I need way more turns but maybe thats not it at all. Thanks in advance for any help!

[DanB]

Hi Aaron -

that looks like it ought to work...

• do the magnets alternate in polarity?  (N S N S etc.. around the disk)
  
• did you wind all the coils the same direction and lay them all down with the same side up?  If so... they should be wired
  
  

start - start - end - end - start - start etc..

- are you measuring for AC Volts?

You can check the coil connections:

First measure the output (AC Volts) from one coil while spinning at a known rpm.

Then check across two coils (if its double,you got it - if its 0 - you got it backwards)

Once you get two right, then move on to the next two - it should be double the output of 1 coil, or... 0 - if its 0 you got the connections reversed.  If things are reversed its an easy fix since you have all the connections outside the stator.

Does it turn fairly freely, or is it very stiff to turn?  Its possible - if you layed the coils right over the laminates that 2 or more could have shorted to the laminates.  Probably not very likely though... but possible.  If that happened, you can probably fix it by skipping one coil (take it out of the circuit) or... do some dentistry, cut it out of there and replace it.  Again - I doubt this is the problem though.

I think with 40 turns/coil you should get pretty noticable output from that arrangment.

[picmacmillan]

it is hard to see how much metal is in the cold roll laminates ? how thick and so on...if it is mostly ply wood then you arent getting enough metal there for the flux of the magnets, try what dan says and then see if that works, keep asking questions and we will sort it out...sometimes sticking to a known working plan is the best learning tool as when we deviate fro wahtever reason, there is always trouble...the goodthing is you will learn a lot of stuff fast ...good luck on your project...pickster

[ghurd]

Are you getting AC volts?

Flickering ma reading kind of sounds like a bad connection, somewhere.

Test ohms between twisted connections 1 and 3, then 2 and 4, etc.

The readings should be the same.

Hope it is not the magnet polarity.

Bummer there is a problem.  It looks nice.

G-

[kitno455]

hmm, 16 mags, 16 coils, single phase. now, if the magnets alternate NSNS like they should, and you have wired the coils in perfect series, then the norths are canceling out the souths. you have to switch the wires on every other coil. start with a single coil, try adding one coil at a time, the voltage should go up each time (if you can keep the rpms steady)

allan

[PHinker]

It's hard to see exactly but it looks like you're wiring your coils start->end->start->end.  If so, and your magnets are alternating N S N S, and your coils are all wound the same direction (i.e. clockwise or counter-clockwise) then I think you're probably getting cancellation.

You say you're only seeing mA flicker on the multi-meter.  My guess is that you're also seeing little or no voltage, right?  DanB has exactly the right method for 'debugging' your stator.  Do a coil at a time then build up to pairs of coils and make sure you keep adding voltage.  You'll get it sorted.

Very nice construction BTW!

Paul

[Flux]

Can't help feeling that this has all the indications of the meter being set for dc.

If it is it will flick up and down and the faster you spin the less it will move.

Flux

[hiker]

heres a simple test to see if your coils are  wired proper---sence your stator is single phase--hook a 12v batt. or batt charger to the two leads coming out of the stator..hold a magnet in your hand and go over each coil--the mag in your hand should

attract on the first coil- repeal on the secound coil and attract on the third coil

repeal on the fourth coil and so on--get the picture..plus you will find any shorted out coils in this simple test--they will be weaker or not work at all...

when this is all done --and works --you could split the stator in half --for more amp output..just rectife each half then hook in parele............

[Aaron]

DanB, yes I placed the magnets properly and I'm sure its not a short because I was careful to insulate the laminates and I poured a thin layer of resin over them. The thinner the gap the less freely it spins but I thought that was drag from the laminates, is this not the case? I rewired start>start>finish>finish and coil by coil and at 12 coils wired up I'm happy to say that I'm seeing about 8 volts from spinning by hand. Should I connect all the coils this way then be left with two wires which would be my output? Thanks for the help and the furthering of this field

Aaron

[Aaron]

Flux,

Thanks, I think I was reading it wrong but I also rewired and finally saw some output, with 12 coils wired I have about 8v ac by hand.

[Aaron]

hiker, I like this test idea, I'll give it a shot tomorrow @ my shop. I think I just had the coils hooked up wrong.

[Aaron]

Thanks all! Looks like this thing works after all. Gives me a little more courage to take on the dual axial alt that I have going. I'll put up some shots as it gets going. Anyone building these things near Santa Cruz, CA?

[veewee77]

I have a 20-coil, 20-magnet alternator very similar to yours.  my magnets are n-s-n-s-n-s and the coils are cw-ccw-cw-ccw-cw-ccw.  It produces over 40 volts unloaded with a 20" box fan blade on it and it is keeping two T-105 store-brand equivalents charged at a remote cabin. The magnets are only about 7/8"x1/2"x1/8" and I get that much from the alternator! What I would do if I were you, is to unhook all coils from each other, and test the first one (on AC) for volts when you spin it.  Then check the second one, if it is close, then wire those two together so you get double the voltage. then wire the rest of them in the same pattern.  I think you'll find that start-end-end-start-start-end-end-srtart (cw-ccw-cw-ccw) will be the correct way.  If they happen to be laid out in different directions, it won't matter much, but just wire them so that each coil adds voltage instead of taking it away and you will find that thing will likely do about 15V to 20V unloaded. Make sure to measure with AC meter.

Here is a pic of the alternator up close.

Doug

[ghurd]

Doug,

That is a very interesting little mill.

I, for one, would like to see and here more about it.

I am curious about the stator, coil configuration, and output.

Is it a downwind machine?

If it has a tail, I believe the blades will do much better if they are flipped over.

G-

[johnlm]

I also would be interested.  What wire size and how many turns per coil did you use?  Curious that the small fan blades are able to overcome any cogging and loading on the alt when under charge.

Johnlm