low output new dual axial alternator

[Aaron]

hello collective brain,

i made this quite a few months ago, got really busy/lost interest/got frustrated and now i'm ready to deal again. i got the magnets from windstuffnow, they are the 1/4'' thick wedge shaped kind. the stator on the side consists of 80 turns of # 16 wire. i remade it cause i figured the coils were too far apart. both stators are three phase and were able to be wired in star or delta. they both only put out a few volts (maybe 10 max) when being spun by hand. i checked all the connections and the magnets are placed correctly (north, south, etc). the other stator (shown on the alternator) has 40 turns of # 11. am i missing something assuming i didn't botch up any wiring?

another semi-related question/comment is about this hand crank generator i came across in my seemingly endless obsession. it puts out 50 volts if you really get it going. how can this LITTLE dc motor do the same as my AMETEK tape drive motor, or does it?. i mean can it really be possible that this thing could charge 12 volt batteries? once again.....what am i missing?

[windstuffnow]

  It's quite possible something is wrong with the wiring, although, the 40 turn stator will need about 180 rpm to make 12 volts so you may not be spinning it quite that fast by hand.   Using #11 wire when it does start charging will definately produce some amps !!  What size prop are you going to drive it with?  What is the thickness of the stator?

.

[hiker]

i agree with ed..

sounds like you need more turns if your trying  to get 12v by hand..

toss a prop on there and let her fly..should work fine the way it is..

[Tallwind82]

Hi Aaron

Regarding your little hand crank generator:

Higher voltage does not necessarily mean there is more power. At any given rpm you can get a wide range of voltage, depending on:

(1)the strength of the magnets

(2)number of turns per coil

(3)number of coils

(4)whether the coils are wired in series or parallel

(5)efficiency of the generator

Volts x Amps = Watts

Your little hand crank generator may put out relatively high voltage, but the current is fairly low. Yes you could probably charge a 12volt battery with it, but it would take a LOOOOOOOOOOOOOOONG time! You only get as much power out of it as you put into it minus the inefficiency factor (losses due to friction).

Voltage can be compared to the speed of water through a pipe. A small pipe can't compete with a large pipe if the speed is the same, because the volume (current or amps) is different.

[Aaron]

thanks for the imput, much appreciated. i understand much more about voltage/current. i do not yet have a prop. the thickness of the stator is around 9/16''. i'm wondering... 1.if i want more volts at lower rpms it sounds like i need to fit in as many turns as possible, it looks like i could fit a few more. 2. what if i used a slightly thinner wire, fit in as many coils as possible and wired it single phase, would this help increase power? a year or so ago i made a smaller machine with smaller magnets and this seems to put out 12 volts at lower rpms.

[Flux]

What volts did you measure? ac phase , ac line or dc after rectifying.

Remember that if it was 10v ac line( between a pair of leads) then it would be more than enough to charge a 12v battery when rectified.

Your stator is very thick for thin magnets. 3/8" thick would have been better.

you still have space left to use more turns of the same wire, you can go to thinner wire if you need to go even slower.

You give no indication of the size or type of prop you intend to use, it is quite likely that you may be slow enough already, I am not sure how fast you can hand crank it but it probably is not above 250 rpm.

The very low speeds mentioned here are for large props, you won't be able to use anything above 6 or 7 ft so a cut in of 200rpm is about the slowest you would hope to use and 250 to 300 would still be within reason.

Flux

[Flux]

I should have added  Avoid single phase like the plague it has no advantages whatsoever.

You can get any volts you want at any speed with greater efficiency and less vibration with 3 phase.

Flux

[nothing to lose]

"Remember that if it was 10v ac line( between a pair of leads) then it would be more than enough to charge a 12v battery when rectified."

Got a question for a little motor mill I put up. Maybe about the same as a treadmill motor?

I get well above 15-20Vac open volts when it's turning, after connecting to a bridge rectifier I drop to about half the volts DC , nothing but the meter connected still. Is the mill just putting out so little watts that the bridge itself is eating the volts? I do have the AC and DC wires on the bridge correct also.

 The mill has too big a blade and other problems I know of anyway, so it does not do well.  But I keep seeing mentioned  the volts going up when rectified AC to DC, mine are going down with this mill?? It does run a 12V computer fan slowly if it catches the wind.

I'll be taking it down in a couple days to put a different one up in same spot anyway and will change blades then too.

[Aaron]

Remember that if it was 10v ac line( between a pair of leads) then it would be more than enough to charge a 12v battery when rectified.

Flux,

actually i didn't know this. i was measuring ac line, right off the alternator itself. i wasn't sure but thinking about using a 6' prop. another question... do the spaces i have between the coils (on the disconnected stator pictured) affect performance or does it matter?

thanks,

aaron

[Flux]

Are you sure it is ac? Treadmill motors are dc. Many meters will read something on the ac range when fed with dc, but what depends on the type of meter.

If it is really ac then after the rectifier with no load you should see about 90% of the reading on a dc meter. If not you have a rectifier problem, could be connections, exceeding the rectifier maximum voltage or faulty diodes.

If it runs a computer fan I suspect it is already dc. Try your meter on the dc range and see if it reads, if it doesn't then it will be ac.

Flux

[Flux]

It will probably be ok on a 6 ft prop as it is.

The unused space between the coils only means that you are not using the thickest wire possible for the number of turns. This will reduce the alternator maximum output current but whether it has any ill effects in the wind depends on the matching between the prop and the alternator. If you have too much magnet then the higher resistance may keep you from stalling and give you more output as long as you don't cook it.

I prefer to use all the space even if it means adding resistance to the line, where the heat is not a problem.

Flux

[windstuffnow]

 aaron,  I'm thinking the resistance in of your stator may be a bit low for a 6ft prop.   I'm just guessing here but it should do a bit better than my 500 watt kit.   You might consider going to a 7 or even a faster running 8ft blade... My gut feeling is the 6ft blade may work ok in lower winds but the alternator will load the prop to much in mid range wind conditions and stay in a stalled (poor output) range until the winds can match or overpower the alternator.  Maybe an 8ft prop with a TSR of around 7 to 8 would do nicely with it.  Some food for thought...

.

[willib]

Nice work there Aaron,

Assuming that youve wired it correctly and the center of your coils match the center of your magnets(its hard to tell from the pic , the top left stator must be closer to the  camera than the rotor.)

And assuming your air gap isnt to large , that baby should work like a charm..

Your old 16 magnet rotor can still be used but your old 16 coil stator is a gonner i'm afraid

here's why

For three phase the number of coils must divisible by three and end up with a whole number  16/3 = 5.33.. not good..

To make it single phase wont work either , because for single phase each pair of poles must pass over each coil at the same time , to do  this on that stator ,you would need to put a North pole and a south pole right next to each other, also not good. it might work that way , but making another rotor just to salvage a bad stator dosnt seem like a good way to spend your time.

But on the bright side the 16 magnet rotor is still useable.

[nothing to lose]

Not sure what to figure this one as now.

I get a higher reading on AC than DC checked direct without bridge and both read.

Normally reversing the leads on the meter will read a negative DC, like if I connect black to positive it still reads the same volts but with a minus sign, this motor does not.

I get about half the volts after the bridge for DC.

 Also my computer fan will not run on it direct, even reversing the leads (DC polarity?) it sill does not run. I know the fan only runs on correct polarity but not when reversed. Same fan is running now on the bridge rectifier just fine. No battery, just direct from the mill using the bridge rectifier.

This is a DC motor, similar to a treadmill motor, might even be from a treadmill?

Gonna take it down to put another up, will look for specs then.

I had 2 of these, 2 large ceramics inside and brushes, the other is not here, it had a magnet loose in it so I opened it up, still at other house.

[nothing to lose]

"If it runs a computer fan I suspect it is already dc"

Sorry, I meant it runs the fan after the rectifier. It does not run the fan without one.

[nothing to lose]

Well, never figured out what was wrong, but it is a tread mill type and output is DC, NOW.

Something funny was going on somewhere. Maybe bad wires or stuck brush, who knows? I am getting more power now and DC for certain also. And the meter reads volts as negatives if I reverse polarity too as it should. Did not do that before either.

I thumped it around a bit while changing blades, changed cord, other work too.

[evilgenius]

this is probably too late but o-well

just looking at your setup i noticed

you didnt incorporate an iron mass

of somesort inside each coil....

magnetic concentration is the key to

rule the world.