12 V -0 amps alternator

[Gunson]

Hello enthusiasts!

I thought I was "finished" with my first functioning alternator. I now know how to measure current and the readings ain't good.

When I connect, through rectifiers, to car battery(tried different batteries,state of charge) I have, at 156 RPM's, 12 V and about 100 mA...

When I put a 12 V, 4,6 A (measured 0,3Ohms in cold state) there is 0,33V and 1A through the connection.

The magnets: 12x2 N42,  1" diameter, ~2/5" hight(25mm x 7mm). Theoretical lift power

12 Kg.

The coils: are 9, 100 windings with approx. AWG 21 or 0,75mm diameter( 0,44mm2)

So there are three phase connected in star. Three "starts together and three outputs.

I also made another generator 12V -0A!

I've uploaded some photos of the making.

Where'sthe problem? There is too big gap between the magnets? I thought that was necessary to prevent a coil leg to get north and south pole at the same time.

The magnet discs are homemade and aren't excactly round. A couple of magnets are up in the "roof" of the coils. And the two rotors are not exact mirrors of each other, but very close.

What could be the biggest disturbance? The coils placement or magnetism on the wrong spots to get the result  0, or close to, 0 Amps?

Thankful for any thoughts about this subject. MAny people must have had the same problem but I couldn't find the right info I need on this discussion board.

Gunson

big pic

all photos in a post need to be under 150kb and less than 640 x 480 pixels. thank you.
Kurt

[Flux]

I don't follow some of this.

"When I connect, through rectifiers, to car battery(tried different batteries,state of charge) I have, at 156 RPM's, 12 V and about 100 mA.."

The volts will be battery volts so that seems ok. If you have 100mA then you are just on the point of cut in at 156 rpm. if you drive it faster the current should rise.

"When I put a 12 V, 4,6 A (measured 0,3Ohms in cold state) there is 0,33V and 1A through the connection. "

No idea what that means.

Your magnets are small so it seems fairly likely that your cut in could be at something like 156 rpm. If you drive it faster it should start to produce current.

I can't see that you have done anything wrong, it looks ok. Disconnect the battery and check that you are getting about 12v at 156 rpm. If so the 100mA is perfectly ok. Double the speed and you should get a few amps.

I assume you can only drive it at 156 rpm. You should be able to hand crank it faster than that and feel the load come on as you get past cut in.

Flux

[ghurd]

"When I put a 12 V, 4,6 A (measured 0,3Ohms in cold state) there is 0,33V and 1A through the connection."

Are you trying to test Current and Voltage of a 0.3 Ohm load connection at the same time?

It sounds like improper measuring procedures.

G-

[Gunson]

Thanks Flux

I was aware that there is no connection before the battery starts to charge but I didn't know the current "started from scratch" at that level. Also, there has been other problems before so this is my first accurate reading.

300 RPMs - ~3 A

"When I put a 12 V, 4,6 A (measured 0,3Ohms in cold state) there is 0,33V and 1A through the connection. ""

    ---This is a car light, forgot some words in that sentence.

Do you also know how it works with two magnet poles in the same coil leg, due to small space between magnets?

Have been looking around several hundered hours for info but never seen info about that subject. Hard to find "induction schools" on the net.

thanks again

Gunson

[Gunson]

Hello Ghurd

The shunt regulator works fine /:~)

It's a car light.

I measure Voltage through the connection and current with, what you call it, amp-claw pherhaps.

Gunson

  Sweden

[Flux]

If you have cut in at 150 something rpm and 3 A at 300rpm all seems well.

With small magnets you will need small blades and they will be fast.

For axial machines with the 12 magnet 9 coil layout the best results seem to be with the space between magnets being roughly the same size as the magnets.

Forget all about coil sides and legs, you need holes in the coils about magnet size ( a little smaller doesn't hurt) and generally the best shape for the coils is the same as the magnets, round in your case but your coils look perfectly ok.

You won't find much theory about these things in many places they are peculiar to small wind power and have mostly been developed empirically.

With your small magnets you need lots of turns of thin wire so your output will be limited and it will need good speed to give much out but it should be a good machine to learn from . If you can get some suitable blades I am sure it will work fine.

Flux

[ghurd]

Happy it works!

The car light is nearly a dead short under these "cold" conditions.

The light is sucking out all the amps before any voltage can build up.

Try to get the alternator spinning faster, and measure current into the battery.

G-

[defed]

so, up until cut in, you are making no amps...then, once you reach cut in, the amps increase as rpm increases while voltage remains held by the battery?

once you reach cut in, does the alternator keep getting harder to turn as the amps increase or does the resistance remain essentially the same once it starts charging (while amps increase with rpm)?

[defed]

i should have worded this a bit differently...it was a related question of my own about how the alternator is supposed to work, not a question to the original poster about his performance.

[ghurd]

A bit oversimplified,

As the Power (amps x volts) output increases, yes.

"once you reach cut in, does the alternator keep getting harder to turn as the amps increase..."

Yes.

"...or does the resistance remain essentially the same once it starts charging (while amps increase with rpm)?"

Yes.  Resistance is Ohms, and the Ohms are fixed.

The required Torque increases as the output power increases.

If it did not, then a high speed 1/10 HP motor could turn a alternator making 1,000W,

And that Ain't gonna happen.

It is this relationship not understood by the general population that scammers prey on to sell crap about over unity.

G-

[Gunson]

Well it's working now

What I learned from your excellent and fast(!) answers and experimenting is that current does have a very rapid curve and in this case doesn't get interesting before the alternator produces about 24V. I wonder how the battery can handle 36 V...?

[ghurd]

The same current that keeps the voltage low with 1A of a near short circuit,

keeps the voltage below 36V.

The higher voltages of the alternator are sort of converted into more charging amps.

I believe the 24V battery will stay below 35V until all the water is boiled out, and the batteries are ruined.

That's what the Fabulous Ghurd Shunt Regulator shunt regulator does... It keeps the battery voltage low enough not to ruin itself from over voltage.



G-

[defed]

thanks Ghurd.  when i said 'does resistance remain the same' i did mean the amount of force needed to turn the alternator, not the ACTUAL resistance.  but you answered both, obviously you deal with enough newbs.

it makes sense that it should get harder and harder to turn as output increases, i just wanted to make sure.  i know that you can't get something from nothing.

i'll have a cpl questions about your controller soon, i've read so many threads about it, i should know everything about it, but sometimes too much info gets confusing.

 

[ghurd]

"Ghurd will be on holiday vacation until 8-27-09"

G-

[Gunson]

Hi ghurd

what Imeant was it's a 12V system and the amps are not interesting until the generator is around 24V. So the battery will boil and dry out when it's receiving double or even triple voltage? thatäs not splendid at all...

thanks for all the info

[Flux]

You are looking at open circuit volts. The alternator has resistance and when you connect to a 12v battery the battery holds the output voltage to a little over 12v.

If the open circuit voltage is 24v and for example the resistance of the alternator was 2 ohms then you would have 12v ( 24-12) driving current through 2 ohms and it would produce 6A.

If you raise the speed to get 36v open circuit then you will have 24 ( 36-12)V pushing current through 2 ohms and will have 12A.

Until the battery is charged all the current will go into charging it and the voltage will stay below 14v. When fully charged then the current goes into heat and gas and that is when the voltage can rise and you need a charge controller to limit it.

Flux

[Gunson]

Thanks Flux! I've been looking for that explanation for a long while...

I will experiment in what magnet placement the highest voltage is achieved.

If it's not a problem with two magnet poles in same coil leg, this gets much easier.

Gunson

[freejuice]

I love this thread!

 It really explains the interaction of how the generator meets "resistance" (harder or easier to turn) when it is all hooked up, supplying power to the batteries...wonderful

[opo]

Me too!

Thanks guys for the patience teaching effort.

Salud!

Octavio