Meter readings on small generator

[chazsql]

When I connect my meter leads, correctly, i get little or no volts.  I haven't seen  much 1 volt.  When I connect my negative lead to the positive side of my rectifier, I get about -4 volts or a little over, spinning it by hand.  I'm spinning the turbine on a test stand and it's a very small turbine with 6 coils, 2 strands of #18 wire, three phase, 1.5" x .75" x .25" magnets.  Two saw blades were used as the backing for each rotor.  I wanted to go through the process, once, before I used more expensive components.  Can anyone give me an idea of what I've done wrong or is the alternator just too small?  Why should the readings be so different?

[ibeweagle]

first see if you are getting any wild ac from the turbine if so I suspect the rectifier problem or a short in one of the diodes cheers Mike ibeweagle@hotmail.com

[wooferhound]

Are you sure that your meter is working properly ?

you are set to the correct AC or DC mode ?

if it is an AC voltage then is the frequency up high enough to read correctly ?

[wpowokal]

As Woof said, but why are you connecting the negative lead of your meter to the positive side of the rectifier, assuming your meter is selected to DC. And where are you putting the positive lead?

allan

[hiker]

so is it a 8and 6 setup?

you need 8 mags per rotor if its a dual rotor or 8 mags on one rotor..

six coils..two per phase..

heres my 9 and 12 sawblade rotor mill..

made it a few years back--works great on my motorhome-ceramic mags with small neoes

glued on top of the ceramic mags..

just a blast from the past--works for me!!

have plans to upgrade-hmm..

   http://www.fieldlines.com/images/scimages/1236/test_stand_mill_3

[ghurd]

"6 coils, 2 strands of #18 wire... 1.5" x .75" x .25" magnets"

It sounds like there is not enough room for the coils (stator and air gap too thick),

or not enough turns per coil (wire too thick).

Two-in-hand #18 (equivalent of #15) sounds like enough turns per coil can not fit in the space it has to fit into.

My guess is it needs something on the order of 130 turns per coil fitting into a 3/8" thick stator.

G-

[chazsql]

I swapped the positive and negative meter leads, out of curiosity.  I got higher numbers, but, negative, of course.

[chazsql]

Yes, 6 coils and two rotors with 8 magnets each.

[chazsql]

But, why would my readings be so different?  If I swapped meter leads, shouldn't only the polarity change?

[ghurd]

It should not be different, even with a cheap meter.

Best guess is the RPM were different.

You are operating at the fringe of conducting through the diodes.

It will not take much change in RPM to change the open voltage output quite a bit.

Might get more accurate readings testing AC between 2 phases before the diodes,

or adding a capacitor on the DC output wires to test DC voltage.

G-

[chazsql]

OK.  Thanks

[chazsql]

Thanks.  BTW, I like your videos, on YouTube.

[chazsql]

How many saw blades dis you use for each rotor?  I only used 2.  I may need to add more.