2' x 2' Lenz question

[bug bit]

I have built an 8inch, 12 pole 9 coil dual rotor. 1x1 1/2x1/4 n35 neo. 115 turns of #17awg, the coils are 1/2 inch thick with a 1/2 leg, the inside of the coil is the size of the magnet. The coils weigh 6.5oz each. It is turning about 96rpm when it hits 13 volts open (all the faster my house fan will spin it) . When I plug in my 7ah battry it drops the rpm to about 70. The air gap (magnet to magnet) is 3/4" right now. I know that is a lot of air between magnets, I am working on that. Am I in the ballpark for for a Lenz? There are a couple of pictures in my files, more when I get batteries in the camera.

Brian

[Norm]

I think you need something more powerful to spin

it....even with a handcrank you can spin it

faster than that.

13 volts open don't mean much....Unless the battery

is a 6volt....then what is the voltage when you

hook it up to the battery?

  Need more pictures...don't really understand

what you mean by the 2'x 2' Lenz  part.

    ( :>) Norm.

[Norm]

Excuse me I see what you mean now you're blowing

air on the 2'x2' Lenz...is that the latest type

of Lenz?

Using a fan doesn't give it a fair test outside

in a 10mph wind will give you a better idea...

with the battery plugged in and hooked thru a

digital multi-meter and see how many milliamps

or amps its charging the battery.

          ( :>) Norm

[bug bit]

It is 2 foot diameter by 2 foot tall. I know it isn't a fair test, but my apartment is all i have right now and the weather isn't cooperating.

[alancorey]

I'm no expert, but I don't usually let that stop me from blundering in...

I'd say you're in the ballpark.  Without knowing beans about the particulars of axial flux generators, I'd say that if you connect the battery and it slows down the Lenz, that's because you're charging the battery.  Looking at the current flowing would confirm that.

The question I have is what happens next.  Does the generator continue to put out enough to charge at 70 rpm?  Or does it cut out, the Lenz speeds back up, then the generator cuts back in and it all slows down again?  Probably not.

Another simple thing you could try is hooking up a small 12 volt light bulb while you're connected and spinning along at 70 rpm.  That should slow it down even more.

I think you're in the ballpark, or on the edge of it.  The problem is that if you go to a larger diameter Lenz the rpms will be lower and your generator may not cut in at all.  Your fan is probably marginal.  I'd rig it up for travelling and take it all outdoors for more testing, on a day with good winds forcast.  Measuring current into an SLA may not be all that great a method of measuring current either.  The ones I've fiddled with seem to have a maximum current they'll charge at, which will mess up your readings if you might otherwise get above that.

  Alan