williB

I can finally crack the 2A barrier with my DIY Generator..
I hooked it up to an excercise bicycle..lol with a four to one chain drive..!!
If i can find another 2:1 sprocket set , will that be 6:1 or 8:1 final drive ?? 8:1 i think..
Anyway i am now the proud owner of a genny-ciser or exer-gen.. :lol:
Preliminary results are VERY nice.!!
I did a test with a FWB rectifier setup and with no trouble at all i was able to max out my meters 2A scale .. i just thought about the 10 A scale , wow cant wait to try it..
I also tested an 1156 brake light bulb and it was very brite.. :lol:

::edit::
For anyone reading this for the first time i've made a little table of values you could expect for the varibles given..
the coil diameter is 1 inch . the hole is just under 1/2 inch @ 0.480''
if you have any questions please let me know..

Nigel Goodwin

I seem to remember (fairly vaguely) that a 100W bulb is just about sustainable from a bicycle driven generator? - but probably NOT for someone as unfit as me these days :lol:

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williB

:lol: more to come in the next few days .. but i gotta get outside and enjoy this beautiful day..

stevez

Sounds good. Share what you've done when you have time.

You've not mentioned the voltage but keep Nigel's comment in mind. If the total power ouptput at 2 amps is significantly more than a fraction of a horsepower something might be wrong with your measurements. Now, 2 amps at 12 volts makes sense so I am not saying that 2 amps is wrong.

Anyway, I'd be interested in seeing the arrangement if that's possible.

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stevez

audioguru

Soon your generator will provide enough power to supply a motor to propel a bicycle! :lol:
One guy did that with his generator driving a computer fan for propulsion, or maybe it was the other way around, his fan was the generator that drove the motor to propel his bike.

I know, perpetual motion is impossible.

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williB

I believe nigel was talking about the maximum sustainable human output power from a stationary cycle ...yes ?...
the 2 A was not at 12V though as i was seeing what i could put into a resistance of .33 ohms ..
at 2 A i got a voltage of 1.36 V into a measured 0.4 ohms..
V^2/R gives 4.62Watts
but V*I gives only 2.72 Watts
i dont own an AC Ammeter, but i would be interrested to see what is comming out before the diodes..
Pic 2 is a close up of the actual generator..

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Nigel Goodwin

Yes.

How did you measure the 0.4 ohm?.

If you get different values (particularly as wildly different as that), then you've measured wrong somewhere. Certainly the most difficult to measure is the resistance, which is why I asked above. Assuming the voltage and current are measured correctly, then the resistance is 0.68 ohms.

Only 2.72W though is pretty poor?, it's less than you get from a standard bicycle dynamo!.

I wonder how accurate you existing meter is?, as you're not feeding it smooth DC, but essentially double frequency AC that only moves one way from zero - a normal meter isn't going to read that correctly.

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williB

there are currently 6 coils on the generator , two are wound with #17 gage wire , one is #19 gage wire , and the other three are #22 gage..
i have room on there for six more coils.
i have two more coils of the #17 gage wire allready made ,but not on the generater..

williB

total measured resistance minus the meters tip to tip resistance
1.3 -0.9 = 0.4

thats probably why..
you are correct , there was no smoothing whatsoever at the time of the test..
EDIT:ne more thing there are 22 Neodium(sp) Magnets 1/2 " dia X 1/2" long
therefore i can only add 5 more coils for a total of 11.. hooked in series ..

bryan1

Hiya Willi,
Eh mate hooking up those coils in series is probably causing most of your problems. Question have you read up on otherpower and Hugh Piggots book on alternators. All of the alternators I've been studying are hooked up in 3 phase in either star or delta configaration. I'm no guru on this by far but using different diameter wires on you coils could be effecting the flux generated from the magnets and cancelling out most of it. I'm sure if you posted this up in otherpower then they would be a few more people wth greater knowledge to help you out, takin nothing away from this forum mind you. Anyways it's looking good so keep us posted.

Cheers Bryan

P.S. Update on my wind genny project, yesteday I poured the slab for the tilting tower base, so Im a little closer to getting it up and flying

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williB

What i need is another sprocket set , which will give me an 8:1 ratio..
here is why
pedeling really slow gives me a 100HZ on the genny as it is , with very little , to no resistance ( to my pedeling)..
now if i can get 8:1 sprocket ratio , that slow speed pedeling will be 200HZ , and more importantly will hopefully provide just enough resistance to make it fun.. :lol:

Bryan1 i will try the 3 Phase ( star configuration ), i'll have to reposition the coils though..not a big deal..as they mostly are hot glued on there..I'll also need at least one more coil ..totalling nine..
a 150% efficiency increase , over single phase,would be nice,
the delta config. I believe requires to much speed to work effectively..
I added two more coils lately,total 8, and i am charging 5 NiMH batteries in parallel ..
on a side note , as soon as i start cranking the meter jumps right up to an amp. and has been up to 2.2 A at various times..

williB

williB

I've done some conversions and calculated the 100HZ to RPMs..
There are 22 magnets which produce 22 peaks per revolution..
so 100/22 = 4.5 rev/sec .
4.5*60 = 270 RPM
if i double the sprocket ratio this will give me 540 RPM ..
EDIT :: i was wrong here because 22 magnets gives 11cycles per rev..not 22 .. so at this cranking speed i was really getting 545 rpm..

williB

I'm still working on my portable generater..btw..
below is the layout for six x 1.5" coils with 12 x 1/2" dia. magnets..
wired in single phase should output around 24V AC p-p depending upon the speed of rotation and the gage of wire used..
imo 22 to 20 gage would be best , if you go absurdly thin , you get more voltage , BUT the wire resistance will be way too high to do anything useful..

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Klaus

hi Willi,
I'm building a small wind generator with a similar layout as you show. The difference being that my 6 ( pancake) coil stacks are arranged so that they almost touch each other. They are spaced so that when a magnet's leading edge just enters a coil's outer diameter its trailing edge just leaves the centre diameter of the previous coil, I read somewhere that this spacing is the most efficient for PM poles.

I'm also using two sets of pancake coils per coil assembly, second is offset to the first The magnet rotors have 10 magnets on each side. It all gets quite complicated mechanically as there are 3 PM rotors (40 magnets total - centre one has magnets on both sides) and two coil disks placed between the rotors with minimal air gap. The pancake coil disks assemblies, holding 2x6 offset coils, are just 6mm thick.

I never bothered about the star delta business since the end result is DC anyway. It is far easier to just connect the coils in series with such a thin assembly.
So, each set of 6 coils is connected in series for a total of 96 turns and the two ends of each coil bank go to a bridge rectifier which should give me a fairly low DC ripple at the paralleled DC ends of the 4 bridges.
The coil wire size is 1.1mm, whatever gauge that corresponds to, I used what I had with a compromise of low resistance and the ability to cram turns into flat coils.

I wish I could post test results of this arrangement but I'm still getting ready to cast the aluminium endcaps which will hold the bearings after machining them. I would be happy to get around 200W from a 1m diameter prop.

Klaus

williB

Klaus,
I shifted the coils around in a tighter pattern , keeping the same number and spaceing of magnets..
This sure gets complicated !! , because , for my case anyway , i cant just add two coils and expect it to work ..as you can see , its not gonna work..
i'm gonna try a different number of magnets.. :lol: i'll get back to ya...
1.1mm wire is 0.043 " its between 17 & 18 Gage , good thick wire..

Brayn you were correct.. ops:
i did a scope test of individual coils in the generator under load..
the 17 Gage wire turned out a perfect sine wave , while the coils of the thinner wire , were somewhat distorted..
I guess ya cant mix coil wire diameter in the same generator, who would have thought ?? :wink:

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