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#Post#: 466--------------------------------------------------
Re: Seagull DIY Discussion
By: lynx wind Date: September 29, 2013, 5:44 pm
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@Idissing
That seems like very low voltage. Are the coils in series? My
coils are packed tightly with turns of 20awg. I don't know how
many turns but the total resistance is 5.8-6.0 ohms. Seems like
there were 300+ turns. I look for my notes.
I see 12 volt deep cycle battery charging in 9 mph winds. My
gap is maybe 1/16" or less.
If you want charging in lower winds you would need to use 22 awg
or finer, but the resistance goes up. I think 20 awg is a nice
compromise because there isn't much power below 10 mph wind
anyway.
If you can't fly a kite, there isn't much power in the wind.
#Post#: 468--------------------------------------------------
Re: Seagull DIY Discussion
By: ldissing Date: September 29, 2013, 9:15 pm
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Yes, the coils are in series. I will make new coils with as
much copper as will fit into the space and see what happens. I
thought the ohms was pretty low, but hoped for the best based on
the number of turns, etc.
I had a lot of space around the coils, so I could have doubled
the copper, but I'm afraid, that since I used 3/4" coils that I
need 1/2" magnets to get full effect.
If I can get 7.5 ohms or better I will do the voltage doubler as
did crazyguy. But, 300 RPM was pretty good, if I calculated
that correctly....did I?
#Post#: 469--------------------------------------------------
Re: Seagull DIY Discussion
By: lynx wind Date: September 29, 2013, 9:52 pm
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Yes, cram as much copper as you can get. Try not to go much
over 9 ohms because the resistance starts hurting top end power.
22 awg might be better than 20 awg just for earlier cutin. If
I made another Seagull 75 I would definitely go with 22 awg.
Don't worry so much about the way the magnets cover the coil
legs. It's the movement of the poles across that gives the
spikes. And with the single phase, the flux lines aren't what
you might think. Roughly you want the magnet as wide as the
coil leg. Crossing the apex of the coil a little isn't a big
deal.
You don't want to cutin too early so I wouldn't recommend a
voltage doubler. It wont increase watts, just stall the turbine
below TSR1. Your 300 rpm is correct, but will calm down if your
alternator has more turns. A better cutin speed is about
150-180 rpm. Top end will be 800 rpm.
Hope this helps
#Post#: 473--------------------------------------------------
Re: Seagull DIY Discussion
By: sut Date: September 30, 2013, 9:55 am
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Hi all I have a couple of questions ! 1. does it matter which
way this vawt turns ? because if you place the magnet plate on 1
side it will turn to the left but if you flip the rotor over
and place the magnet plate on opposite side it will turn the
opposite way.( and yes I mean that the mag plate is always on
bottom above the stator) 2. does it matter which wire coming off
the coil is positive (inner or outer )
#Post#: 474--------------------------------------------------
Re: Seagull DIY Discussion
By: Otis Date: September 30, 2013, 10:51 am
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I beleve you can have them spin clockwise or counter clokwise.i
prefer the counter clockwise but if i had two of these id
probably put them spinning in opposite directions. Until the
rectifier diodes its ac, so it doesnt have a dc type plus or
minus.after the rectifyer you can check polarity with a
multimeter. Hope it helps.
#Post#: 475--------------------------------------------------
Re: Seagull DIY Discussion
By: Otis Date: September 30, 2013, 10:53 am
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Wait a sec. Marcus has said the blades are not symetric, so you
may want to be careful of high camber in or out too.
#Post#: 477--------------------------------------------------
Re: Seagull DIY Discussion
By: ldissing Date: September 30, 2013, 2:32 pm
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Ya know...I bet I messed up and put one of the coils in the
opposite direction. At 300 rpm, I should have seen some pretty
good voltages coming from it and didn't. If I did goof that
up....I will kick myself.
I did double check, but maybe a triple check would have been
better.
@Lynx....
What is the highest voltage you've seen with your 20 gauge wire
VAWT?
Leroy
#Post#: 479--------------------------------------------------
Re: Seagull DIY Discussion
By: lynx wind Date: September 30, 2013, 3:51 pm
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I will respond to some of the very good questions and
observations.
It doesn't matter which direction you set up the VAWT.
Doesn't matter which way the magnets pass the coils.
The Seagull is designed for symmetric NACA 0020 blades so there
is no inside outside. The Gulls are more of a 2420 blade that I
designed.
Youch...It is so easy to reverse a coil. Once you experience
that you will never do it again...trust me. When I wind coils I
follow a convention and am very careful to connect start to end
to start to end... I double and triple check things before
casting stators. I also test with a continuity tester to make
sure all connections are good. I also check each coil's
resistance separately and then verify the total adds up from the
individual coils.
The highest voltage I have ever seen was 172 volts. But
normally I would never run a turbine unloaded. The highest you
might see with the Seagull would be about 50 volts.
Another way to test a stator is to hook up the AC output to two
diodes reverse polarity. Turn the rotor slowly and you will see
two distinct pulses as the voltage goes through its sine wave.
A bright LED will indicate about 2.5-3.0 volts.
#Post#: 482--------------------------------------------------
Re: Seagull DIY Discussion
By: sut Date: September 30, 2013, 5:46 pm
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Great thx for all the info.! I am getting close to starting
this project all I need is time (then wind )
#Post#: 495--------------------------------------------------
Re: Seagull DIY Discussion
By: ldissing Date: October 3, 2013, 6:07 pm
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Okay, I did some surgery on the stators and chipped out some of
the resin so I could get to the output wires. I do not believe
that I hooked up the input to output incorrectly, but I do
believe that I flipped one of the coils, so it is fighting the
other two.
I put my lathe on 300 RPM and the output looked the same (magnet
side on the lathe spindle).
Then, I cut one of the output wires going to the next coil, so I
could measure a single coil. I was able to get 2.5V DC at 300
RMP which means the AC is even higher, because of the diodes.
So I need to add some more copper to the coils and I think I
should be good to go. If I could double the copper, maybe I can
get 5V / coil which would be nice, but I'd prefer it to be at
least 3 ohms per coil or 7.5V /coil (or more) at 300RPM. Don't
know that I have enough space for that with this 18 gauge wire.
I have some 20 gauge, but I'm afraid it is not enough wire and
some 24 gauge (a bunch), but no 22 gauge wire. Seems like
6ohms would be about perfect.
Leroy
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