Lenz2 low output

[velacreations]

I bought magnets and supplies to build a Lenz2 several years ago.  I bought the magnets from Ed.  I finally got around to building it.

But, the cut in speed is not impressive, we have been getting some heavy winds, but it doesn't seem to be charging.  I don't know the exact wind speed, but today, I estimated it at 15 mph or a bit more, and it was outputting about 10 volts. 

The air gap came out a bit bigger than I hoped, mainly because of the stator thickness (5/8"), and then a 1/8" gap on either side. Could my cut in speed be due to the gap?  Or maybe the blades are too "dirty" to effectively get up speed?

Here is a set of photos to see how we put it together:
http://www.flickr.com/photos/velacreations/sets/72157633881302047

Here are the blades:
http://www.flickr.com/photos/velacreations/8926783583/in/set-72157633881302047

And here is the PMA:
http://www.flickr.com/photos/velacreations/8927353024/in/set-72157633881302047

Do you know of a simple way to estimate/measure rpm?

[Bruce S]

Ed is still around.
You might pop over to his website and send him a message.
He's one of the best in this area!
Below is a link.

http://www.windstuffnow.com/main/vawt.htm

[velacreations]

Ed is still around.
You might pop over to his website and send him a message.
He's one of the best in this area!
Below is a link.

http://www.windstuffnow.com/main/vawt.htm

Yeah, I did, I just wanted to get other opinions, too.

[bob g]

estimating windspeeds can get you into trouble, generally the windspeed is something significantly less that what one estimates.

then there is the issue of just how fast it is at the turbine?

seems to me that if you are using one of Ed's designs, you might want to deal directly with him to sort it out, any other advice is likely to be of questionable value in my opinion... in other words why not go straight to the expert rather than deal with input from arm chair amateurs that have never built one of that type,  or even from those that are relative experts in windpower that have still not built one of that design?

without knowing exactly what the windspeed is, as seen by the turbine, and without knowing more of the specifics on how you built and connected your stator, and a plethora of other questions, it is doubtful you are going to get much useful input or diagnostics

my opinion  only,  and it is worth maybe half what you paid for it.

good luck

bob g

[velacreations]

estimating windspeeds can get you into trouble, generally the windspeed is something significantly less that what one estimates.

then there is the issue of just how fast it is at the turbine?

yes, this is true, but it was during a storm, and that wind was blowing decent.  Enough to bend trees.  I understand what you mean about the exact speed, but I can tell you that it should have been producing 10 volts, in my opinion.

seems to me that if you are using one of Ed's designs, you might want to deal directly with him to sort it out, any other advice is likely to be of questionable value in my opinion... in other words why not go straight to the expert rather than deal with input from arm chair amateurs that have never built one of that type,  or even from those that are relative experts in windpower that have still not built one of that design?

I am speaking with him, but I am also seeing if anyone here has suggestions or possible ideas, like with the gap between the magnets, etc.

without knowing exactly what the windspeed is, as seen by the turbine, and without knowing more of the specifics on how you built and connected your stator, and a plethora of other questions, it is doubtful you are going to get much useful input or diagnostics

what specifics would you like?  The stator is 9 coils with 70 turns of 14 gauge wire.  The magnets 12 per disc (10" disc), and made from Ed's wedge magnets.

I really need a way to estimate/measure rpm to get an idea of what is going on.  My initial thoughts are that the gap is too large and that maybe I have too much turbulence on the blades (Ed agreed with this).

[Flux]

I don't have enough knowledge of the design to really help. I assume you should know the cut in speed of the alternator and that can easily be checked.

You say the gap is big but you don't say how big. I have a feeling that this may be a significant factor at 7/8". Those wedge magnets of Ed's are fairly thin as far as I can remember and I suspect yout gap flux is not very high.

Unless you get some advice directly from Ed, you could try reducing the 1/8 gap on either side to 1/16 for trial and if that makes a significant difference then the gap is likely your trouble.

I know nothing about the turbine but you should be able to get the cut in speed from Ed and you can measure that on the alternator alone by hand cranking or you may be able to do it on the turbine with an optical tacho.

If the cut in speed is in the right order then most likely you have turbulent winds, on poor sites you can nearly blow trees over and still get little power. If it is a clean exposed site and you have that sort of wind it ought to be doing something.

Flux

[velacreations]

yeah, I really need a way to measure rpm.  I don't have anything at the moment.

I think 7/8" is probably too much, too.  I will see if I can trim that down a bit.  If not, I guess I could replace the magnet discs with ones with bigger magnets (I have a set of the bigger ones)

[dnix71]

http://www.ebay.com/itm/Digital-Photo-Laser-Tachometer-Non-Contact-Tach-RPM-Tester-/281014954775?pt=LH_DefaultDomain_0&hash=item416dcbeb17

$14 shipped from eBay. Uses reflective tape. Useful for bench testing, not from a high place.

[velacreations]

thanks! that's exactly what I need!

[tecker]

Bicycle speedometer can be permanently installed

[bob g]

are the coils connected in star(wye) or delta?
is it possible  you have a phase coil connected backwards?

if each phase coil group is individually rectified, then maybe the aforementioned does not apply?

just a couple of things that would reduce output that come to mind.

may not be the problem, but thought i would toss them out there anyway.


bob g

[velacreations]

they are wired in Star, I believe.  That's where one set of ends are all connected together, right?

yes, each leg is individually rectified.  I don't think I have anything backwards, I certainly checked a number of times before adding resin, but you never know.

[Neil]

when you short it out , is it hard to turn?

[velacreations]

when you short it out , is it hard to turn?

yes, very hard to turn.  I have a stop switch installed, and I have used it.  It definitely works, though in a high wind, it will still spin slowly.

But, by hand, there is a huge difference between shorted and open

[GoVertical]

Hi, what is the internal resistance of your stator?  Can you test your PMA using a hand crank using a 12 battery as a load?

[velacreations]

ok, an update on this.

Yesterday, we took the generator down and changed some things. 

First, we put on a bike speedometer and tested the rpm at specific voltage outputs.  For 13 v, it was over 220 rpm.  So we reduced the gap as much as possible, I think it's just under 3/4".  We hit 13 volts at ~180 rpm, now.

We adjusted the blades by removing all the metal hex head screws and replacing them with a low profile screw.  Also, we cut off the extra metal on the ends of the blades, so now they are flush with the end piece.

We put everything back together, but we haven't had much wind.  We had a little wind in the afternoon, and the generator hit 10 volts very easily, but I never saw it over 12 volts.  The wind, however, was considerably less than when it was hitting 10 volts before, so I think we've improved.

I still think the blades are limiting things, maybe they need to be a bit bigger and/or smaller diameter for faster speeds.  Alternatively, I am researching different blade styles for a faster VAWT blade.  Does anyone have any ideas?

The cut in speed of the motor is still considerably higher than Ed's, so I'm thinking my stator is just too thick.  I can change out my magnet discs and put on the Forcefield 1" by 2" rectangle magnets, but I'd like to try and make what I have work.

[Flux]

Glad you are making progress. I suspect your alternator is still rather fast vor a VAWT but it might be worth waiting for a bit more wind.

With the gap as small as you can get it, there is not a lot more you can do with the present stator except to try some form of boost circuit, assuming it is already star connected.

Flux

[velacreations]

Glad you are making progress. I suspect your alternator is still rather fast vor a VAWT but it might be worth waiting for a bit more wind.

With the gap as small as you can get it, there is not a lot more you can do with the present stator except to try some form of boost circuit, assuming it is already star connected.

Flux

yeah, I agree.  It is performing better, still not at the level I need, tho.

Basically, here are my options:
1. increase the speed of the current wings
2. change wings to faster design
3. change magnet rotors to larger magnets
4. make a different stator

I'm kinda maxed out on #1, though I might be able to think of a few more things to increase their speed marginally.

I don't really know enough about VAWTs to even look at #2, but if anyone has a faster wing design, I'd like to look at it.

#3 is easy enough (I have the magnets), just need to get 2 more discs made.

#4 is costly, cause I am out of resign, I have a lot of copper, but it is all #14, and my coil jig is preset to 1/2" thick.

Alternatively, I change this whole thing to a HAWT, but I that will require a lot of time and money and effort, and I'm not really willing to do that, at this point.

[GoVertical]

Hi, VAWTs are slow. You need to see cutin at 50 RPM or lower. Increasing the magnets size and reducing the air gap helps. Because your PMA is air core you should be using a lift style blade.   The other alternative is to add a transmission.

[velacreations]

well, Ed's PMA was cutting in around 120 or so, which is still lower than mine (I am using larger wire), but seemed to be possible.

What sort of lift style blade do you recommend?

[electrondady1]

ed did a lot of development work on his design that's why people all around the world have built them.
if your using larger dia wire you won't get the number of turns in the same space. . you won't be able to generate the same voltage as ed does at the same rpm.
you should have used the same dia of wire as ed does and if possible the same no. of turns.

 in order to salvage what yo have  you need to overdrive your alternator slightly. with a gear or  pulley
it's been done before.
you can even  build another complete windmill section and stack them up to give you more torque against the load .
if you search the archives over at the vast site some one build a counter rotating stator.
if this is your first build  i would bite the bullet and turn another set of coils and stater. you will then have a properly functioning lenz 2 windmill
.
you can now experiment with your heavy  wire stator to see what sort of rpm it likes


"Because your PMA is air core you should be using a lift style blade."
 
that's whack advice odin !

[velacreations]

I bought the magnet wire back int he days when it was cheap, so it's what I had.

I am looking at my options, but buying more copper and making a new stator is out of the question.

I would rather drop in larger magnets and/or change the blade design.

[electrondady1]

so you will trash the wings you built,? and construct new ones ? or buy new mags in order to use the same stator ?
wow. that's kind of the inverse of how mills are usually built
let the guessing games begin.
the coils geometry requires you use pretty much the same size mags and rotor . with caution you can stack another set of mags on the existing mag rotors.
 doubling their thickness. it won't be a 100% increase but it will certainly increase flux density.
 

[velacreations]

well, I already have the other magnets, so I just need to make the discs, not that difficult, and the magnet discs I am using could go to a future HAWT or something.

Yeah, I am willing to change blades to make it work, mainly because more copper wire is a significant cost and I live in the middle of a 3rd world country where resources like copper wire are not readily available.

I am still looking at my options, and just asking for advice.  I haven't decided anything, but doing another stator right now is low on my list of viable options.

Thanks for your help, though.

[electrondady1]

when i got started i built a machine to turn coils.
 and can lay down two turns a second.
i love turning coils so i guess every one has different priority's
good luck on your project.

[electrondady1]

are the other set of mags the same as ed"s ?
do the have the same dimensions ?

[velacreations]

are the other set of mags the same as ed"s ?
do the have the same dimensions ?

no, they are the Fiedlines 2" x 1" x 1/2", so considerably thicker than Ed's.

[jlt]

    I would  try to use it for charging a 6 volt battery.
There are A lot of uses  like LED lighting.  Or cell phone chargers to name A few uses
                          JLT

[dave ames]

#3. Seems we are still just outside the airgap limit for those thin (compared to the gap) magnets...I would try stacking a layer of the big 2x1x1/2 neos on outer disk if there is still enough adjustment available and give it another spin. <- I'll wager that you may have to start adjusting the airgap back out. 

Great fun! Thanks for the look 
Cheers, dave

[velacreations]

#3. Seems we are still just outside the airgap limit for those thin (compared to the gap) magnets...I would try stacking a layer of the big 2x1x1/2 neos on outer disk if there is still enough adjustment available and give it another spin. <- I'll wager that you may have to start adjusting the airgap back out. 

Great fun! Thanks for the look 
Cheers, dave

hmm, that is interesting, adding the other magnets on the outside for testing.  Should I do that with both discs?  I guess that would give us an approximation of how well changing the magnet discs will help.

Thanks for the suggestion!

[dave ames]

oops...Outer disk= the easy one to get off and on.

Stacking = right on top of the wedge ones..

Easy enough to do one and see what happens, we may not even have to glue them down at these low speeds for testing

[velacreations]

oops...Outer disk= the easy one to get off and on.

Stacking = right on top of the wedge ones..

Easy enough to do one and see what happens, we may not even have to glue them down at these low speeds for testing

ohhhhhh!  thanks for clearing that up.

I have more wedge magnets, I could put a layer of them on, and that would get close to the thickness of the 1/2" magnets.

[Flux]

Stacking more wedge magnets on the outer disc will most likely do the trick, As+9 Dave said if you stack the rectangular ones on the wedge ones you will probably be slower than you need.

I also think you can do the test in low wind with then just held on by the magnetic attraction but a good layer of gaffer tape may help.

Flux