New Wind Turbine Flying

[egreen]

My 5.5' wind turbine has been up and running now for a few weeks.  I posted photos in my last post from a few weeks ago.

Specs:

16 magnets, dual 8 inch rotors, 12 coils (16 ga wire), 1/2 x 1/2 x 2 inch neo magnets, 1 inch air gap, 5.5' wood blades, 12 volt cut-in @ 220 rpm.

Questions:

1. The most power that I've seen out of it so far is ~128 watts (16v @ 8 amps).  Is this good for a turbine this size?  Would it be resonable to add larger blades to make more power or is the stator not capable of handling any more power?  The turbine is fully furling in what I would estimate to be 15 mph winds (I plan on getting a hand held anemometer soon) with a 12 volt battery load, although I know that it has been in gusts over 20 mph.  Should I add weight to the tail to make it furl later so that I could get a bit more power?  How fast should a 5.5' turbine spin before furling?  The blades already make a humming noise in high winds and spin so fast that they look like a blur.  I want to stay safe so that I don't burn out the stator.
   
2. The wire from the turbine to the house is 14 ga romex @ 50 ft run before it is rectified to DC.  Is 14 ga enough or should I go bigger?  12 ga or 10 ga maybe?
   
3. How many amp-hours should the 12 volt batteries be for this turbine?  Does the battery storage capacity depend on the power of the turbine or what I'm going to be running with my 300 watt inverter?  Is there a general rule of thumb for this?
   
4. I just recently purchased a tristar 45 to be a diversion load controller and a 300 watt 1/2 ohm air heater resistor for a dump load.  I'd like to get one of the IOTA 30 amp automatic transfer switches and have it switch between the inverter battery power and the grid power to feed 1 circuit in my house.  I'm planning on adding a 45 watt HF solar panel kit this summer.  Am I going overboard trying to feed a circuit in my house when the total battery charging capacity will be less than 200 watts?  I'm not trying to save a bundle on electric bills with this setup but I'm tired of carrying batteries and the inverter from the garage to the house.
   
   

His files are over HERE Some are too big to include but worth a look. TW

[wpowokal]

Looks a neat project, just one comment, are all nuts done with locktite? or locking nuts because do not underestimate the vibrations present on a wind turbine.

allan down under

[Janne]

Nice looking work! It looks like the hub will be well secure with that many bolts holding it on. There is a slight drawback with that arrangement however, the wood will tend to crush if you pre-tension the nuts enought to prevent them loosening on their own.. So like Allan suggested, it might be a good idea to secure the nuts with loctite, or some else method.

I learned this with my axial mill, I used 6 8mm bolts to hold each blade, and they just wouldn't stay tight, the wood crushed under the pressure.

Is the yaw bearing also a pillow block one?

[tecker]

 Looks like the total gap you mention includes the stator. That's a little thick . Try to lessen the gap if you can to increase the output . Change the wire to #8 SO cord down the pole Set a water proof box and tap the down wire there . Run the home run to your Battery box to cover 40 amps (Two # 10 per phase) . I like the pillow Blocks with Grease fittings nice job very well thought out . A good Idea overall to move the mech away from the mast . Keep posting the results . If your climbing to 16 volts into your batteries you have more amperage availible to larger batteries Sounds like you are using car batts or SLA or some thing like that . Good deep dischrge batteries will take all the amperage the 14 wire will carry so when you up the batteries you need to have larger wire to see the max from the Genset. Good build and keep posting.

[TheCasualTraveler]

    I like your nuts and bolts approach although I see some welds too. Can you tell more about the shaft and pillow blocks? The bearings seem to have set screws and the shaft looks smooth. Is the other end of the shaft threaded? How are the magnet rotors held on the shaft? What size is the shaft? Did you consider mounting the blades on one side of the bearings and the alternator on the other? Saw blade behind the blade set, nice.

[Ekij]

A 5.5' (1.6m) turbine with "typical" efficiency should produce

58. W at 12.6mph (modal wind speed)
    
98. W at 15mph (Average wind speed)
    
232. W at 20mph
     
8. A is reasonable for 16ga, you could probably squeeze a little more out of it.
   
   

> Should I add weight to the tail to make it furl later so that I could get a bit more power?

That's the question. Do you think the mechanics can take more force without damage?

> The wire from the turbine to the house is 14 ga should I go bigger.

Sounds like 14 ga is sufficient.

> How many amp-hours should the 12 volt batteries be for this turbine?

Wrong way up. The question should be "how much battery do I need to power my load for a 'reasonable time' when there is no wind". You match the batteries to the load, not the turbine.

[egreen]

I have lock washers under every nut.  Do you think that I still need to use locktite?  I had to use locktite on my ametek turbine because the pvc blades created alot of vibrations.

[egreen]

Next time I lower the turbine I think I will locktite every nut and bolt even though there are lock washers.  For the first couple of weeks that it was flying I wanted to hold off on the locktite until I knew that everything was going to hold together and so that I could make adjustments if necessary.

I know what you're talking about with regards to crushing the the wood on the hub because even though I have large diameter washers it still made slight indentations in the wood when I torqued everything down.

The yaw bearing is a 2 inch pillow block bearing.  To keep the bearing from moving in the housing I had to lay a weld bead between the outer bearing and the housing.  This is the only weld on the entire project that I did which was questionable because the bearing housing is cast iron and the bearing is steel.  I didn't use nickel filler which is what I think is recommended but I did preheat the housing with a tourch.  Anyway, the turbine turns effortlessly into the wind.

[egreen]

The gap does include the width of the stator, I thought that's the way the air gap is measured.  Sorry if I was mistaken.  There is only a 1/8 inch gap between the rotors and the stator so unfortunately I can't get much closer and shrink the gap.  I figured that since the total magnet width was 1 inch that a 1 inch gap would be okay.

Thanks for the kind words regarding the pillow blocks.  However, it seems that the pillow blocks have gotten mixed reviews.  In my previous post, Flux was questioning if they would be able to handle the load.  I'm crossing my fingers though, so far so good.  It has already been in 20+ mph winds and it appears to be okay.

I've tried charging both 12v car batteries and 3 - powersonic 4 volt 10ah AGM SLA batteries hooked in series.  I noticed that the car battery takes higher amperage than the small AGM batteries.  The car batteries took 8 amps but the highest amperage that I saw going into the AGM batteries was only around 5 amps. Perhaps they are too small to take the current.  My plan is to buy much larger AGM battery, like maybe 100ah.  I'm hoping that they will take higher charging currents.

[egreen]

When I started the project I didn't have a welder (never welded anything before) and I was going to try and bolt everything together.  But in the end I purchased a HF TIG welder and it made the construction of the frame alot easier (I must say that the small HF 130 watt inverter TIG welder is really nice and does a great job).  It's nice though that I can take the whole alternator assembly off with 4 bolts (and the stator bolts) and leave the frame hooked to the yaw bearing.

Actually I didn't use any saw blades.  All of the discs (except the front blade hub) are just 8 inch gears.  The shaft is 3/4 inch solid steel with a key notch running the length (no threads).  Each gear hub is held on with 1 key and 2 set screws (which I put locktite on).  I'm not sure if you can see in the picture but there are also 2 threaded rods running between the 2 rotors (drilled and tapped) to keep them from every moving any closer to one another and crashing the stator.  The pillow block bearings have eccentric locking collars with set screws (with locktite).  The bearings, gear hubs and the shaft I got at surpluscenter.com.  Around 100 bucks for everything including the yaw bearing.

I didn't consider mounting the blades on one side and the alternator on the other, although that might be a good idea for the sake of the bearings.  It would probably balance the things out a bit instead of having all of the weight on one side.  However you'd have to make sure that when the tail furls and swings around that it doesn't hit the alternator assembly.

[Warrior]

Hi, nice work! I'm no expert but I'd say you are getting good power from it. The problem is that we rate turbines based on power but whats really important is energy capture.

Us humans are greedy by nature and we always want more. I'd say leave it as is for a while and see if the energy production meets your needs. It might fry if you add too much weight the tail. Don't underestimate the power wind has. It can really destroy a well built unit.

Good Luck!

[egreen]

What's the fastest that a 5.5' turbine should spin?  I can probably measure it by putting a reflector on the rotor hub and use an optical tachometer that I could temporarily mount to the turbine (this is the technique I used to find the cut-in @ 220 rpm).  I think the turbine is furling before the wind reaches 20 mph (just speculation because I don't have an anemometer).

If I should let the turbine spin faster for its blade diameter then I would try putting more weight on the tail.  The only thing that I can see that may go wrong is that the bearings could go bad.  Which isn't a big deal because I ordered replacement bearings and they only cost 6 bucks each (without the pillow block housing).

Thanks for the answer regarding the batteries!  I wasn't sure what determined the battery capacity.  Since the turbine puts out ~120 watts I figured that it should be okay to run a house circuit that uses ~120 watts (120 vac @ 1 amp / 12 vdc @ 10 amps) occassionally.  Do you think that a 100ah battery is enough?  Theoretically I guess that would mean that I could run a 120 vac device @ 1 amp for 10 hours (minus loss of the inverter).  Plus since I would be using the battery on a 10ah draw (not 20 ah) so the 10 hours would probably be more like 8 hours.  The inverter will only put out 300 watts anyway so that's only about 2 1/2 amps @ 120 vac or 25 amps @ 12 vdc.  I figured that I could run my laptop, small tv or some lights for a short period of time.  It would take quite a bit of time I think for my turbine to charge a 100ah battery.

[egreen]

I want to thank whoever it was that added the link to my pictures to this post.  I'm assuming that TW is one of the forum admins, Thanks TW!  Sorry for posting pictures that are too big.  I thought that I cut them all down to 640x480 or less.  I can try to shrink them a bit more.  Also, how come 2 of my images have a '.' and a '..' instead of the actual image names?

[egreen]

I understand the concept of always wanting more power (like Tim the tool man)... haha.

I was asking about the power output because when I first started this project Flux had mentioned to me that I may be able to get close to 300 watts from this turbine if I build it right.  Well, I think I built it right (at least to the best of my ability), however I'm not sure if there is something that I'm doing that is causing it to not perform to its full potential (ie. furling too early, wire from the alternator is too thin, using the wrong batteries, etc).  Don't get me wrong, I'm very pleased with the results of this project.  If this is all I can get then I'm happy.  But I figured that it can't hurt to ask

[TomW]

egreen;

"TW" be me! That . and .. thing is a Scoop bug we have to live with for now. There may be more files under the "." but the ".." moves out of your file area. Try clicking the "." it might show more files.

Hard to explain but its a new problem thats crept in thats slowly getting worse.

Just FYI.

Tom

[hiker]

nice little alt..

somthing like my 9&12 alt--jerry rigged..

  just my opinon--but i think you would have had better output

with a 9&12 setup-- would have been able to use bigger mags and coils.....

 

[dlenox]

egreen,

on my wind turbine I use flat washers backed by lock washers, locktite and as extra precaution double nutted each one.

may be overkill but lots of vibrations up there...

Dan Lenox

[Ungrounded Lightning Rod]

Yes, for a coreless machine (like the typical axial flux designs here) the "air gap" includes the stator.  You should probably refer to "clearance" when you're talking mechanicals.

Unfortunately a lot of people also say "gap" when they mean "clearance".  I presume tecker was just confirming which definition you were using rather than trying to suggest a confusing (and non-preferred for this board) usage.

[Ungrounded Lightning Rod]

Furling isn't (mainly) about keeping the mill from flying apart in high winds (or striking the mast on a sudden yaw due to gyro forces).  It's about keeping the genny from burning out.  That is normally a far lower RPM limit than anything related to the safety of the blades.

So max sustained blade RPM will be about TSR times wind speed (if unfurled) at the max allowable power point (though it probably actually occur at a somewhat higher wind speed with the mill partially furled).

You can figure it out easier from the electrical characteristics of the genny and charging system.