Fieldlines.com: The Otherpower discussion board

Xeon has a little lamb, little lamb...
Adorable.

If the batteries are charged, and no loads taking power, it would be normal to have 110v on the solar pv input side.  It just means the charge controller isn't letting current flow through, so the pv modules output their open circuit voltage (voc) 

Your low voltage disconnect suggests that the batteries aren't full.  Maybe your charge controller is staying in Float, and the rebulk voltage is too high?
Are you using custom voltages or preprogrammed ones? Does the tristar have a setting for lithium? I have one in the basement running, but I don't remember anything about lithium settings. I have lead. 

Also, what is your low voltage disconnect set at?

This guy went with an exterior scoop, and its a pretty similar radius IMO.

https://www.youtube.com/watch?v=h-FqF21wyLc

Notice his pulley size.

Hi Lars, and welcome.

You have a really sleek looking turbine; some nicely printed pieces for sure.  I hope to see more as things develop.  You've probably already figured out that you'll get a wide range of perspectives here on any given topic, and the trick is to wade through them.  In the end though, I believe it helps the design process.  The comments have been good.  I don't have a lot to offer, but for what it is worth...

I think your blade connection at the hub may be something you have to beef up.  I'd be concerned that the reduced width might be a weak point without added thickness or some sort of strut.

A couple of us here have been using MPPT type controllers (Midnite Solar, Classic).  They are not a true "feedback and adjust" as with solar, but rather they allow you to input a power curve that follows the curve of the alternator.  One benefit though, is that the curve can be tweaked, if it is not perfect from the start.

I do agree that it is best to attempt to keep things electrically loaded to the extent possible - I think that was Sparweb's intended message.  Side-furling works well.  It's time proven.  If a turbine runs unloaded, in a good wind site for any amount of time though I would say it is only a matter of time before something fails.  It will spin up to rpms that it is not equipped to handle, furl, slow and repeat.  To touch here on that "wide range of perspectives" I mentioned earlier, here's a prime example where we get deep in the theoretical discussion on the one hand, but then make broad-brushed summations based on very limited, antidotal experiences on the other.

Good luck, and I hope to see more, ~ks

you'll learn you never have enough batteries lol!

for years I lived off of 10.3kwH of lead acid (5.5kwH usable) just too small

Now got 18.4KwH of lithium (12.9KwH usable that's to 80% depth of discharge, safe for lithium's) got to add 2 more sets yet!

But I can tell you, do what ever you need to get to 48v as that will be the largest pay off long run for ya!

The Hybrid inverters deff pay off too, some people have done nifty things with the settings to make them really perform as a solar first utility second device.

Baaaaa!

 go on ebay and find this book.  Getting started in electronics  by Forrest Mims

MAKE SURE YOU GET THE GREEN BOOK

Hello Lars,
Have you set up with wind turbine outdoors in the wind yet?

NEVER RUN A WIND TURBINE UNLOADED.

If it isn't allowed to run a certain wind turbine unloaded, there is something seriously wrong with the safety system. The safety system which limits the rotational speed and the thrust must be that good that even an unloaded rotor won't be destroyed at high wind speeds. Reduction of the rotational speed only by the load is dangerous because the required electronics to steer the load may fail and this results in an unloaded rotor.

I have tested the hinged side vane safety system of my VIRYA-4.2 wind turbine with an unloaded rotor and although an unloaded rotor is rather noisy, the rotor running at the maximum rotational speed gave no problems at very high wind speeds. The VIRYA-4.2 has a 2-bladed rotor with a diameter of 4.2 m with constant chord blades made out of massive mahogany wood. The design tip speed ratio is 8 and the unloaded tip speed ratio is about 12.8. The blade chord was 200 mm and the Gö 623 airfoil was used. The maximum unloaded rotational speed was about 480 rpm, so 8 rev/s. The maximum loaded rotational speed was about 300 rpm so 5 rev/s. The slender blades of this wind turbine are sensible for flutter at very high tip speeds but flutter didn't occur for an unloaded rotor.

Are you making a backup JW?

hahhah this newbie did find eventually a guide on how to use gravity as a torque/breaking force measuring device.

sweet.

I am going down that path!! to see if I can get anywhere with my original plan.

@SparWeb,
I found your 2006 document at
http://www.jimic.cl/appv/Congreso/PDF/AXIAL_FLUX_HowItWorks.pdf

It describes the Dan Bartmann Axial PMA Ed is refering to, for which I have all 16 magnets in at the moment.

But in the end you write the following
"At 80 RPM, this alternator will produce 50 Volts, unloaded. When connected to a 48V Battery
system, Dan has recorded 600 Watts at 100 RPM. (Roughly 12 Amps). This is actually a
fairly large PMA, suitable for a windmill size of about 17 feet diameter. At higher wind speeds,
the prop turns much faster and he can capture upwards of 3 kiloWatts."

This is in stark contrast to what I am aiming for. Roughly 52V open circuit at 4 RPM.

@MagnetJuice
What I meant with breaking force ability was inspired by Joestru when he mentioned mechanical resistance and MaryB when she mentioned cogging and how much force it takes to overcome it.
The current charge controller I have will short all 3 phases to slow down the turbine. But if the coil/magnet configuration can't produce enough torque/breaking force then not much breaking will happen.
On the same token, if there turbine is charging the battery bank but not much resistance in the turning is being produced then there will be very little wattage available to charge at.

If I say it's intended, clearly it's not a "problem".

Hello Lars,
Have you set up with wind turbine outdoors in the wind yet?

The explanations you've received so far are excellent, so the only improvement possible is for you to take that thing outside on a windy day and observe it, and take measurements of what happens.  You should run it without the MPPT controller at first. 

Set it up on a rigid post, pole, or structure.  Being a temporary set up for test I won't direct you too much but just make sure it won't flip over with a 100 Newton push against the blades.  Be mindful of your own safety doing this, however, and if you stop reading now, ignore the warnings below, and carry it outside and hurt yourself - it's your fault, not the anonymous stranger on the internet. 

First make sure you have shorted the output wires together and expose it to a strong wind in that condition.  If there is a terrible mis-match between the rotor and the motor you will find out quickly enough.  Shorting the wires permits the maximum current to flow, which usually means too much torque for the blades to turn.  This is a brake.  You want a brake, for safety.  If this brake works, it will help ensure your WT is safe in the future, too.  It should turn very slowly in this condition even in a strong wind.  Any other behaviour is not acceptable.

If it does spin uncomfortably fast with leads shorted, don't try to grab the blades!  Regain control by turning the tail by hand until the rotor is facing  sideways to the wind.  Then bring it back indoors or in the lee of a building to sort out why shorting the leads did not restrict the blades.  If shorted leads can't make the blades turn slowly, then stop now, redesign this WT, or start fresh. 

When you are certain it will not spin out of control with the wires shorted, then you can allow it to turn with resistance or battery charging loads.  I would do this to characterize the behaviour of the WT before installing the MPPT.  You will not be able to demonstrate the effectiveness of your MPPT device if you don't know what the characteristics of the WT were before you installed it!

NEVER RUN A WIND TURBINE UNLOADED.

Isn't the RPM area for a given turbine only determined by the rotor size? I understand that a wind turbine harvests the most energy from the wind if it operates at the optimum tip speed ratio (typically around 7 for a three-blade HAWT). If the wind speed is 10 m/s, the tip speed should ideally be 70 m/s, which corresponds to a specific RPM for a given rotor size. A small turbine would have to spin faster to operate at TSR=7. This logic is further elaborated in my original post. I think this is the core of my problem, so please tell me if I'm missing something here.

Thank you for the generator suggestion MagnetJuice. I have also been looking at this one:
ebay.co.uk/itm/235042332008?chn=ps&_ul=GB&var=534977374051&norover=1&mkevt=1&mkrid=710-169684-097358-0&mkcid=2&itemid=534977374051_235042332008&targetid=293946777986&device=c&mktype=pla&googleloc=1010976&poi=&campaignid=20649918451&mkgroupid=151788312862&rlsatarget=pla-293946777986&abcId=&merchantid=6995734&gclid=Cj0KCQiAw6yuBhDrARIsACf94RV3voAhQUyhNRR0LcWsCQCp3uWbPtWYMEVdzHyCNEoHbJthoCFvIxwaAqJVEALw_wcB

I have also another question. Some of you are talking about the cut-in speed where the generator will output 12V. Is there a problem with just using a buck-boost converter?

Greetings,
Lars Erik

Watts generated is determined by rotor size... that is where you need to start. Just because it says it will do 200 watts doesn't mean it will do it with a 3 foot rotor. Research power available vs rotor size.

You start with determining how much power you need, then start looking for an appropriate alternator that reaches that at the lowest possible RPM because high speed on a wind turbine is SCARY. Rotor blades can explode from the forces... tossing shrapnel for hundreds of feet. That is why the axial flux alternator is so popular on this site, it can be designed with low cut in speeds... I for one would not want a set of blades up there spinning at 750RPM at cut in speed!!!!!

Isn't the RPM area for a given turbine only determined by the rotor size? I understand that a wind turbine harvests the most energy from the wind if it operates at the optimum tip speed ratio (typically around 7 for a three-blade HAWT). If the wind speed is 10 m/s, the tip speed should ideally be 70 m/s, which corresponds to a specific RPM for a given rotor size. A small turbine would have to spin faster to operate at TSR=7. This logic is further elaborated in my original post. I think this is the core of my problem, so please tell me if I'm missing something here.

Thank you for the generator suggestion MagnetJuice. I have also been looking at this one:
ebay.co.uk/itm/235042332008?chn=ps&_ul=GB&var=534977374051&norover=1&mkevt=1&mkrid=710-169684-097358-0&mkcid=2&itemid=534977374051_235042332008&targetid=293946777986&device=c&mktype=pla&googleloc=1010976&poi=&campaignid=20649918451&mkgroupid=151788312862&rlsatarget=pla-293946777986&abcId=&merchantid=6995734&gclid=Cj0KCQiAw6yuBhDrARIsACf94RV3voAhQUyhNRR0LcWsCQCp3uWbPtWYMEVdzHyCNEoHbJthoCFvIxwaAqJVEALw_wcB

I have also another question. Some of you are talking about the cut-in speed where the generator will output 12V. Is there a problem with just using a buck-boost converter?

Greetings,
Lars Erik

The most important neighbor in my case is the wife.

The nastiest noise I've ever had was when the top of a tube was being rubbed.  Kind of like the sound a glass makes when you wet your finger and do circles across the top.  Only about 1,000x louder.

When I try to upload a pic im getting "fakepath" in the link to upload

I second MagnetJuice's comments.   Radius of 0.6m = ~4 foot diameter.  Your 121 RPM/volt spec on the data sheet is about 5x too high to hit a useful voltage.  There are better BLDC motors out there with lower KV ratings, though getting down in the 15-30 kv range will be challenging without coging too much for start up and not being too expensive.

For example, 20 RPM/volt * 12 volts = 240 RPM cut in speed.

I should NOT have said forget about Teslas and breaking force.

I should have said:

For now, concentrate on number of turns, resistance, air gap, RPM, volts and amps.

Other things like Teslas, braking force, cogging and terms like that are important, but they will become clearer to you once you have your testing setup and start doing the testing.

quote from brandnewbell:

I just have not enough evidence to just give up on the breaking force concept that @joestue started yet never followed up on."

Now listen, this is very important.

When it comes to the definitions that different people give to technical terms, there could be differences and sometimes misunderstandings.

I want you to define to the best of your ability, what do you mean by breaking force. Please do that for me so I have a better understanding of what you mean.

Ed

Small axial generator to build a working model of a windmill.

 

With air core coils cogging isn't an issue to worry about!

What is the difference of shorting the phases to shut a mill down.

The way your top and bottom allow leakage out of the blade is a must.  Its okay to have holes in your blades, preferably to only induce enough drag to get the result you want.  Human nature leads us to create cups, but if the air cannot leak then stagnant air gathers at the blade.  The leakage allows stagnated air to clear the blade.  The barrel-conversion savonius designs often prevent this leakage and it kills efficiency.  The air should flow around the blade rather than be stopped/blocked by it.  You want that clean air to be accessible to the blade.

Yes brother, please keep it coming!!.

Yet before I had a chance to even start on poking holes in the blades the Pheonix had other plans.

She started to generate a sound that resembles a middle C of a piano. Something around 256Hz. {1}or 440 Hz wha Ii actually believe to be more accurate{/1}

Needless to say now my focus is on what it is she is trying to tell me.

I already have a strong indication that it is this bearing I use to keep the bird upright.

Now if ever I have had a good reason to go scify then now is it.
I mean if store bought bearings start failing  then why not try something more futuristic?

I know of 11 forms of intelligence Bruce. So I think you are still the smartest Bruce I know of. In most of those categories

But let us not linger on reproduction extremities measuring contests