A new commer Trying..

[Instinctz]

Hey, well I am very new to all this alternative power.. but im experimenting.

I have just built a very simple and most likily uneffiecient 3 bladed prop for my up-comming generator.  I am just curios about after rectifing the power to DC if needed how do I begin to charge my battery bank?  Once the windmill is set up I will probably get about 4 deep cycle batt's from wall-mart or something in a 12v setup.  I will just bet lighting a set of lightbulbs (5-10) for this first experiment.  To see how often I will have to watch out for power drop outs.

I then plan on upgrading the windmill blades, increasing the height of tower, and all other low points of the system once I get a better understanding of how these systems work in a whole.

[Titantornado]

Welcome to the board Instinctz.

Alright, well, there are really crude ways of doing it, (which are the most affordable) and advance methods via electronics. (which will cost you more, unless you are good with those kinds of things)

Let's look at the crude ways, since you're just getting into this.  From the recifier(s) you can connect directly to the battery.  There, done!   OK, not quite that easy.  You will, of course, have to play the part of the regulator.  This can either be done by disconnecting the generator once the batteries have charged. (and short the generator leads on the AC side of the rectifier(s) to stop it, and prevent it from freewheeling out of control)   Or, you can simply turn on and off various loads connected to the battery bank to regulate the voltage of the batteries.  (the windier it gets, the more loads you'd have to turn on)  Obviously, this would be demanding of you to constantly monitor the battery's charge, but it will work.

Of course then, there's charge controllers that do the work for you.  They determine how much power the batteries get and divert any extra into some sort of auxillery load.  It all comes down to how much you'd want to spend, but smaller systems are typically fairly affordable.  It's only when wind generators start going above 35 amps that prices start to climb.

The decision is yours.

[Ungrounded Lightning Rod]

You will, of course, have to play the part of the regulator.  This can either be done by disconnecting the generator once the batteries have charged. (and short the generator leads on the AC side of the rectifier(s) to stop it, and prevent it from freewheeling out of control)

Just short it upstream of the rectifiers - you don't need to disconnect them.

Watch out for frying the genny in a high wind, though, if your furling isn't working right.  (Dump loading is better anyhow...)

Or, you can simply turn on and off various loads connected to the battery bank to regulate the voltage of the batteries.  (the windier it gets, the more loads you'd have to turn on)

You don't have to do this minute-by-minute, of course.  Just check the state of charge every day or so and decide whether to run your big loads that day.

Don't worry about overcharging too much:  Just check the water often and make sure the batteries don't run short.  (Overcharging electrolyzes the water into gas that flies away but mostly doesn't bother the batteries otherwise until so much goes that the plates are uncovered.  Then things go downhill fast.  Without an auto-switched dump load you'll need to check the batteries weekly rather than monthly or quarterly and buy a lot of distilled water.)

And try to keep 'em near full charge, and at it at least once/week, to prevent sulfation.

But you'll want to automate this within a couple months after you get things working.  Charge/discharge cycling wears out the batteries, and having your state of charge automatically controlled minimizes that cycling.

[Instinctz]

Thanks for the comments guys, well I am slightly novice with understanding electrical circuits so if I understand things right I may have a design that will work.

lets say I make a 3 phase alt creating near 14 volts.. once the windspeed picks up enough to create a voltage higher than the battery bank it would throw the relays to begin charging.. untill the battery bank reaches full charge.  Then I could throw relays which would short out the phases and end charging cycle.

Currently I havn't quite figured out all the variables to making an alternator but Im tring to read up more about how the coils, magnets and other parts go into creating the current.  I dont believe for now I will be going much over 15 amps at any one time.  So my electric circuts should be inexpensive.

I will eventually be making "yet another" Alternative Energy website cause I havent really found one that has given me the information I was exactly looking for.. in well my format of learning hehe.  But mainly just documenting my own experiments for me to remember about.

Thanks,

[Ungrounded Lightning Rod]

lets say I make a 3 phase alt creating near 14 volts.. once the windspeed picks up enough to create a voltage higher than the battery bank it would throw the relays to begin charging.. untill the battery bank reaches full charge.  Then I could throw relays which would short out the phases and end charging cycle.

Nope.

You leave it connected all the time.

At low winds the battery doesn't discharge through the genny because the diodes in the bridge rectifier block back currnet.

As the wind picks up the voltage on the genny output rises.  Eventually it begins to exceed the battery voltage plus the diode drop.  Then current starts to flow into the batteries.  (This is "cutin speed".)  No relays required.  As the wind speeds up further the current is limited by the resistance of the generator coils and wiring, so it rises but doesn't go sky-high.

Meanwhile, the current produces a force that fights the turning of the shaft.  Until the current started flowing the shaft speeded up in proportion to the wind speed.  But now that it's charging its speed rise is at a much lower proportion.  (If the genny and its wiring - including the battery internals - were built out of superconductors, it would reach cutin speed and go no faster, with the additional wind speed producing higher torque - and higher current - but no faster spin.)

This speed-restriction by battery loading is important to keep the mill from running away to extreme speeds in high winds or gusts.  That can result in the mill coming apart and throwing pieces around at a couple hundred MPH (grenading).  So it's important not to disconnect the mill from the battery (or some other suitable load), ever.  (Exception:  If your rectifier falis shorted you could put massive currents through the genny and start a fire.  So you use a fusable link - a high-current fuse - to prevent that, and take your chances with the mill grenading before the furling mechanism turns it, rather than a guaranteed fire.  Fortunately, shorted diodes also load the mill, so when they fail shorted you're normally OK.)

But with the mill always connected to the battery it can fill it and keep going - like a river flowing into a full reservoir and overflowing the dam.  Solution:  Add loads to "dump the extra water".

Stopping the mill (i.e. by shorting it) is also good.  But you don't want to do that automatically - because the wind may be high enough and your genny weak enough (and your furling set too high) so that it DOESN'T stop.  Then all that power is dumped as heat in the genny and it burns up.  So dump loads are best, and shorting the genny is a second-choice that should only be done manually (so you can notice that it didn't work before it fries, and turn the short off again - then turn on all your lights and stuff, or lasso the tail and pull the mill into furled position, or just let the water electrolyze away in your batteries and make a note to top them off in the next few days, before the plates get uncovered.)

[Instinctz]

Wow thanks, that enlightened a large majority of my dark area's in understanding those little 'need to know' things.  So basicly once I build the alt. to obtain x voltage with y phases it will only create the x voltage at every rpm? Perhaps with a slight variances?  Then the only other factor changing with RPM will be amperage due to the magnetic resistance?

[Ungrounded Lightning Rod]

Above cutin, effectively, yes.  The battery will "clamp" the voltage (very "hard") to the battery's reaction voltage, which is nearly constant.

What's happining is the voltage INDUCED in the coils continues to go up with RPM.  But the voltage at BATTERY'S CHEMICAL REACTION is constant, varying only with the temperature and state of charge.

There is resistance in the circuit, and that causes a voltage drop proportional to the current.  (Also, there are some non-linear resistances in the circuit - like the diodes and the resistance from gas bubbles on the plates.  But they're pretty minor.)

So the voltage measured at the BATTERY TERMINALS is NEARLY constant, rising slightly with RPM.  The voltage at the GENERATOR TERMINALS shows a significant rise, since it is above the battery reaction voltage by the additional voltage drop in the genny-to-battery wiring and the rectifiers.  But it's still below the INDUCED VOLTAGE by the voltage drop from the current in the winding wire's resistance.

Meanwhile the higher the current, the harder the genny fights being turned.  So the RPM and thus the INDUCED VOLTAGE doesn't rise as much with increases in wind speed as it did below cutin.

All this current flowing through voltage drops represents energy lost as heat.  You have to keep that from getting too high for too long, accumulating faster than the air can carry it away, or the heat will damage the genny.  Reducing it by cutting the load lets the genny speed up, possibly "running away" to speeds that can damage the turbine.  So some other way of "furling" the mill may be required.

(I did a big writeup on furling at this point but then realized you've probably already read about it.  So I deleted it - but saved a copy if you want to see it.)

[Instinctz]

I have read quite a bit about the furling, I realize that its an act of gravity that helps 'push' the blades out of direct wind to reduce the increase in speed somewhat.  Now the actual geometry of the furling system and what not I dont have memorized as of now but I've have a few resources to look at.

I orginaly was going to just throw a setup together to see how things go.. but I believe im going to skip this initial design for something atleast somewhat usable.  Like the blades I have now are basicly MDF (a quite heavy material) built to a slant and wedged between two other peices.  It does turn but doesnt seem to be much of any efficient means.  I also was just going to try and use a motor to design the induction genorator but have just about scraped that idea as to see'ing how much more efficient home built stator genny's are.  

I really appriciate all your help, it appear's you have much of the physic's and math memorized to help out with.. which is how I learn by.  I believe i'm going to try and get ahold of some wedge magnets and wire to begin assembling a genn from scratch.  I all ready have opt. for a duel magnet rotor design.. just trying to figure out how many coils and blade length I should go for now.

..

I havn't found any real good resources for informing me of how the stator works exactly.. so if you have any helpfull phyics on the wire length,size,turns about how the power is created would be really enlightfull.  Of course if you have a favorite page that has the info, a simple link would suffice.

Again, thanks.