some questions for the wind gods

[tripper]

hey crew

-long time listner first time caller

1. to recharge a battery its best the voltage is about 13.8 right? well what happens if the wind picks up and the voltage increases? does a 12v battery still charge if your are pouring in 20v? what happens to the battery?
   
2. southwestern wind turbines claim that their "Air x" is the only turbine that takes advantage of the power of the wind cubed every time the speed doubles....how could a VAWT also acomplish this?
   
3. what does a battery regulator really do (besides regulate) by that I mean how does it regulate? does a regulator simply vary the voltage? and does a regulator contain a buck/boast converter....or is a different matter altogether.
   
   

ummm....thats it I think

Cheers for any feedback

trip

[finnsawyer]

1.  The battery voltage will not rise to twenty volts.  Instead the wind driven alternator current will rise until the power driven by the windmill will match that going into the battery plus that lost or dissipated in the alternator and the battery itself.  (The battery does have some internal resistance.)
   
2.  Getting a good match between the wind energy curve and the alternator performance curve is not easy.  Sometimes two points on the curves matching is considered acceptable.  Beyond that one can design the alternator with tapped windings or as in the case with the auto alternator with a rotor winding.  Since I don't know what Air x does I'll pass this on.
   
3.  Basically, the regulator keeps the battery charging current within prescribed limits by sensing the voltage across the battery.  For instance, with the 20 volts applied and a battery voltage of 13.8 volts there is a difference of 6.2 volts.  This voltage has to appear somewhere, so it appears across the regulator.  If there is 20 amps of current going into the battery the regulator then must dissipate 134 watts of power.  In the case of an auto alternator the input voltage is also controlled by reducing the rotor current.  You don't generally have that option for a wind power system.  The voltage will increase with wind speed.  So the regulator must be able to handle this power (or cut back the current, which you probably don't want).  At some point you need to either dump excess power or furl the windmill.
   

[farmerfrank]

1. Maximum voltage for the common auto battery is 13.2 or 2.2 volts per cell. After it reaches this voltage the acid solution gets warm and begins to lose water fairly fast through evaporation.
   
2. Pass
   
3. A regular regulates voltage while a charge controller limits amperage.
   

[tripper]

Cheers GeoM

What are tapped windings?

How can you furl a VAWT....?

[RP]

Tapped windings are what you get when you provide connection points during the coil winding process at less than the full number of turns.

For instance:  On a particular generator with 100 turn coils that produces 100 volts at some rpm, if there is a "tap" or connection on the 75th turn, then a connection to this point will produce 75 volts.

In reality with a battery load, its the current that will go down since as was explained above, the battery will try to hold the genny down to the battery voltage.

[ghurd]

#1  You could be confusing watts with volts.  Read up on 'ohms law'.  

If the wind picks up or not, the mill voltage can not go past the battery voltage because they are connected directly.  But, the extra power has to go somewhere if the battery is in danger of being overcharged, usually a dump load like a heater.  The situation is not really related to the wind speeding up, more related to the fact that the battery is getting full.

#2  The generator design should make more power as the wind gets faster.

I am suprised they claim anything about being the only one to make more power in more wind. Check the output charts of the mills being made here, or any of the other manufacturers, more wind=more power.  

Big Time LOL.  Check the charts of mills made by guys on this site for power at 5mph and 10 mph wind, then compare that to a like size airX.  ("Jerry's" stuff for example, because he made some good charts, IMHO)  Does an Air X even produce any power or even start turning at 5mph?  At 10mph?

#3  Regulators and charge controllers are the same in my way of thinking for this RE stuff.  The maker can call it either one from what I see.  I call them all 'controllers'.

There are 3 basic ways to do it.

First, when the battery gets to say 13.8V, totally shut off the charge current, until the battery is down to say 13.7V then turn it on again.  This is more for solar panels. (series controller)

Second, feed all the amps to the battery until it gets to 13.8V, then bleed off just enough amps back to the 'charger' to hold the battery at 13.8V.  Again this is more for solar panels. (shunt controller)

Third, Feed all the amps to the battery. When the battery reaches 13.8V, an almost seperate device feeds basically battery amps to something else (dump load) like a water heater, until the battery voltage is 13.7V. This is more common for wind and water power. Almost a necessity for wind power.  It could be good for larger solar arrays, but isn't very common. (dump controller)

Then there are buck/boost controllers, mostly called Max Power Point Tracking, 'MPPT'.

There are Pulse Width Modulation, 'PWM', controllers that give max amps (P), but the time duration (W) of the amps is varied (M). A vastly improved variation of the series controller.

And for good measure, some controllers use a combination of them just to keep us reading the literature!

G-