Good Morning
It is nice and chilly this morning, after an awesome day of wind. I was thrilled to see our wind turbine pump out 35 amps at 24 volts for much of the day. I had mentioned yesterday that the wind turbine wasn't oriented quite right, with what appeared to be a tendency to lean away from the wind while at rest. While the tail was indeed resting against the stop in normal velocity wind, the turbine would overcome this parked position in a faster wind and furl completely in the gusts above 40 mph.
What am I saying? Although it is apparent that changing the blade length has altered the physical charateristics of our turbine, it appears to me to be a change for the better. What should be done next depends of how much energy I want to put into the turbine. For instance, returning to a five foot blade length would make the blades face into the wind better. Shortening the blades by four to six inches could be as simple as lowering the turbine and sawing off the blade tips a little at a time until the blade wind seeking characteristic is better.
On the other hand we fell into this deal with the new sealed cell batteries and charging twice as many batteries is going to take considerably more power. With increased wattage in mind perhaps I should start building a new turbine frame with a greater yaw bearing to tower off-set, and increase the blade diameter accordingly. I'm guessing the large (2 inch) magnets we used in our design can handle a larger turbine, possibly up to 12 foot diameter.
Changing the blade length has provided me with a much greater understanding of the relationship of individual components of our wind turbine. Unless I missing something, we've tripled the output of our alternator by creating efficient blade design and still it survived the most powerful wind storm we had since we raised our turbine to the New Mexico sky. Sure it could have furled sooner, and I'm sure it would have been making more power in medium speed winds had the tail not been parked against the tower stop most of the time causing the turbine to be less than optimally oriented toward the wind.
All good lessons, and I'm happy I got to learn them with out the turbine burning up or blowing over. Also some new questions are arising in my mind, like: Lacking sophisticated electronics, how do I determine when the batteries are fully charged? I was in the shop working on my Isuzu Trooper diesel most of the day, so I got to monitor the three meters attached to the system.
There are two analog ammeters, one in-line with the output of the three full-wave bridge rectifiers feeding the six 12 volt 110AH flooded cell deep cycle batteries. The other ammeter is in-line between the batteries and the 600watt UPS we're using as an inverter. I've also got a Fluke multi-meter on the diversion load controller, monitoring the system voltage.
It notes in the Home brew wind power book that as the turbine voltage rises significantly above the battery voltage then current will flow into the batteries. I've never paid much attention to the actual voltage reading in a car charging system, although I do know that one simple tactic for quick trouble shooting a automotive charging system is switching on the headlights and increasing engine speed to see if the lights get brighter, indicating a functioning charger.
But the actual voltage as a automotive charger operating at full engine speed say for instance while driving, I'd have to guess and say the alternator brings the battery up from 12 volts to 18 volts. Our system operates at twice that voltage by placing two 12 volt batteries in series, creating 24 volts. 12 to 18 volts is an increase of 15%, so does it stand to reason that a 24 volt system would be increase to 36 volts? (24volts times 15%)
Well, whatever else happens with our wind turbine I think it is finally beginning to generate enough power that I'll be figuring out more about storage devices in the very near future. About as far as I've gotten so far is that if the turbine is putting out 20 amps, it is divided between however many batteries it is charging. The wind blows only consistently during the day and no I haven't seen it do much at night, just in case people we thinking that wind was 24/7, it isn't, at least not here. In fact yesterday was pretty much the first time I saw it spinning at or before dawn since we put the turbine up.
30 amps is better than 20 amps, and I saw the difference yesterday, while I worked in the shop I had the UPS running a computer which was installing service pack 3 while playing music and for the first time ever I was able to keep the 19 inch CRT on all day long and the battery voltage never dipped below 25 volts. Yippee!
This weekend Jona was working on some homework for his ongoing training as a journeyman commercial electrician, and coincidentally, he had a formula for determining pf (power factor) aka efficiency of a device. I don't know if I mentioned that I pulled a 3kw UPS out of storage in the barn to see about using it for an inverter. Well besides the fact that most of the knowledgeable folks at the OtherPower forums suggested that using an UPS as an inverter wasn't going to give adequate results, this particular UPS has only one 12 volt battery inside, and of course our system power is 24 volts.
Power Factor of a device is calculated by how much power goes in compared to how much comes out. Normally input or load is measured in VA (volt amps) and the output in Watts. So an electric motor may draw 5500 VA (220volts@25amps) and produce 3500 watts of usable power. Convert watts to horsepower 3500 watts equals ~4hp anyway in our example this motor would have a pf of .85 or 85 percent efficiency. These formulas work for all sorts of things in power generation. For instance determining how powerful a force needs to be to create energy at a given pf.
Interestingly, the huge UPS had a in-depth specs plate on the side, including a pf figure. What the spec plate on the rear of the 3kw UPS was confirming was that it has an awful Power Factor, so bad, indeed it makes a clear headed person wonder if back in 1996 when this monster was built power was free. 29% of the juice going into the UPS is lost due to inefficiency. My gods. Power may have been cheap to the designers of this UPS but it is quite hard to come by when one is pulling it out of the wind. Seventy one percent efficient, forget that.
Okay, speaking of batteries, I think it is time to go to the top of our ridge and check the water in the photovoltaic WiFi relay battery storage system, now that the sun is beginning to shine the system which has been down more than up this morning must be running low on power.
No problem, now that the Isuzu Trooper is all put back together with brand new nuts and bolts and super duper high temperature copper silicone gasket compound made specifically for turbocharger exhaust manifolds.
Yep, it was a magnificent day in the shop listening to wind powered music all day long.
I love this life,
