[email protected]
A Publication of the FREE Wind Press - May be re-printed for personal use only
Copyright (C) 2007 TRUE-NORTH Power Systems
For commercial or non-profit publication contact TRUE-NORTH Power Systems
Lion's Head ON N0H 1W0 - (519) 793-3290
A Publication of the FREE Wind Press - May be re-printed for personal use only
Copyright (C) 2007 TRUE-NORTH Power Systems
For commercial or non-profit publication contact TRUE-NORTH Power Systems
Lion's Head ON N0H 1W0 - (519) 793-3290
Issue 1:3 Headlines: March 2003
Where's the AMTV?
Testing wind turbines takes patience because the wind does not always cooperate and waiting for the right wind conditions can take a long time. Sometimes you have to wait till next season or move everything to someplace where the conditions are right. So, in 1999 and 2000 AEROMAX developed an "Accelerated Mission Test Vehicle" or AMTV. THis vehicle can quickly generate the wind speed and duration needed for rapid design development. It can also easily move an entire test program to just the right altitude or weather conditions that are needed. As a result, it quickly became an essential part of the AEROMAX blade and turbine design program.
LAKOTA and OB1KW testing.
All AEROMAX products undergo extensive instrumented testing evaluate performance and validate engineering predictions The Accelerated Mission Test Vehicle (AMTV) pictured below, was used in development and pre-production testing of both the LAKOTA and the OB1KW turbines. Manned by accredited Aerospace Engineers, this vehicle carried state-of-the-art test, and data logging computers for capturing real-time, atmospheric and matching performance data. Unfortunately the technology was so interesting that the truck with all of its instrumentation and a LAKOTA turbine was stolen in May 2001 just as they completed the LAKOTA trials but before the OB1KW was ready for production. Even so, the OB1KW program had already logged several hundred "flight test" hours, which was enough to achieve the final blade iteration.
Testing wind turbines takes patience because the wind does not always cooperate and waiting for the right wind conditions can take a long time. Sometimes you have to wait till next season or move everything to someplace where the conditions are right. So, in 1999 and 2000 AEROMAX developed an "Accelerated Mission Test Vehicle" or AMTV. THis vehicle can quickly generate the wind speed and duration needed for rapid design development. It can also easily move an entire test program to just the right altitude or weather conditions that are needed. As a result, it quickly became an essential part of the AEROMAX blade and turbine design program.
LAKOTA and OB1KW testing.
All AEROMAX products undergo extensive instrumented testing evaluate performance and validate engineering predictions The Accelerated Mission Test Vehicle (AMTV) pictured below, was used in development and pre-production testing of both the LAKOTA and the OB1KW turbines. Manned by accredited Aerospace Engineers, this vehicle carried state-of-the-art test, and data logging computers for capturing real-time, atmospheric and matching performance data. Unfortunately the technology was so interesting that the truck with all of its instrumentation and a LAKOTA turbine was stolen in May 2001 just as they completed the LAKOTA trials but before the OB1KW was ready for production. Even so, the OB1KW program had already logged several hundred "flight test" hours, which was enough to achieve the final blade iteration.
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Although neither local law enforcement nor the FBI ever located anything but a few pieces of test equipment, the software chip containing their new Pulse-Width Modulated Controller (first tested in 2000) was not installed at the time and as a result their key pre-patented technology was not compromised.
A very well instrumented testing configuration was installed behind the cab and with a technician in the back, it was not uncommon for this rig to be seen rolling down the Arizona highways at 2 o'clock in the morning taking measurements.
In early 2000 AEROMAX began advertising that the OB1KW, a larger 1KW machine, would be COMING SOON! and they began advertising in popular magazines such as Home Power. The OB1KW is a 1Kw producer at 18mph which means at 25-28mph where many small turbines are rated it produces over 2Kw. With a larger nearly 10ft diameter blade array it's peak power is in excess of 3.5Kw.For those who think this was just vapour-ware I can assure you this advanced blade design, pulse-width modulated, turbine does exist. Below are a couple of actual photographs, the first photo was taken just 3 months ago in Dec 02, and it has completed most of its development trial in preparation for going into production. The second is a rare photo of it on the test truck in daylight just weeks before the truck disappeared. As a cash flow managed company, however, AEROMAX has chosen to fund the OB1KW production out of LAKOTA world wide sales. This is why the priority has been focused on LAKOTA over the past 18-20 months.
You may remember seeing the OB1KW ad on the right in late 2001. If you go to the OB1KW Gallery you can see pictures of the prototype in test. Although no date is promised yet we expect the OB1 to still be ground breaking technology and a new small turbine design point when it is finally released.
Go to OB1KW Gallery
A very well instrumented testing configuration was installed behind the cab and with a technician in the back, it was not uncommon for this rig to be seen rolling down the Arizona highways at 2 o'clock in the morning taking measurements.
In early 2000 AEROMAX began advertising that the OB1KW, a larger 1KW machine, would be COMING SOON! and they began advertising in popular magazines such as Home Power. The OB1KW is a 1Kw producer at 18mph which means at 25-28mph where many small turbines are rated it produces over 2Kw. With a larger nearly 10ft diameter blade array it's peak power is in excess of 3.5Kw.For those who think this was just vapour-ware I can assure you this advanced blade design, pulse-width modulated, turbine does exist. Below are a couple of actual photographs, the first photo was taken just 3 months ago in Dec 02, and it has completed most of its development trial in preparation for going into production. The second is a rare photo of it on the test truck in daylight just weeks before the truck disappeared. As a cash flow managed company, however, AEROMAX has chosen to fund the OB1KW production out of LAKOTA world wide sales. This is why the priority has been focused on LAKOTA over the past 18-20 months.
You may remember seeing the OB1KW ad on the right in late 2001. If you go to the OB1KW Gallery you can see pictures of the prototype in test. Although no date is promised yet we expect the OB1 to still be ground breaking technology and a new small turbine design point when it is finally released.
Go to OB1KW Gallery
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Blade Design.
The design of wind turbine blades is critical to the efficiency of a turbine. The right number, shape, orientation, material, stiffness and surface of the blade determines how well it performs. In addition, blades cannot be optimized for all wind conditions. Blades that work efficiently at low speed will not likely perform well in high winds. That's why "Windmills" have many paddle like blades to pump water slowly while "Wind Turbines" have fewer thinner blades designed to move faster to generate electricity. Those machines that are designed for various wind conditions usually have more complex mechanisms to "feather" of change the pitch angle of the blades as conditions warrant.
So what kind of blades work best? This discussion will specifically avoid the engineering formulas and complex mathematics that determines blade, and therefore turbine efficiency, so for all you backyard tinkerers and professional engineers sorry, but some people just want to understand what to look for and don't really want enough information to know how to design blades. Blades have a number of critical dimensions or parameters that control their ability to capture energy from the wind. First and foremost is size. In general, size matters above all else. I say in general because smaller blades can out perform larger inefficient designs to a point, but if you make the blades larger you'll have more total energy to capture and efficiency is less important. The width (Chord) and thickness of the blade profile also contributes, but that depends heavily on the shape of the profile. Also a blade of constant chord will not be as efficient as one that tapers from root (near the hub) to tip.
As the blades rotate they pass though the horizontal column of air coming toward it. The air passes over the this airfoil like the wing of a plane. The speed of the air passing over the tip of the blade is much faster than over the root. That's because the tip is moving faster than the root as it rotates. The tip has to travel a farther distance in each rotation. As a result, it will reach it's critical "stall speed" sooner than the root part of the blade, so it must not be at the same angle at the root to operate efficiently. That's why you see a "twist" in the blade. Not twisted?, then most of the blade is not providing optimum lift most of the time. Also, if it has a constant chord, that is, it has the same "width" from root to tip, it cannot provide low startup speed or optimum efficiency at root and tip at the same time, because all parts of the blade are travelling at different speeds through the air, all the time. It needs to be tapered both in chord and thickness from root to tip.
One of the most important factors to blade efficiency is Tip Speed Ratio or (TSR). That's the ratio of the speed of the blade tip going through the air in relation ot the actual speed of the wind going through the rotor. At ratios above 10 or 11 to 1 (10:1 or 11:1) the blade is very near if not beyond the the upper limit of it's efficient range. The closer you can get to that point where efficiency drops off the better because the faster the rotation speed the more electrons you can move and the more watts you produce. Simple constant chord, non-twisted blades reach the upper limit of the most efficient TSR well before the more advanced blades, but if you design everything bigger you don't have to be as efficient to make the same amount of energy. Conversely, if you can make a very efficient blade you can keep the machine smaller and lighter and still produce the desired power level. Some old timers would say the bigger and heavier the better. It will last longer if it moves slower tehy argue. However, modern materials and good design make long lasting blades and generators that produce more power with less effort and size. . . and they are easier to handle without a crain.
The wind energy pushing on the blades is resisted by the stiffness of the blade as it forces the air to go around and over the surfaces. If the blade is made of wood or plastic, even metals they flex in response to the wind. This flexing is sometimes helpful in high winds because to "spills" energy that the turbine can't harvest in it's power range. That's because it was designed for a specific wind speed. Very stiff blades will carry the load from root to tip and can extract more energy per square foot, for a given size blade. If they are made from carbon fiber strands that run the length of the blade then they will retain both stiffness and light weight characteristics. Many blades advertise as having "Carbon fiber" but these are often only carbon black particles in a plastic resin base. True carbon fiber is made of long strands of carbon that become extremely stiff when pressure treated within a hardened epoxy material. Flexible blades, generally waste energy and can crack from material fatigue from constant flexing as they turn. In addition, the "tip flutter" this produces at the ends of the blade is often the main cause of noise that many people worry about with regard to wind turbines. Properly designed blades should be virtually silent, with a barely audible swishing sound from downwind in normal operation.
Also important is the shape of the blade tip. It should be tapered and rounded from the leading edge to trailing edge as well as gently swept from front to back. This allows the fastest moving air to depart from the blade tip with the least resistance and turbulence. As a result, there is less of a turbulent tip-vortex generated and less noise produced by the smoother airflow.
So in summary, blades come in all shapes, sizes and numbers. An efficient blade array has three blades that are tapered, twisted and have a sculptured shape across the entire airfoil. The tips should be swept from leading edge to trailing edge with a smoothly rounded end edge. Light weight and high stiffness will extract more energy at most wind speeds and also take more advantage of transient energy available in short duration gusts. Blade design is complex in it's technology and engineering but the fundamental features of an inefficient design are easy to spot. A flexible, constant chord size, non-twisted blade with square tips and blunt leading edge will make more noise and will not be efficient in capturing energy from the wind. Also, being flexible, it is more likely to crack, break or wear out prematurely.
The design of wind turbine blades is critical to the efficiency of a turbine. The right number, shape, orientation, material, stiffness and surface of the blade determines how well it performs. In addition, blades cannot be optimized for all wind conditions. Blades that work efficiently at low speed will not likely perform well in high winds. That's why "Windmills" have many paddle like blades to pump water slowly while "Wind Turbines" have fewer thinner blades designed to move faster to generate electricity. Those machines that are designed for various wind conditions usually have more complex mechanisms to "feather" of change the pitch angle of the blades as conditions warrant.
So what kind of blades work best? This discussion will specifically avoid the engineering formulas and complex mathematics that determines blade, and therefore turbine efficiency, so for all you backyard tinkerers and professional engineers sorry, but some people just want to understand what to look for and don't really want enough information to know how to design blades. Blades have a number of critical dimensions or parameters that control their ability to capture energy from the wind. First and foremost is size. In general, size matters above all else. I say in general because smaller blades can out perform larger inefficient designs to a point, but if you make the blades larger you'll have more total energy to capture and efficiency is less important. The width (Chord) and thickness of the blade profile also contributes, but that depends heavily on the shape of the profile. Also a blade of constant chord will not be as efficient as one that tapers from root (near the hub) to tip.
As the blades rotate they pass though the horizontal column of air coming toward it. The air passes over the this airfoil like the wing of a plane. The speed of the air passing over the tip of the blade is much faster than over the root. That's because the tip is moving faster than the root as it rotates. The tip has to travel a farther distance in each rotation. As a result, it will reach it's critical "stall speed" sooner than the root part of the blade, so it must not be at the same angle at the root to operate efficiently. That's why you see a "twist" in the blade. Not twisted?, then most of the blade is not providing optimum lift most of the time. Also, if it has a constant chord, that is, it has the same "width" from root to tip, it cannot provide low startup speed or optimum efficiency at root and tip at the same time, because all parts of the blade are travelling at different speeds through the air, all the time. It needs to be tapered both in chord and thickness from root to tip.
One of the most important factors to blade efficiency is Tip Speed Ratio or (TSR). That's the ratio of the speed of the blade tip going through the air in relation ot the actual speed of the wind going through the rotor. At ratios above 10 or 11 to 1 (10:1 or 11:1) the blade is very near if not beyond the the upper limit of it's efficient range. The closer you can get to that point where efficiency drops off the better because the faster the rotation speed the more electrons you can move and the more watts you produce. Simple constant chord, non-twisted blades reach the upper limit of the most efficient TSR well before the more advanced blades, but if you design everything bigger you don't have to be as efficient to make the same amount of energy. Conversely, if you can make a very efficient blade you can keep the machine smaller and lighter and still produce the desired power level. Some old timers would say the bigger and heavier the better. It will last longer if it moves slower tehy argue. However, modern materials and good design make long lasting blades and generators that produce more power with less effort and size. . . and they are easier to handle without a crain.
The wind energy pushing on the blades is resisted by the stiffness of the blade as it forces the air to go around and over the surfaces. If the blade is made of wood or plastic, even metals they flex in response to the wind. This flexing is sometimes helpful in high winds because to "spills" energy that the turbine can't harvest in it's power range. That's because it was designed for a specific wind speed. Very stiff blades will carry the load from root to tip and can extract more energy per square foot, for a given size blade. If they are made from carbon fiber strands that run the length of the blade then they will retain both stiffness and light weight characteristics. Many blades advertise as having "Carbon fiber" but these are often only carbon black particles in a plastic resin base. True carbon fiber is made of long strands of carbon that become extremely stiff when pressure treated within a hardened epoxy material. Flexible blades, generally waste energy and can crack from material fatigue from constant flexing as they turn. In addition, the "tip flutter" this produces at the ends of the blade is often the main cause of noise that many people worry about with regard to wind turbines. Properly designed blades should be virtually silent, with a barely audible swishing sound from downwind in normal operation.
Also important is the shape of the blade tip. It should be tapered and rounded from the leading edge to trailing edge as well as gently swept from front to back. This allows the fastest moving air to depart from the blade tip with the least resistance and turbulence. As a result, there is less of a turbulent tip-vortex generated and less noise produced by the smoother airflow.
So in summary, blades come in all shapes, sizes and numbers. An efficient blade array has three blades that are tapered, twisted and have a sculptured shape across the entire airfoil. The tips should be swept from leading edge to trailing edge with a smoothly rounded end edge. Light weight and high stiffness will extract more energy at most wind speeds and also take more advantage of transient energy available in short duration gusts. Blade design is complex in it's technology and engineering but the fundamental features of an inefficient design are easy to spot. A flexible, constant chord size, non-twisted blade with square tips and blunt leading edge will make more noise and will not be efficient in capturing energy from the wind. Also, being flexible, it is more likely to crack, break or wear out prematurely.
LAKOTA To Be Seen on the Featured Environmental Home Display
National Home Show 4-13 April 03
Toronto - Exhibition Place
TRUE-NORTH Power Systems and the LAKOTA SC wind turbine will be part of the Featured display called Home Alive! The House that Thinks, Drinks and Breathes will be fully constructed as a Feature Model at the 2003 National Home Show in Toronto, from April 4th to 13th, 2003. Read all about Home Alive!
This is a first for sustainable home ideas. Over 300,000 visitors over 10 days will have the opportunity to learn about the many unique Home Alive! features. This innovative modular straw bale home will be fully constructed inside the conference centre at the CNE grounds in Toronto and contain hundreds of environmental and energy saving products and building techniques.
Come see the LAKOTA first hand and receive a substantial cash back offer if it is purchased at the show.
After the National Home Show, Home Alive! will be disassembled, then rebuilt at the non-profit Everdale Environmental Learning Centre, one hour north-west of Toronto. By fall of 2003, Home Alive! will accept its first live-in tenants and re-open its doors for monthly tours and real-time internet virtual tours, providing the public with on-going opportunities to learn about the most current and appropriate living ideas in Canada.
Designed and built by Ben Polley of Harvest Homes together with landscape architecture by Brad Peterson. The Home Alive! project will incorporate numerous planet-friendly building, product and living systems ideas. One of the few places you'll be able to see these ideas, all in one place and working together.
Come see the new LAKOTA SC turbine . . up close.
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National Home Show 4-13 April 03
Toronto - Exhibition Place
TRUE-NORTH Power Systems and the LAKOTA SC wind turbine will be part of the Featured display called Home Alive! The House that Thinks, Drinks and Breathes will be fully constructed as a Feature Model at the 2003 National Home Show in Toronto, from April 4th to 13th, 2003. Read all about Home Alive!
This is a first for sustainable home ideas. Over 300,000 visitors over 10 days will have the opportunity to learn about the many unique Home Alive! features. This innovative modular straw bale home will be fully constructed inside the conference centre at the CNE grounds in Toronto and contain hundreds of environmental and energy saving products and building techniques.
Come see the LAKOTA first hand and receive a substantial cash back offer if it is purchased at the show.
After the National Home Show, Home Alive! will be disassembled, then rebuilt at the non-profit Everdale Environmental Learning Centre, one hour north-west of Toronto. By fall of 2003, Home Alive! will accept its first live-in tenants and re-open its doors for monthly tours and real-time internet virtual tours, providing the public with on-going opportunities to learn about the most current and appropriate living ideas in Canada.
Designed and built by Ben Polley of Harvest Homes together with landscape architecture by Brad Peterson. The Home Alive! project will incorporate numerous planet-friendly building, product and living systems ideas. One of the few places you'll be able to see these ideas, all in one place and working together.
Come see the new LAKOTA SC turbine . . up close.
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LAKOTA Photo Gallery?
There have been many requests to see more LAKOTA picture in actual installations. There is now a new LAKOTA Photo Gallery in the website. Just go to the Products page and click on Turbine features or performance and you'll find a link called "Show me Photos". There are lots of close ups and some typical installation photos from Canadian and US LAKOTA sites. Ask how your LAKOTA Installation can be added to the Gallery.
There have been many requests to see more LAKOTA picture in actual installations. There is now a new LAKOTA Photo Gallery in the website. Just go to the Products page and click on Turbine features or performance and you'll find a link called "Show me Photos". There are lots of close ups and some typical installation photos from Canadian and US LAKOTA sites. Ask how your LAKOTA Installation can be added to the Gallery.
Ontario Energy Goes "off the clock" in Feb
During late Feb and early March the "Spot Price" of energy was so high it "FLAT LINED" across the top of the daily rate chart that maxes out at 20 cent per KwHr. This record setting demand was paid for by importing energy from other provinces and the US. As a result your next power bill will push off those actual costs for another month and ignore the real cost of energy for the short term. . . but someday we'll have to pay for what we use today. It wasn't free energy when it was used and someday we'll ahve to pay for it. The Ontario government buys it at spot price and sells it to you for 4.3 cents until 2006. That deficit is building up in our Ontario Hydro Debt. . . . .that each of us pays every month by the way . . . . check your hydro bill.
I write this, 21 Mar 03 the cost of energy in Ontario is:
Current Market Demand: 20,363 MW Current Hourly Price (HOEP): $137.43 /MWh (13.74¢/kWh) at 08:00 p.m. EST March 20 Average Price Since May 1: $58.14 /MWh (5.81¢/kWh) Hourly Uplift Charge Estimate: $9/MWh (0.9¢/kWh) at 08:00 p.m.
The chart below is published along with all other Ontario real-time and historical data by the IMO (Independent Electricity Marketing Operator)of Ontario. They operate like an electrical energy "Stock Exchange" and buy and sell energy as supply and demand fluctuates.
They calculate it in "Cents/Megawatt" but 1.30 cents/ megawatt = 0.13 cents/Kilowatt so you can see from the chart the median price level is about 13 cents. Don't forget, this is just the SPOT price. The REAL cost is the number that comes from dividing your KwHrs used by the total amount you paid. That's the number that really counts, regardless of any "price freeze". But then, if you are interested in Wind Energy, you already knew that.
[missing image]
During late Feb and early March the "Spot Price" of energy was so high it "FLAT LINED" across the top of the daily rate chart that maxes out at 20 cent per KwHr. This record setting demand was paid for by importing energy from other provinces and the US. As a result your next power bill will push off those actual costs for another month and ignore the real cost of energy for the short term. . . but someday we'll have to pay for what we use today. It wasn't free energy when it was used and someday we'll ahve to pay for it. The Ontario government buys it at spot price and sells it to you for 4.3 cents until 2006. That deficit is building up in our Ontario Hydro Debt. . . . .that each of us pays every month by the way . . . . check your hydro bill.
I write this, 21 Mar 03 the cost of energy in Ontario is:
Current Market Demand: 20,363 MW Current Hourly Price (HOEP): $137.43 /MWh (13.74¢/kWh) at 08:00 p.m. EST March 20 Average Price Since May 1: $58.14 /MWh (5.81¢/kWh) Hourly Uplift Charge Estimate: $9/MWh (0.9¢/kWh) at 08:00 p.m.
The chart below is published along with all other Ontario real-time and historical data by the IMO (Independent Electricity Marketing Operator)of Ontario. They operate like an electrical energy "Stock Exchange" and buy and sell energy as supply and demand fluctuates.
They calculate it in "Cents/Megawatt" but 1.30 cents/ megawatt = 0.13 cents/Kilowatt so you can see from the chart the median price level is about 13 cents. Don't forget, this is just the SPOT price. The REAL cost is the number that comes from dividing your KwHrs used by the total amount you paid. That's the number that really counts, regardless of any "price freeze". But then, if you are interested in Wind Energy, you already knew that.
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What's a Charge Controller?
A Charge Controller monitors your turbine or solar PV output and battery voltage. As the voltage rises it watches a preset limit and activates a "diversion load" to dump excess energy that cannot be stored. It also watches to see if the battery voltage is getting too low and when it does it can signal a relay to isolate the battery bank from over discharge. I can't say I have a lot of experience using various manufacturers equipment so I won't try and compare features and benefits, but using the Trace C-40 as an example I can discuss what to look for.
The Trace "C" series charge controllers have a good combination of features for most applications. These are voltage selectable 12, 24, 48v with the ability to optimize it's charging for Lead Acid, NiCad or Gel type batteries. They also have a manual or automatic low voltage switching ability and a manual reset for low voltage operations. Reverse polarity protection is useful and a three stage battery charging method will keep your batteries healthy for a longer time than the more simple chargers that only have one stage. The C series also have the ability to plug in an optional temperature sensor that will limit the top charge voltage based on the temperature of the batrtery, during equalization charging that is done usually once a month to improve absorption.
This may sound like a bit of a sales pitch for Trace but I have not come across other suppliers out there that can do the same job in a small silent package for around $300CDN. If you know one please send me an email and we'll try and do some comparison testing when we get the FREE Wind Test Centre running in a few months. Charge control is essential for long battery life and most good quality deep charge batteries like Surrette or Trojan will last 15+ years with good charge control. That's important if you are going to spend $5,000 or more on a 1000 amphrs of capacity. And diversion control is just as essential for protecting your wind turbine if you have no place to store energy when your batteries are full.
Quality, true sine-wave inverters like Trace and Outback do have built in Charge Control with temperature sensor input and multi-replay control of AC diversion power but they can cost several thousand dollars more than needed if you're running a small remote wind system with limited storage capacity.
A Charge Controller monitors your turbine or solar PV output and battery voltage. As the voltage rises it watches a preset limit and activates a "diversion load" to dump excess energy that cannot be stored. It also watches to see if the battery voltage is getting too low and when it does it can signal a relay to isolate the battery bank from over discharge. I can't say I have a lot of experience using various manufacturers equipment so I won't try and compare features and benefits, but using the Trace C-40 as an example I can discuss what to look for.
The Trace "C" series charge controllers have a good combination of features for most applications. These are voltage selectable 12, 24, 48v with the ability to optimize it's charging for Lead Acid, NiCad or Gel type batteries. They also have a manual or automatic low voltage switching ability and a manual reset for low voltage operations. Reverse polarity protection is useful and a three stage battery charging method will keep your batteries healthy for a longer time than the more simple chargers that only have one stage. The C series also have the ability to plug in an optional temperature sensor that will limit the top charge voltage based on the temperature of the batrtery, during equalization charging that is done usually once a month to improve absorption.
This may sound like a bit of a sales pitch for Trace but I have not come across other suppliers out there that can do the same job in a small silent package for around $300CDN. If you know one please send me an email and we'll try and do some comparison testing when we get the FREE Wind Test Centre running in a few months. Charge control is essential for long battery life and most good quality deep charge batteries like Surrette or Trojan will last 15+ years with good charge control. That's important if you are going to spend $5,000 or more on a 1000 amphrs of capacity. And diversion control is just as essential for protecting your wind turbine if you have no place to store energy when your batteries are full.
Quality, true sine-wave inverters like Trace and Outback do have built in Charge Control with temperature sensor input and multi-replay control of AC diversion power but they can cost several thousand dollars more than needed if you're running a small remote wind system with limited storage capacity.
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