Posts Tagged ‘Wind Generator’

Whether you build your own, or buy one, you will need some sort of controller for your wind turbine.

There are lots of charge controllers manufactured for solar and wind power systems. Any company that sells alternative energy stuff will have them. There are also always lots of them for sale on Ebay.

What’s a Charge Controller?

Basically, the general principle behind a charge controller is that it monitors the voltage of the batteries in your renewable energy system. The controller either sends power from your homemade wind generator into the batteries to recharge them, or diverts power coming from the wind generator to another place. This only occurs if the batteries are fully charged (to prevent over-charging and destroying the batteries).

We are assuming you are using a 12 volt battery system for the purposes of this discussion.

When your homemade wind generator is in operation, the wind generator is connected to the controller. Wires then run from the controller to the battery.

When you use power to run some appliance, say your TV, the power is then taken directly from the battery. If the battery voltage drops below 11.8 volts (you can set this on the controller), the controller switches the generator power to charging the battery. If the battery voltage rises to 14.5 volts (again, you have to set this), the controller switches to dumping the generator power into the dump load.

Usually, a water heater, or some other small device is used as a dump load. There are switches to adjust the voltage levels at which the controller changes between the two states of charging. A 11.8 and 14.5 volts as cut-in and cut-out voltages are recommended after consultation with battery experts.

There are two LED lights on the charge controller. When charging the battery, one LED is lit. When the power is being dumped to the other load the other light will be lit.

Usually the system runs pretty automatically and the LED lights gives us easy feedback on whether our renewable energy system is performing properly, and what it is doing right then. When the wind is really blowing more current goes into the batteries, which means more load on the generator. The system pretty much governs itself.

In a storm the force of the winds wind can get pretty dangerous. Switching the controller to dump power into the other load does a good job of braking the homemade wind generator and slowing it down.

Warning: the whole blade and hub assembly can swing around and knock you on the head if you are not very careful and the wind changes direction while you are working on it.

Next post: Wiring The Wind Generator. Stay tuned

Your homemade wind generator must be able to spin freely to face the wind at all times. The horizontal axis that the hub assembly sits on, must interact with the vertical axis of the tower in such a way that they are held secure, but will also spin to meet the wind direction.

You can use a simple bungee cord mounted between the pipe and the body of the generator to keep it from spinning around erratically and twisting up your charging wires. With a bit of plumbing supplies and some ABS (or PVC) pipe we can accomplish this goal quite quickly.

First we will assume that at the top of your tower is a vertical section of pipe. Your entire tower might be steel pipe that you have managed to find. Use at least 2 inch pipe for this purpose.

On top of this pipe, the wind generator assembly must sit, and be able to spin. We usually mount a simple flange assembly on the body of the wind generator for the pipe to fit into. Make sure that the flange holds at least 3 inches of the pipe from the tower, and that it will move easily. We do at times weld a 10 inch piece of pipe onto the flange for strength. It really depends on the wind generator size.

If you are building a wind generator more than 6 feet in blade diameter then add some more strength to the flange for safety.

The body of your homemade wind generator

First off locate a piece of ABS or PVC pipe that the DC motor would fit snugly into. This will depend on the size of the motor, but most will fit inside of a piece of 6 inch pipe quite nicely.

Cut the piece of pipe 2 inches longer than the DC motor. Next, you will fill the blade assembly end with a piece of wood with a hole cut in the centre so that the shaft of the motor can extend out. The shaft has to connect to the blade assembly eventually.

Before you put the DC motor inside this permanent weather shield you will need to attach the 3 inch flange to this piece of pipe. Keep the flange mount as close to the blade assembly as is practical. Consult with the Tilt-up assembly drawing below to make sure you get this part right.

Remember, the blade assembly is very heavy and you will want to balance the whole affair atop the pipe from the tower. A bit of experimentation will be necessary to achieve balance.

You should be able to find PVC fittings to reduce the 6 inch pipe that houses the DC motor down to a 3 inch pipe for the tail assembly. Attach the two together. A tail length of about 2 to 3 feet is quite adequate.

In our next post we will discuss how to build the tail.

If you want a complete blueprint on how to build a home made wind generator, check this site: Build a Homemade Wind Generator

Start by quartering a 48 inch long piece of pipe around its circumference and cutting it lengthwise into four pieces. You can check the post on How To Cut The Blades for this.

This will end up being a wind generator blade assembly of just over 8 feet in diameter. Adjust your lengths according to your own preferences.

Remember that you will need a blade diameter of approximately 8 feet to achieve an output of 1000 watts with a 20 mile per hour wind speed. A couple things you should remember though. The most important is the tremendous force the wind can place on your equipment if your blades are too big. Let’s assume a wind speed of 55 miles per hour, that’s really a common speed out there. If your wind generator blade assembly has a diameter of 3 feet the force on the blades is approximately 115 pounds. But, if you up that blade diameter to the 8 feet (we recommend for most projects) the force of the wind on your wind generator at a wind speed of 55 miles per hour is an incredible 840 pounds of force.

Now, your blades are not catching all of that force of course, but they are catching a great deal of it. We design our wind generators to handle these forces. Design your tower, blade and hub assembly with that in mind. Light is good for spinning, but strong is better. It is sometimes hard to strike the right balance, but new materials and sometimes some surprisingly old materials make the choices easier.

Attaching the blades to the hub

The pulley that makes up the central part of your hub assembly must fit tightly on the shaft of the DC motor. The hub assembly must spin the DC motor in order to produce power.

We usually drill a hole through the pulley and shaft and insert a small one eight of an inch bolt and nut to hold the two together.

On the pulley (hub) you will have to measure the circumference, or distance around the outside of the pulley. For a three blade assembly you will divide this number by 3 to give you the distance between the blade mounting pieces of steel.

The following diagram shows the placement of the steel on the hub for use with PVC blades.

Note: when using wooden blades make sure to use 1 inch angle iron so that the blades are mounted at an angle to the wind. We have found 1 inch by 2 inch works about the best. The blades should be mounted at an angle of about 10 degrees to the wind.

The steel should be drilled with a one quarter inch drill bit at the same position on the hub for each piece. This will vary depending on the hub material used. The above diagram gives you a good idea of how to do it. Keep the holes at least one inch in from the outside if possible for strength and they should just meet at the centre of the hub. Take your time during this process and you will have a wind generator that is well balanced and spins well. You will be glad you did.

Mounting the Blade Assembly on the DC motor

First we need to do a bit of testing to see if your blade assembly is balanced. Just place the whole thing on a shaft of similar size and give it a few spins.

Make a note of the place it stops each time. If you notice that the same blade is always facing down at the end of each spin, then it is a wee bit heavier. Just give it a quick trim until none of the blades consistently stops at the bottom.

You can now do a test mount of the blade assembly on the shaft of the DC motor.

In our next post we will cover how to build a mount for the DC motor. Stay tuned

This post is the third of a series of posts describing how to build a home made wind generator.

Check the first post on How To Build The Blades

Check the second post on What Materials To Use To Build The Blades

OK, Let’s get into how to cut the blades

Using a 4” to 12” sewer PVC pipe, you will cut it quartering the pipe, and then you will cut out one blade, and use it as a template for cutting out the others. That will leave you with 4 blades (3 plus one spare).We are going to build a 3 blade assembly. You can use a jigsaw to cut the pipe. See the figure below

Cutting the line with a jigsaw

The first step in cutting out the blades is to mark the pattern on the pipe with a marker. A tape measure and a large piece of project cardboard or Bristol board works great for transferring your pattern.

Notice that the centerline is slightly offset when cutting the first blade. This is to catch the wind more effectively. This first blade will be used as a template for the two other blades. See the figure below.

Notice that this example design pattern is set for a 10 inch pipe; in this way a 4 feet long blade will be on one side 7” wide and on the other 5”. If you use smaller or larger pipe diameter, just add or subtract one half inch of width for every 2 inches of pipe diameter as in the table below.

Pipe Diameter	Blade width at hub	Blade width at tip
4″	5.5″	3.5″
6″	6″	4″
8″	6.5″	4.5″
10″	7″	5″
12″	7.5″	5.5″

You can then do a little extra smoothing and shaping using a belt sander, palm sander or just sand paper on the cut edges to try to make them smoother. Smooth the sharp corners at the tip of the blades as well. This will serve to make the air flow better, thereby creating a better airfoil.

Wooden blades

Wood is also a recommended material to make blades and cedar is a nice wood. The Eastern White Cedar and Western Red Cedar have the same characteristics of lightness, super strength, flexibility and superb outdoor weathering capabilities.

For the building of your homemade wind generator blades you will want to find planed, finished lumber as thin as you can, preferably only one inch in thickness.

If you can’t find one inch lumber, ask at the lumber yard if they will cut it down to that size for you. The lumber piece should be 6 inches wide and 4 feet long for a single blade.

Use a jigsaw with a wood blade of fine teeth. Make each blade the same by copying the pattern 3 times.

Just put a small spacer piece on the leading side of each blade to tilt the blade in the direction of the wind. A slight tilt of 10 degrees is fine. Use a small piece of wood or angled metal to achieve the results you want to make that blade spin.

In our next post we will be discussing on how to build de hub that holds the blades together.

If you need a complete blueprint on how to build a home made wind generator CLICK HERE

If not, that´s Ok, just keep on checking our series of posts to get the whole picture to start your own project.

This is a walk trough to build a blade for your home made wind generator.

Your choice of blade design and material greatly affects your home made wind generator’s overall efficiency and performance. Most modern factory produced wind energy blades feature a 3 blade design with very slender blades made from space age materials mostly. Three blades work best to avoid vibration.

Those slender blades catch every bit of wind energy coming by too. You would think that the blades would have to be large in order to do this. But the most important aspect of blade design is how big of a diameter they form.

You will need a blade with outside diameter, measured to the tips, of at least 8 feet in order to achieve about 1000 watts of power production. If you don’t feel comfortable with this big of a machine then scale it back accordingly. Read more…

A 3 blade design can capture up to 8 horsepower of energy while many of the old bladed design will have a hard time producing 2 horsepower! All those blades get in the way of the wind moving through the blades and actually slow down the spin. This is what we regard as turbine efficiency.

Thankfully, the new materials and new blade design are available for us to take advantage from. These modern designs feature a high tip- speed ratio.

What is Tip-Speed Ratio?

Simply put, this is a comparison between angular velocity of the tip of wind generator blade and the wind speed.

Tip-Speed Ratio = Tip Speed / Wind Speed

Most of the newer models available today have a tip speed ratio of between 5:1 and 8:1. That is really moving. In other words, modern blades can rotate faster at lower wind velocities. The larger the number, the better efficiency in capturing wind energy.

This compares to the old slow moving water pumping windmills that used to dot the landscape with a tip speed ratio of around 1:1.

The old style windmills were designed to pump water, and although less efficient, they provided higher torque (because of the large blade outside diameter) and better performance at low wind speeds which gave them a steadier pumping action (more water delivered) in low wind situations. They had to start pumping immediately so they had to catch the wind at the start very effectively.

Build a Home Made Wind Generator
Click on the Image For Detailed Instructions

If you think of your wind generator blades as aircraft propellers you will gain a new appreciation for the intricate designs necessary to achieve this high overall efficiency at tip speeds that approach 125 miles per hour.

You do not need to replicate these technical advances to have an efficient machine. Just follow the simple directions for a smooth operating homemade wind generator.

Note that the most efficient aircraft propeller design is not the best design for a wind generator blade. The propeller is designed to move air, while the wind generator blade is designed to be moved by the air. Subtle differences exist which we will explain further.