Most car drivers have some basic knowledge about the electrical system of their vehicle; they know, for example, that the electricity used when the engine is not running is supplied from the battery and the battery also supplies energy required to start the vehicle. They also know that in turn, the starter motor will rotate the engine, causing the first spark in the plugs and consequent explosion of fuel, after which the machine starts to work regularly. While the engine is running, all of the electrical components are supplied with energy produced by the alternator. Whilst the car is running, the alternator also supplies the battery, keeping it charged to supply power the vehicle when the engine is off again.
The operation of the alternator, usually within a vehicle, is simple. An alternator can be easily acquired; making construction of a small wind turbine generator a perfect choice. The wind will supply the energy, either to be used immediately, or stored in batteries to use in the absence of the wind.
However, the car alternator may not be the ideal choice for this type of project; it requires a lot of energy to rotate the shaft of the alternator in order to reach sufficient revolutions per minute (RPM) to produce energy.
A direct connection of the turbine to the alternator could avoid the friction caused by belts in the transmission, if not for the need to multiply the speed of the alternator - which further aggravates the problem of effort, because to achieve the minimum RPM required for the production of electricity by the alternator there is the need for multiplication.
Just imagining ourselves riding a bike to understand idea of how resistance increases - when we change gears so that fewer chain turns produces more speed.
Step 2: The machine should be strong to endure the wind
One of the most important factors to consider when building a homemade wind generator is without a doubt its robustness and ability to withstand storms and high winds. No one will install such a device in a sheltered place, that would be a paradox - the wind turbine should be exposed (as much as possible) to the wind. However, we cannot disassemble the turbine and collect it when there are strong winds, which is natural at certain times of year. Therefore, it is necessary to build the machine so that it will endure not only with strong seasonal winds, but possible stormy phenomena that may occur.
The truth is that our machine is six years old, in a place that is often buffeted by strong winds and it seems like it has only just been placed there.
This means that with regards to robustness and safety of the machine, the construction was successful. Admittedly, it was built in a very peculiar way and perhaps very safely. This does not mean you should take ours as gospel, or that there are not other, better ways to build such a device. It should be noted that it can be very dangerous sitting next to a device that has not been built safely. Our opinion is that you should look not only at the most technical part of the project (the successful attainment of energy), but also to the strength of the system.
In the case of our generator, we believe we could have built the turbine diameter slightly larger, with wider and longer blades because of its strong structure. A larger turbine would have the advantage of generating more power, and running more easily in low wind conditions due to decreased resistance. We consider this to be a design error - easily fixed.
Step 3: Construction details of our wind generator
The strength of our wind generator starts right at the base. It is perfectly constructed upon a small foundation built of concrete, and the pole that supports the generator (not too high!) consists of a pipe of 20cm in diameter. This pipe was filled with concrete.
On top of this pole we attached a piece of iron pipe. This piece of pipe, about 30cm long, with a bearing at the bottom, will house another piece of pipe, namely the male, with the male tube having holes for bolts. This narrow tube is threaded inside the wider tube, which is then attached to the recycled alternator.
The turbine has a diameter of 1.35m, and is comprised of ten blades with a length of 0.45m by 0.15m wide. These blades are made of stainless metal from the interior of a dishwasher. A great advantage is that it doesn't nee to be painted, because it does not rust. The frame that supports the system consists of tubular metal rods, embedded in a piece of round tube which in turn is hooked to the shaft of the alternator. These metal rods pass at the base of the blades by means of a circular metal piece. This ratchet makes the metal rim of the rods that hold the blades, and the whole is further enhanced with galvanized iron wires arranged in a circle in the middle and at the tip of the blades.
The alternator was attached to the top tube, through an application to the belt tension and has a small metal cover to stay with some shelter from the sun or rain. With a crank, a piece of wood ,and some metal staples a system of brushes was improvised, to allow the current to pass through a cable and into the home.
Finally, I will talk about the rear of the turbine - the turbine advisor. This element was produced from the sheet metal of the same dishwasher. It is screwed to a square piece of iron, resting on a piece of round tube, allowing placement at an angle of 90 degrees with the turbine. This allows the turbine to receive the wind from the front or laterally, turning to suit the best angle.
All materials used in the construction of wind generator, with the exception of the cement, were recovered scraps.