A Wind Energy-Powered Charger

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Electrical Circuit

The simplest form of charging system for Breezy could be formed by directly connecting the motor/generator to the battery through a diode. With this system, the diode allows power generated by the motor/generator to be applied to the battery, but blocks any power trying to return from the battery. Without the diode, the battery would rapidly discharge itself back into the motor during times of low or no wind. However,

I don't recommend this charging system. With the 40:1 step-up mechanism attached to the motor/generator, voltages as high as 10 volts can be created in high-wind conditions. These high voltages would overcharge the 1.5 volt batteries and could possibly damage them. Instead you will need to add a couple of other components to limit the amount of power made available to the battery. Refer to

Figure 2

and notice the motor/generator is connected through the 1 N4007 diode and the 51 ohm, one watt resistor, to the battery holder. These parts are available from your local Radio Shack store (or see Editor's Note to order parts). In addition to the diode and resistor, a special type of transistor (Field Effect Transistor) is utilized to limit the amount of power in the circuit. When the windspeed increases above the optimum level needed for charging, the motor/generator output voltage increases above three volts

The Field Effect Transistor senses this voltage increase and begins to dissipate the extra electrical energy as heat. Additionally, the 51-ohm resistor limits the amount of charging current applied to your batteries to keep them charging properly. If the wind gusts strongly, the transistor will continue to clamp the charging voltage harder and harder until it eventually "slips" the rubber drive band temporarily. This action will not harm the unit, but rather acts like a governor on the system. The LED (Light Emitting Diode) is an option that you can add to Breezy that gives you a visual "OK" indication. Building the circuit is easy. Using a small soldering iron, simply connect the various parts. Keep your work neat and remember that you will need to install the circuit in the battery box later. Remember to

use red wire on the positive side, black on the negative. If not, you might uncharge a battery and damage it. Using a small voltmeter, check the polarity of your motor/generator. With the wind blowing, the rotor turning, and the motor/generator outputting a voltage, determine which lead or terminal is positive, and which is negative.

If you don't connect the positive side to the diode, the unit won't charge; double-check this on your Breezy. Congratulations, you're now done with the electrical part as well.

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