In this wind-powered battery charger circuit the dc motor is used as a generator. The voltage output is proportional to its rpm. The LTC1042 monitors the voltage output and provides the following control function.
1. if the voltage output is below 13.8V, the control circuit is active and the NiCad battery is charging through the LM334 current source. The lead-acid battery is not being charged.
2. if the voltage output is between 13.8V and 15.1V, the 12V lead-acid battery is being charged at about 1-amp/hour rate (limited by the power FET).
3. if generator voltage exceeds 15.1V (a condition caused by excessive wind speed or when the 12V battery is fully charged), the a fixed load is connected, which limits the generator rpm to prevent damage.
This wind powered charger can be used as a remote source of power where wind energy is plentiful, such as on sailboats or at remote radio repeater sites. Unlike solar-powered panels, this system will function in bad weather and at night.
Battery Charger Schematic using wind energy