How do I make a battery that will charge using wind power? — K
Any rechargeable battery will do for this job, although I’d recommend using a lead-acid battery. To charge it, you need a wind-powered DC generator. You can make such a generator by attaching a DC motor to the blades of a fan and providing some weather-vane mechanism to ensure that the fan always points into the wind. The wind will then cause the fan to spin, and with it the motor. Wind energy will become mechanical energy and that will in turn become electric energy. The DC motor will act as a generator and will produce electric power.
To make this generator recharge the battery, you first need to ensure that the motor can generate a voltage that’s at least 20% higher than the voltage of the battery while the wind is blowing at its usual rate. If it can’t, you need a higher voltage motor or a lower voltage battery. Now you should connect the negative output wire of the generator to the negative terminal of the battery and use a power rectifier (a power diode) to connect the positive output wire of the generator to the positive terminal of the battery. You need this diode to prevent the battery from sending its power into the motor and making the fan turn when the wind isn’t blowing hard. If the fan starts turning when you’ve inserted the diode, you have it installed backward. When correctly inserted, the diode will prevent the battery from operating the fan so that the fan can only charge the battery. When the wind starts blowing and the fan starts turning, it will charge the battery.