The voltage of the charging coil of an air-cooled diesel engine depends on the specific diesel engine model and design, usually between 12 and 24 volts. The charging coil is an important electrical component, which converts the alternating current generated by the generator into direct current through the principle of magnetic field induction, and provides a stable power supply for the electrical system of the diesel engine. If the voltage of the charging coil is insufficient or too high, it will affect the normal operation of the diesel engine. Therefore, it is very important to choose a charging coil that is suitable for the model and specification.