The battery charger is an electronic device for charging a rechargeable battery used in electric vehicles, power tools, video games, notebooks, digital and small portable electronic devices, and electronic appliances, and is generally composed of a casing, a power conversion portion, a charging detection portion, and a charging protection portion. Its output type is pure DC or pulsating DC. According to the connection method, it can be divided into wall-mounted and desktop. According to the type of rechargeable battery, it can be divided into nickel-cadmium battery charger, nickel-hydrogen battery charger, nickel-zinc battery charger, lead-acid battery charger, lithium battery charger and so on. According to the function of the charger, it can be divided into a dedicated charger and a universal charger.

Generally, first select the type, protection type, output voltage and current specification of the corresponding charger according to the type and voltage of the self-rechargeable battery, and then select the charger that meets the corresponding input conditions according to the voltage of the city network. It is best to use fully intelligent battery charger.