The fast charging function of the car charging system needs the support of the car power supply in the car to be used normally, if the output power of the car power supply is not large enough, then even if the fast charging plug is used, the charging speed will be limited. Therefore, in the process of using the Xiaomi surging system to charge the car, it is necessary to first confirm whether the output power of the car power supply is enough, and try to avoid using other electrical appliances to charge at the same time, in order to make full use of the fast charging function and improve the charging efficiency.