The battery is a complex electrochemical system. When it runs under different load conditions or different ambient temperatures, the actual remaining capacity available for release is different; and as the battery's use time increases, its capacity will also decrease. Among the several battery residual capacity detection methods commonly used in recent years, the internal resistance method has the least impact on the system for batteries used online, and can be accurately measured throughout the battery life. Therefore, the internal resistance method is As an ideal method. However, under high noise conditions, it is found that the accuracy of the actual measured battery residual capacity is not satisfactory. Therefore, it is imperative to improve the online detection method of battery residual capacity under high noise conditions. On-line detection of the remaining capacity of the battery has a profound impact on the reliability of the entire power supply system. The remaining capacity of the battery is a problem that users are most concerned about, and it is closely related to the reliability of the entire power supply system. The higher the remaining battery capacity, the higher the system reliability.