Series battery pack self-balancing device capable of independently working in single string, and self-balancing battery cell

A series battery pack self-balancing device capable of independently working in a single string, each battery string in the series battery pack being provided with at least one self-balancing device for improving or maintaining the balanced state of the battery pack, wherein the self-balancing device is connected to positive and negative poles of the battery string through a conductor, the battery string provides a working voltage for the self-balancing device;

• the self-balancing device comprises a voltage detection unit, a timing unit and a discharging unit, wherein the voltage detection unit is used for detecting a voltage across the battery string, and comparing the voltage with a threshold voltage to output a comparison result, the timing unit is used for timing and outputting a timing result, and the discharging unit is used for discharging the battery string;
• the working process of the self-balancing device comprises the following steps:
• S1:
• after detecting that the voltage across the battery string is greater than the balancing starting threshold voltage VTHB by the voltage detection unit, starting discharging of the battery string by the discharging unit, and starting timing by the timing unit;
• and
• S2:
• stopping discharging by the discharging unit when the timing duration reaches a predetermined time Δt1.