Distributed battery balance management method and battery system using this method

A distributed battery balance management method includes: performing a battery system balancing procedure by a battery system balance management unit and performing battery module balancing procedure by module balance management circuit (MBMC) of corresponding battery module (BM). The battery system balancing procedure includes: obtaining lowest module voltages of corresponding BMs; obtaining a lowest system voltage and an average system voltage of the battery system; determining whether the lowest module voltage of the corresponding BM is greater than the average system voltage; when yes, setting a balance time duty ratio of the corresponding MBMC as a first duty ratio; when no, setting the balance time duty ratio of the corresponding MBMC as a second duty ratio; and setting module balance enable signal of corresponding MBMC to be enable, thus allowing the corresponding BM to perform voltage balance control on the batteries in the corresponding BM.