Patent attributes
A secondary battery system capable of acquiring an SOC of a battery with a simple computation without acquiring battery characteristics is to be provided. The secondary battery system according to the present invention is adapted to acquire a momentary SOC (charging SOC) by obtaining an initial value of an SOC from a CCV acquired during a charging period and adding an integrated value of a charge or discharge current to the initial value of the SOC, acquire a momentary SOC (discharging SOC) by obtaining an initial value of an SOC from a CCV acquired during a discharging period and adding an integrated value of a charge or discharge current to the initial value of the SOC, and acquire an SOC close to a true value by averaging the charging SOC and the discharging SOC.