Condition estimation device and method for battery

摘要

A condition estimation device for estimating condition of an electric storage device includes a voltage detector and a controller. A voltage measurement circuit (24) as the voltage detector is configured to detect a voltage (V) of a secondary battery (14) as the electric storage device. A BM (62) as the controller is configured to perform a distinctive point detection process to detect a distinctive point (P) based on the voltage (V) detected by the voltage measurement circuit (24), and an estimation process to estimate the condition of the secondary battery (14) (e.g., a battery capacity (X)) based on the distinctive point (P) detected in the distinctive point detection process. The distinctive point (P) is a point at which a variation in voltage per unit remaining capacity or per unit time (”V) of the secondary battery (14) during charge or discharge is a local maximum value. In this configuration, the condition of the secondary battery (14) (e.g., the battery capacity (X)) can be estimated without charging or discharging the secondary battery (14) until the secondary battery (14) satisfies a predetermined fully charged condition or fully discharged condition.