Patent ID: 7688033
Filing Date: 2010-03-30
Classification: G01R,H02J

Abstract:
1. A method for detecting the state of a secondary battery, comprising: (a) a step of acquiring a plurality of data sets associating a current flowing through the secondary battery with a terminal voltage of the secondary battery corresponding to that current, wherein the plurality of data sets include (i) first data sets including first current data for the current in a charging direction and (ii) second data sets including second current data for the current in a discharging direction; (b) a step of making the plurality of data sets valid when specific selection conditions are satisfied; (c) a step of performing first statistical processing using the plurality of data sets including both the first data sets and the second data sets acquired during both charging and discharging, and calculating a first value of internal resistance in both the charging and discharging directions from the slope of a first linear approximation obtained by the first statistical processing; (d) a step of performing second statistical processing using first data sets acquired during charging, and calculating a second value of internal resistance in the charging direction from the slope of a second linear approximation obtained by the second statistical processing; and (e) a step of calculating a calculated value of internal resistance of the secondary battery based on the first value of internal resistance in both the charging and discharging directions and the second value of internal resistance in the charging direction.