Method and device for estimating charge/discharge electricity amount of secondary cell

An apparatus for estimating a charge/discharge electricity amount of a secondary battery, comprising:

• a current measurement part that measures current flowing through the secondary battery as current data,
• a voltage measurement part that measures a terminal voltage of the secondary battery as voltage data,
• a no-load voltage calculation part that obtains a plurality of pairs of data consisting of current data from the current measurement part and voltage data corresponding to this current data from the voltage measurement part, and that, in the case that specific selection conditions are satisfied, calculates a no-load voltage as a voltage intercept at a current of zero in a straight-line approximation obtained by statistical processing with respect to the plurality of pairs of data,
• an open circuit voltage calculation part that, in the case that specific current conditions or voltage conditions continue to be met for a certain amount of time, calculates an open circuit voltage from the terminal voltage of the secondary battery,
• a change-in-measured-voltage calculation part that calculates a change (ΔVb) in the no-load voltage or the open circuit voltage over a predetermined period of time, and
• an estimated charge/discharge electricity amount calculation part that calculates an estimated charge/discharge electricity amount (ΔQe) of the secondary battery based on the change in the no-load voltage or the open circuit voltage.