Patent ID: 7630842

Claim:
A method for estimating a charging/discharging electricity amount of a rechargeable battery, the method comprising the steps of: measuring a data set of current flowing through the rechargeable battery and terminal voltage of the rechargeable battery corresponding to the current, and obtaining a plurality of the data sets; calculating a no-load voltage that is a voltage intercept of an approximate line at a zero-current state obtained through statistical processing using the plurality of data sets when a specific selection condition is satisfied; calculating an open-circuit voltage from the terminal voltage of the rechargeable battery when a specific current condition or voltage condition is satisfied continuously for a certain period of time; calculating a zero-current state voltage (Vzo) from the no-load voltage or the open-circuit voltage by selecting the no-load voltage as the zero-current state voltage when the specific selection condition is satisfied or by selecting the open-circuit voltage as the zero-current state voltage when the specific condition is not satisfied but the specific current condition or voltage condition is satisfied for the certain period of time; storing the zero-current state voltage; calculating a zero-current state voltage change amount (ΔVzo) during a period from when the zero-current state voltage is stored to when a zero-current state voltage is calculated subsequently; and calculating an estimated charging/discharging electricity amount (ΔQe) of the rechargeable battery based on the zero-current state voltage change amount.