Determination and control of battery state

A charge/discharge control apparatus for a secondary battery, comprising:

• a measuring means for measuring a terminal voltage, a charge/discharge current and a charge/discharge time of the secondary battery;
• memory means for storing said terminal voltage, said charge/discharge current and said charge/discharge time;
• control means for controlling a predestinated charge/discharge current which is to flow to and from, respectively, said secondary battery;
• and
• arithmetic means for arithmetically determining an open-circuit voltage, a polarization resistance thereof, a life cycle number, a residual charge/discharge time and a charge/discharge control voltage, respectively, of said secondary battery on the basis of said terminal voltage, said charge/discharge current, said predestinated charge/discharge current and said charge/discharge time.

An apparatus for storing electric energy, comprising:

• measuring means for measuring a terminal voltage, a charge/discharge current and a charge/discharge time of a secondary battery;
• memory means for storing said terminal voltage, said charge/discharge current and said charge/discharge time;
• control means for controlling a predestinated charge/discharge current which is to flow to and from, respectively, said secondary battery;
• arithmetic means for arithmetically determining an open-circuit voltage, a polarization resistance thereof, a life cycle number, a residual charge/discharge time and a charge/discharge control voltage, respectively, of said secondary battery on the basis of said terminal voltage, said charge/discharge current, said predestinated charge/discharge current and said charge/discharge time;
• and
• electric power conversion means for convening an AC electric power into a DC power, and for storing said DC power in said secondary battery.

An apparatus for measuring parameters of a secondary battery, comprising:

• means for measuring and storing a terminal voltage, a charge/discharge current and a charge/discharge time of said secondary battery in charge/discharge cycles of said battery;
• means for arithmetically determining an integrated power, an integrated charge quantity and an integrating time interval over a period extending from a start of a charge/discharge process to an end thereof in an immediately preceding cycle;
• means for determining a mean terminal voltage including a mean terminal voltage in a charging process and a mean terminal voltage in a discharging process by dividing said integrated power by said integrated charge quantity;
• means for determining a mean current including a mean charge current and a mean discharge current by dividing said integrated charge quantity by said integrating time interval;
• means for determining a polarization resistance of said secondary battery on the basis of said mean terminal voltage and said mean current by using a battery polarization resistance model;
• and
• means for determining an open-circuit voltage of said secondary battery on the basis of said polarization resistance.