Remaining electrical charge/remaining capacity estimating method, battery state sensor and battery power source system

An apparatus that estimates a remaining electrical charge or a remaining capacity of a battery that supplies power to a load, the apparatus comprising:

• a controller that uses an approximate exponential decay function including a plurality of exponential function terms of time and a plurality of coefficients;
• a charge circuit that stops a charge or discharge operation of the battery for a predetermined time;
• and
• a sensor that measures a voltage of the battery at a plurality of instances during the predetermined time, wherein
• the controller obtains a relationship between the voltage of the battery and time, determines the coefficients based on the obtained relationship between the voltage of the battery and the time, determines at least one power coefficient of an inferior logarithm of the exponential function terms by expressing the at least one power coefficient of the inferior logarithm of the exponential function terms as a predetermined function of temperature, and obtains an estimate of a stable open circuit voltage of the battery based on determined values of the coefficients.

A system comprising:

• a battery that supplies power to a load;
• a controller that uses an approximate exponential decay function including a plurality of exponential function terms of time and a plurality of coefficients;
• a charge circuit that stops a charge or discharge operation of the battery for a predetermined time;
• and
• a sensor that measures a voltage of the battery at a plurality of instances during the predetermined time, wherein
• the controller obtains a relationship between the voltage of the battery and time, determines the coefficients based on the obtained relationship between the voltage of the battery and the time, determines at least one power coefficient of an inferior logarithm of the exponential function terms by expressing the at least one power coefficient of the inferior logarithm of the exponential function terms as a predetermined function of temperature, and obtains an estimate of a stable open circuit voltage of the battery based on determined values of the coefficients.

A method for estimating a remaining electrical charge or a remaining capacity of a battery that supplies power to a load, the method comprising:

• using, at a controller of a battery system, an approximate exponential decay function including a plurality of exponential function terms of time and a plurality of coefficients;
• stopping, at the battery system, a charge or discharge operation of the battery for a predetermined time;
• measuring, at a sensor of the battery system, a voltage of the battery at a plurality of instances during the predetermined time;
• obtaining, at the controller of the battery system, a relationship between the voltage of the battery and time;
• determining, at the controller of the battery system, the coefficients based on the obtained relationship between the voltage of the battery and the time, wherein each of power coefficients of a natural logarithm of each of the exponential function terms is expressed as a temperature function including at least one coefficient, the coefficient of the temperature function of a first one of the power coefficients is determined in advance as a function of the coefficient of the temperature function of another of the power coefficients, and the determining includes determining the coefficient of the temperature function of the another of the power coefficients;
• and
• obtaining, at the controller of the battery system, an estimate of a stable open circuit voltage of the battery based on determined values of the coefficients.

An apparatus for estimating a remaining electrical charge or a remaining capacity of a battery that supplies power to a load, the apparatus comprising:

• a controller that uses an approximate exponential decay function including a plurality of exponential function terms of time and a plurality of coefficients;
• a charging circuit that stops a charge or discharge operation of the battery for a predetermined time;
• and
• a sensor that measures a voltage of the battery at a plurality of instances during the predetermined time, wherein
• the controller obtains a relationship between the voltage of the battery and time and determines the coefficients based on the obtained relationship between the voltage of the battery and the time,
• each of power coefficients of a natural logarithm of each of the exponential function terms is expressed as a temperature function including at least one coefficient, the coefficient of the temperature function of a first one of the power coefficients is determined in advance as a function of the coefficient of the temperature function of another of the power coefficients, and
• the controller further determines the coefficient of the temperature function of the another of the power coefficients, and obtains an estimate of a stable open circuit voltage of the battery based on determined values of the coefficients.

A system comprising:

• a battery that supplies power to a load;
• a controller that uses an approximate exponential decay function including a plurality of exponential function terms of time and a plurality of coefficients;
• a charging circuit that stops a charge or discharge operation of the battery for a predetermined time;
• and
• a sensor that measures a voltage of the battery at a plurality of instances during the predetermined time, wherein
• the controller obtains a relationship between the voltage of the battery and time and determines the coefficients based on the obtained relationship between the voltage of the battery and the time,
• each of power coefficients of a natural logarithm of each of the exponential function terms is expressed as a temperature function including at least one coefficient, the coefficient of the temperature function of a first one of the power coefficients is determined in advance as a function of the coefficient of the temperature function of another of the power coefficients, and
• the controller further determines the coefficient of the temperature function of the another of the power coefficients, and obtains an estimate of a stable open circuit voltage of the battery based on determined values of the coefficients.