Texas Instruments Corporation

Evgenij Barsoukov

David Louis Freeman

Dan Russell Poole

The remaining run-time (t_rem) of a battery is determined independently of the condition of the battery and the amount of load on the battery by obtaining the value of a present total zero-current capacity (Qmax) of the battery based on relaxed-battery OCV values measured just before and just after a charging or discharging cycle. A current through the battery is integrated to determine a transfer of charge (Q) from the battery, and a value of total run-time (t_total) that would be required to reduce the open circuit voltage of the battery to a predetermined lower limit (Vmin) is determined. The remaining run-time (t_rem) is determined by subtracting the duration of the integrating from the total run-time (t_total).

Circuit and method for measurement of battery capacity fade

An internal impedance of a battery ( ) is automatically determined by operating a processor ( ) to analyze current flowing through the battery to determine if a transient condition due to change of current is occurring and determining when the transient condition has ended. A voltage of the battery is measured while a steady current is being supplied by the battery. The present depth of discharge (DOD) of the battery is determined and a database is accessed to determine a corresponding value of open circuit voltage. The internal impedance is computed by dividing the difference between the measured voltage of the battery and the open circuit voltage at the present DOD by an average value of the steady current. A remaining run-time of the battery can be determined using a total zero-current capacity of the battery, integrating the current to determine a net transfer of charge from the battery, determining a value of total run-time that would be required to reduce the voltage of the battery to a predetermined lower limit, determining the duration of the integrating, and determining the remaining run-time by subtracting the duration of the integrating from the total run-time.

Circuit and method for determining battery impedance increase with aging

A processor ( ) operates to determine amount of charge presently stored in a battery by determining that the battery is in a zero-current relaxed condition. Circuitry ( ) including a first ADC ( ) measures an open circuit voltage (OCV) of the battery prior to a period of time during which flow of current through the battery is not negligible. A program executed by the processor correlates the measured open circuit voltage (OCV ) with a corresponding value of the variable and selects the corresponding value as a value of the variable.

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Dallas, TX, United States of America

Evgenij Barsoukov