Method and apparatus for determining battery life

• US 20020161537A1
• Filed: 04/26/2002
• Published: 10/31/2002
• Est. Priority Date: 04/27/2001
• Status: Active Grant

• Current Assignee: Lenovo PC International Limited (Lenovo Group Ltd.)
• Original Assignee: International Business Machines Corporation
• Inventors: Odaohhara, Shigefumi
• Granted Patent: US 6,842,708 B2
• Time in Patent Office: Days
• US Class Current: 702/63
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables
• CPC Class Codes: G06F 1/28 Supervision thereof, e.g. detecting power-supply failure by out of limits supervision

Abstract

Disclosed is a method and apparatus for determining and communicating the life of a battery which is repeatedly charged and discharged while providing power to one of various types of applicable electronic devices. The intelligent battery is provided with a current measurement circuit for measuring charge current while the battery is charged, a battery charge stop circuit for stopping the battery charge, a voltage measurement circuit for measuring the battery voltage of the battery while charged while charge is stopped. The present invention also contemplates a CPU for computing an internal impedance in accordance with the measured battery voltage and charge current under charge and the battery voltage while charge is stopped, and an embedded controller for determining the life of the battery in accordance with the information about the internal impedance transmitted from the CPU through a communication line. Finally, information about the battery life can be displayed or delivered to a user at a predetermined time or continuously during use.

Claims

1. An electrical apparatus having a body which consumes power and a battery for supplying power to the body by charge and discharge, comprising:

a current value measurement unit for measuring a constant current value when charging or discharging the battery;

a voltage measurement unit for measuring a battery voltage at the constant current and a stop battery voltage;

an internal impedance measurement unit for measuring an internal impedance of the battery in accordance with the measured constant current value, battery voltage, and stop battery voltage; and

a determination unit for determining a life of the battery in accordance with the internal impedance measured by the internal impedance measurement unit.

2. The electrical apparatus according to claim 1, further comprising an output unit for presenting information about the determined life of the battery to a user.

3. The electrical apparatus according to claim 1, wherein the constant current flows when a predetermined time passes after starting charge of the battery.

4. A computer apparatus having a battery pack which repeatedly charges and discharges to supply power from the battery pack to a system body,

wherein the battery pack comprises:

a voltage measurement circuit for measuring a battery voltage;

a current measurement circuit for measuring a charge current; and

a CPU for computing an internal impedance in accordance with the measured battery voltage and charge current, and

wherein the system body comprises;

a controller for determining a life of the battery pack in accordance with the internal impedance computed by the CPU of the battery pack; and

a display for displaying a message about the determined life.

5. The computer apparatus according to claim 4, wherein the voltage measurement circuit of the battery pack measures the battery voltage when charge is performed and the battery voltage when the charge is stopped.

6. The computer apparatus according to claim 4, wherein the controller of the system body temporarily stops the charge of the battery pack when charging the battery pack at a constant current and determines the life of the battery pack in accordance with the internal impedance computed in accordance with the battery voltage when the charge is temporarily stopped.

7. A battery-life determination system for determining the life of a battery for performing charge and discharge and supplying power to a body, comprising:

an internal impedance measurement unit for measuring a voltage and current value of the battery at a constant current and a battery voltage when stopping supply of current and thereby determining the internal impedance of the battery; and

a determination unit for determining a life of the battery in accordance with the internal impedance determined by the internal impedance measurement unit.

8. The battery-life determination system according to claim 7, wherein the internal impedance measurement unit measures the internal impedance of the battery in accordance with the battery voltage and current value when charge is performed and the battery voltage when the charge is stopped.

9. The battery-life determination system according to claim 7, wherein the battery is configured as a battery pack to be set to the body and the internal impedance measurement unit is set to the battery pack.

10. The battery-life determination system according to claim 7, wherein the battery is configured as a battery pack to be set to the body and the internal-impedance measurement unit and the determination unit are provided on the body.

11. A battery-life determination system for determining the life of a secondary battery for supplying power to a body, the system comprising:

an under-charge-battery-voltage measurement unit for measuring the battery voltage while the secondary battery is charged;

a charge current measurement unit for measuring the charge current while the secondary battery is charged;

a stop unit for stopping charge of the secondary battery while the secondary battery is charged;

an under-stop-battery-voltage measurement unit for measuring the under-stop battery voltage of the secondary battery while charge of the secondary battery is stopped by the stop unit;

an internal impedance computation unit for computing the internal impedance of the secondary battery in accordance with the battery voltage and charge current under the charge and the under-stop battery voltage; and

a life determination unit for determining the life of a battery in accordance with the internal impedance computed by the internal impedance computation unit.

12. The battery-life determination system according to claim 11, wherein the stop unit stops charge under constant-current charge when the value of charge current to the secondary battery is stabilized.

14. The battery according to claim 13, further comprising a transmission unit for transmitting the information about the internal impedance computed by the computation unit to the body.

15. The battery according to claim 13, further comprising a charge stop unit for temporarily stopping charge under the constant-current charge.

17. The battery-life detection method according to claim 16, wherein the internal impedance is obtained by dividing the difference (Δ

V) between the battery voltage and the charge-stop battery voltage by the charge current value.

18. The battery-life detection method according to claim 16, wherein a complete battery life is divided into a plurality of stages and the determined battery life information is selected at a predetermined stage and a message containing information about such determined battery life is delivered to a user.

13. A battery for supplying power to a body by repeating charge and discharge, comprising:

an under-charge-voltage measurement unit for measuring the battery voltage under charge;

a current measurement unit for measuring the charge-current value under charge;

an under-stop-voltage measurement unit for measuring the battery voltage when charge is stopped; and

a computation unit for computing an internal impedance in accordance with the battery voltage measured by the under-charge-voltage measurement unit, the charge current value measured by the current measurement unit, and the battery voltage measured by the under-stop-voltage measurement unit.

16. A battery-life detection method for detecting a life of a battery for supplying power to a body by performing charge and discharge, comprising the steps of:

measuring a battery voltage while the battery is charged;

measuring a charge current value while the battery is charged;

measuring a charge-stop battery voltage when charge of the battery is stopped;

computing an internal impedance of a battery in accordance with the battery voltage, the charge current value, and the charge-stop battery voltage; and

determining the life of the battery in accordance with the internal impedance.

19. A battery-life detection method for detecting a life of a battery for performing charge and discharge and supplying power to a body, comprising the steps of:

measuring the voltage of the battery at a constant current whose value is stabilized while the battery is charged or discharged;

measuring the current value of the battery at the constant current;

stopping supply of current at the constant current;

measuring the stop battery voltage that is the voltage of the battery when supply of the current is stopped;

computing the internal impedance of a battery in accordance with the battery voltage, the current value, and the stop battery voltage; and

determining the life of a battery in accordance with the internal impedance.