Method of computing remaining battery capacity and battery pack

• US 20030117143A1
• Filed: 12/20/2002
• Published: 06/26/2003
• Est. Priority Date: 12/26/2001
• Status: Active Grant

• Current Assignee: Godo Kaisha IP Bridge 1 (IP Bridge, Inc.)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Okada, Tetsuya
• Granted Patent: US 6,756,768 B2
• Time in Patent Office: Days
• US Class Current: 324/428
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/3828 using current integration
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables

Abstract

The method of computing remaining battery capacity computes battery discharge capacity from the integrated value of the product of discharge current and voltage to find remaining battery capacity via energy (integrated power). Battery discharge capacity is computed by adding the integrated value of power consumed by internal resistance to a discharge capacity value calculated from the integrated product of discharge current and voltage, and remaining battery capacity is computed from this battery discharge capacity.

Claims

1. A method of computing remaining battery capacity by computing battery discharge capacity from the integrated value of the product of discharge current and voltage and computing remaining battery capacity via energy (integrated power) comprising the steps of:

a step to measure internal battery resistance; and

a step to compute battery discharge capacity by adding the integrated value of power consumed by the internal resistance to a computed discharge capacity value calculated from the integrated product of discharge current and voltage, and to compute remaining battery capacity from this battery discharge capacity.

2. A method of computing remaining battery capacity as recited in claim 1 wherein the integrated value of power consumed by the internal resistance is subtracted from a computed charge capacity value calculated from the integrated product of battery charging current and voltage to compute battery charge capacity and remaining battery capacity.

3. A method of computing remaining battery capacity as recited in claim 1 wherein internal resistance is computed by measuring open circuit battery voltage, and charging voltage and current during battery charging.

4. A method of computing remaining battery capacity as recited in claim 1 wherein internal resistance is computed by measuring open circuit battery voltage, and discharge voltage and current during battery discharge.

5. A method of computing remaining battery capacity as recited in claim 1 wherein the computed discharge capacity value is calculated from the integrated product of discharge current, discharge voltage, and discharge efficiency.

6. A method of computing remaining battery capacity as recited in claim 2 wherein the computed charge capacity value is calculated from the integrated product of charging current, charging voltage, and charging efficiency.

7. A method of computing remaining battery capacity as recited in claim 1 wherein battery time of use and temperature are measured during battery operation, and the internal resistance value is corrected according to this time, temperature and a pre-stored degradation coefficient.

8. A battery pack comprising:

a computation circuit to compute battery discharge capacity from the

integrated value of the product of discharge current and voltage, and

compute remaining battery capacity via energy (integrated power);

wherein the computation circuit measures internal battery resistance, computes battery discharge capacity by adding the integrated value of power consumed by the internal resistance to a computed discharge capacity value calculated from the integrated product of discharge current and voltage, and computes remaining battery capacity from this battery discharge capacity.

9. A battery pack as recited in claim 8 wherein the computation circuit subtracts the integrated value of power consumed by the internal resistance from a computed charge capacity value calculated from the integrated product of battery charging current and voltage to compute battery charge capacity and remaining battery capacity.

10. A battery pack as recited in claim 8 wherein the computation circuit computes internal resistance by measuring open circuit battery voltage, and charging voltage and current during battery charging.

11. A battery pack as recited in claim 8 wherein the computation circuit computes internal resistance by measuring open circuit battery voltage, and discharge voltage and current during battery discharge.

12. A battery pack as recited in claim 8 wherein the computation circuit calculates the computed discharge capacity value from the integrated product of discharge current, discharge voltage, and discharge efficiency.

13. A battery pack as recited in claim 9 wherein the computation circuit calculates the computed charge capacity value from the integrated product of charging current, charging voltage, and charging efficiency.