Fully-charged battery capacity detection method

• US 20080255783A1
• Filed: 04/08/2008
• Published: 10/16/2008
• Est. Priority Date: 04/10/2007
• Status: Active Grant

• Current Assignee: Panasonic Energy Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: TAMAI, Mikitaka
• Granted Patent: US 7,974,796 B2
• Time in Patent Office: Days
• US Class Current: 702/63
• CPC Class Codes: G01R 31/3828 using current integration

Abstract

In a fully-charged battery capacity detection method, first and second no-load voltages (VOCV1, VOCV2) of a battery are detected at first no-load timing and second no-load timing, respectively. First and second remaining capacities (SOC1 [%], SOC2 [%]) of the battery are determined based on the first and second no-load voltages, respectively, if the first no-load voltage (VOCV1) falls within a predetermined voltage range. A fully-charged capacity (Ahf) of the battery is calculated based on a remaining capacity variation rate (δS [%]) and a capacity variation value (δAh) of the battery. The variation rate of the remaining capacity is calculated based on the difference between the first and second remaining capacities. The capacity variation value of the battery is calculated based the integrated value of the charging current and discharge currents of the battery to be charged/discharged from the first no-load timing to the second no-load timing.

Claims

1. A fully-charged battery capacity detection method comprising:

a no-load voltage detection step that detects first and second no-load voltages (VOCV1, VOCV2) of a battery at first no-load timing and second no-load timing in that the battery is brought in a no-load state, respectively;

a remaining capacity determination step that determines whether the first no-load voltage (VOCV1) that is detected in the no-load voltage detection step falls within a predetermined voltage range, and determines first and second remaining capacities (SOC1 [%], SOC2 [%]) of the battery based on the first and second no-load voltages (VOCV1, VOCV2), respectively, if the first no-load voltage (VOCV1) falls within the predetermined voltage range;

a remaining capacity variation rate calculation step that calculates a remaining capacity variation rate (δ

S [%]) based on the difference between the first and second remaining capacities (SOC1 [%], SOC2 [%]) that are determined in the remaining capacity determination step;

a capacity variation detection step that calculates a capacity variation value (δ

Ah) of the battery based on the integrated value of charging and discharging currents of the battery to be charged/discharged from the first no-load timing to the second no-load timing; and

a fully-charged capacity calculation step that calculates a fully-charged capacity (Ahf) of the battery based on the remaining capacity variation rate (δ

S [%]) and the capacity variation value (δ

Ah) by the following formula

Ahf=δ

Ah/(δ

S/100)

2. The fully-charged battery capacity detection method according to claim 1, wherein it is determined whether the capacity variation value (δ

Ah) that is detected in the capacity variation detection step is larger than a predetermined value, and the fully-charged capacity (Ahf) of the battery is calculated based on the remaining capacity variation rate (δ

S [%]) and the capacity variation value (δ

Ah) in the fully-charged capacity calculation step if the capacity variation value (δ

Ah) is larger than the predetermined value.

3. The fully-charged battery capacity detection method according to claim 2, wherein the second no-load timing is timing in that the battery is brought in the no-load state after the capacity variation value (δ

Ah) becomes larger 10% of the rated capacity of the battery.

4. The fully-charged battery capacity detection method according to claim 1, wherein the second no-load timing is timing in that a predetermined period elapses after the first no-load timing.

5. The fully-charged battery capacity detection method according to claim 4, wherein the second no-load timing is timing in that a period of a few minutes to a few hours elapses after the first no-load timing.

6. The fully-charged battery capacity detection method according to claim 1, wherein the first no-load timing is timing in that the battery is brought in the no-load state before the battery is brought in charging operation, and the second no-load timing is timing in that the battery is brought in the no-load state after the end of the charging operation.

7. The fully-charged battery capacity detection method according to claim 5, wherein the second no-load timing is timing in that the battery is brought in the no-load state when a period of five minutes to one hour elapses after the end of battery charging operation.

8. The fully-charged battery capacity detection method according to claim 1, wherein the second no-load timing is timing before the battery is fully charged, wherein in the remaining capacity determination step it is determined whether the second no-load voltage (VOCV2) that is detected in the no-load voltage detection step falls within a predetermined voltage range, and the second remaining capacity (SOC2 [%]) of the battery is determined based on the second no-load voltage (VOCV2) if the second no-load voltage (VOCV2) falls within the predetermined voltage range.

9. The fully-charged battery capacity detection method according to claim 1, wherein the battery is a lithium-ion rechargeable battery.

10. The fully-charged battery capacity detection method according to claim 1, wherein the battery is a lithium-polymer battery.

11. The fully-charged battery capacity detection method according to claim 9, wherein the battery is a lithium-ion rechargeable battery that has a positive electrode that contains a three-compositional material.

12. The fully-charged battery capacity detection method according to claim 1, wherein the first remaining capacity (SOC1 [%]) of the battery is determined based on the first no-load voltage (VOCV1) by a stored function.

13. The fully-charged battery capacity detection method according to claim 1, wherein the first remaining capacity (SOC1 [%]) of the battery is determined based on the first no-load voltage (VOCV1) by a stored table.

14. The fully-charged battery capacity detection method according to claim 1, wherein the second remaining capacity (SOC2 [%]) of the battery is determined based on the second no-load voltage (VOCV2) by a stored function.

15. The fully-charged battery capacity detection method according to claim 1, wherein the second remaining capacity (SOC2 [%]) of the battery is determined based on the second no-load voltage (VOCV2) by a stored table.

16. The fully-charged battery capacity detection method according to claim 1, wherein the deterioration degree of the battery is determined based on the calculated fully-charged capacity (Ahf.

17. The fully-charged battery capacity detection method according to claim 1, wherein the calculated fully-charged capacity (Ahf) is sent to a mobile device.