Battery charging method

• US 20050017692A1
• Filed: 07/22/2004
• Published: 01/27/2005
• Est. Priority Date: 07/25/2003
• Status: Active Grant

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Izumi, Yoshikazu, Yamashita, Takahiro, Kuroda, Yasushi, Furukawa, Akio
• Granted Patent: US 7,180,269 B2
• Time in Patent Office: Days
• US Class Current: 320/150
• CPC Class Codes: H02J 7/0071 with a programmable schedule
• CPC Class Codes: H02J 7/007194 of the battery

Abstract

The battery charging method detects battery temperature and comprises a temperature maintaining charging step wherein average charging current is controlled to drive battery temperature to a holding temperature, and charging is performed while maintaining battery temperature at that holding temperature. In addition, a temperature increasing charging step is provided prior to the temperature maintaining charging step. The battery is charged with a current which raises battery temperature until the holding temperature is reached. When battery temperature rises to the holding temperature in the temperature increasing charging step, charging can transition to the temperature maintaining charging step.

Claims

1. A battery charging method comprising a temperature maintaining charging step which detects battery temperature, controls average charging current to make the battery temperature become equal to a holding temperature, and charges the battery while maintaining battery temperature at the holding temperature.

2. A battery charging method as recited in claim 1 wherein the holding temperature is 50°

C. to 65°

C.

3. A battery charging method as recited in claim 1 wherein a temperature increasing charging step is provided prior to the temperature maintaining charging step, the battery is charged with a current that causes battery temperature to rise until reaching the holding temperature, when battery temperature reaches the holding temperature by charging in the temperature increasing charging step, charging transitions to the temperature maintaining charging step.

4. A battery charging method as recited in claim 3 wherein charging current in the temperature increasing charging step provides charging of 1.5C to 10C.

5. A battery charging method as recited in claim 3 wherein charging current in the temperature increasing charging step provides charging of 2C to 8C.

6. A battery charging method as recited in claim 3 wherein charging current in the temperature increasing charging step provides charging of 2C to 5C.

7. A battery charging method as recited in claim 3 wherein charging current in the temperature increasing charging step results in a rate of battery temperature rise of 1°

C./minute to 5C/minute

8. A battery charging method as recited in claim 3 wherein the battery is charged with a continuous flow of current in the temperature increasing charging step, the battery is pulse charged in the temperature maintaining charging step, average charging current is controlled by changing the pulse charging duty factor according to battery temperature, when battery temperature increases, the duty factor for pulse charging the battery is reduced, when battery temperature decreases, the duty factor for pulse charging the battery is increased, and average charging current is controlled to charge while maintaining battery temperature at the holding temperature.

9. A battery charging method as recited in claim 3 wherein if the rate of battery temperature rise during the temperature increasing charging step is equal to or exceeds a specified rate, charging is suspended.

10. A battery charging method as recited in claim 3 wherein battery temperature is detected at the start of charging, when battery temperature is within a specified temperature range for commencing charging, the temperature increasing charging step is started, when battery temperature is either below or above the specified temperature range for commencing charging, ordinary charging is performed while monitoring battery voltage.

11. A battery charging method as recited in claim 10 wherein the specified temperature range for commencing charging is 0°

C. to 40°

C.

12. A battery charging method as recited in claim 10 wherein the specified temperature range for commencing charging is 10C to 30°

C.

13. A battery charging method as recited in claim 10 wherein charging current is limited during ordinary charging to provide charging of 1C or below.

14. A battery charging method as recited in claim 3 wherein battery internal resistance is detected at the start of charging, if internal resistance is greater than a specified resistance, ordinary charging is performed while monitoring battery voltage, if internal resistance becomes less than the specified resistance after ordinary charging, the temperature increasing charging step is started.

15. A battery charging method as recited in claim 14 wherein charging current is limited during ordinary charging to provide charging of 1C or below.