Rechargeable battery charging method and apparatus

• US 7,339,354 B2
• Filed: 02/17/2005
• Issued: 03/04/2008
• Est. Priority Date: 03/04/2004
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Sanpei, Akira
• Primary Examiner(s): Vu; Bao Q.
• Assistant Examiner(s): Zhang; Jue
• Application Number:
  US11/059,368
• Publication Number:
  US 20050194938A1
• Time in Patent Office: 1,111 Days
• Field of Search: 320141-146, 320/139, 320/140, 320/129, 323/265, 323/266, 323/273, 323/275
• US Class Current: 320/141
• CPC Class Codes: H02J 7/0071 with a programmable schedule
• CPC Class Codes: H02J 7/00711 with introduction of pulses during the charging process
• CPC Class Codes: H02J 7/007182 in response to battery voltage

Abstract

A method and an apparatus for charging a lithium-ion based rechargeable battery in a short time is provided. A terminal voltage of the rechargeable battery is compared with a predetermined first set voltage V1 while charging the rechargeable battery with a constant current; pulse charging is performed in which charging is halted after the rechargeable battery is charged with the constant current only during a predetermined first set time T1 when the terminal voltage becomes the first set voltage V1 or more; both an elapsed time An from the start of the halt and a terminal voltage Bn at the elapsed time An are measured a plurality of times during the halt of charging in the pulse charging and the terminal voltage Bn is compared with a predetermined second set voltage V2; whether or not the terminal voltage drops to the second set voltage V2 or less is presumed based on measurement results of the elapsed time An and the terminal voltage Bn in the case where the terminal voltage Bn is higher than the second set voltage V2 when the elapsed time An reaches a predetermined second set time T2; both the pulse charging and the presumption of the terminal voltage are repeated when presumed that the terminal voltage drops to the second set voltage V2 or less; and charging is ended when presumed that the terminal voltage does not drop to the second set voltage V2 or less.

Claims

1. A rechargeable-battery charging method comprising the steps of:

performing pulse charging in which a terminal voltage of a rechargeable battery is compared with a predetermined first set voltage while charging said rechargeable-battery with a constant current and charging is halted after a predetermined first set time elapses when said terminal voltage becomes said predetermined first set voltage or more;

measuring an elapsed time An from when the charging is halted and measuring said terminal voltage Bn while the charging is halted;

charging said rechargeable-battery for the predetermined first set time where it is determined that said terminal voltage Bn drops to said predetermined second set voltage or less within predetermined second set time;

repeating said measuring and charging steps until said terminal voltage Bn does not drop to said predetermined second set voltage or less within said predetermined second set time and determining a number of times n that said rechargeable-battery is charged for the predetermined first set time during a charging cycle;

determining a calculated value of said terminal voltage Bn corresponding to a predetermined third set time that is longer than said predetermined second set time, wherein the calculated value accounts for the number of times n that said rechargeable-battery is charged; and

repeating said charging where the calculated value of said terminal voltage Bn is said predetermined second set voltage or less and ending said charging where the calculated value of said terminal voltage Bn does not drop to said second set voltage or less.

2. The rechargeable-battery charging method according to claim 1, wherein during the halt of charging in said pulse charging, said terminal voltage Bn at the time when said elapsed time An from the start of the halt becomes the predetermined third set time a calculation based on a data group (An, Bn) including said elapsed time An and said terminal voltage Bn, and in the case where a calculated value of said terminal voltage Bn is said second set voltage or less, both said pulse charging and the calculation of said terminal voltage Bn are repeated, and in the case where a calculated value of said terminal voltage Bn is higher than said second set voltage, charging is ended, and wherein the calculation based on the data group (An, Bn) comprises:

Data group (Cn, Bn) is made from the data group (An, Bn), where

Cn=1/√

{square root over (An)}, where

D and E are obtained from the data group (Cn, Bn) by the least-square method, where

3. The rechargeable-battery charging method according to claim 2, wherein

the predetermined third set time is infinite time.

4. The rechargeable-battery charging method according to claim 2 or 3, wherein

both said pulse charging and determining the calculated value of said terminal voltage Bn are repeated until the calculated value of said terminal voltage Bn becomes continuously higher than said predetermined or N consecutive instances of said pulse charging and determining the calculated value, wherein N is an integer of 2 or more.

5. The rechargeable-battery charging method according to claim 1, wherein

each terminal voltage of a plurality of rechargeable batteries is measured when charging a battery pack in which said plurality of rechargeable batteries are connected, and the highest terminal voltage thereof is compared with said first set voltage and said second set voltage.

6. A rechargeable-battery charging apparatus comprising:

a charger for charging a rechargeable battery;

a voltage detector for detecting a terminal voltage of said rechargeable battery; and

a controller for controlling charging of said rechargeable battery, wherein

said controller performs

processing of comparing the terminal voltage of said rechargeable battery with a predetermined first set voltage using a detection result of said voltage detector while said rechargeable battery is charged with a constant current by said charger,

processing of pulse charging said rechargeable-battery wherein charging is halted after a predetermined first set time elapses when said terminal voltage becomes said predetermined first set voltage or more,

processing of measuring an elapsed time An from when the charging is halted and measuring said terminal voltage Bn while the charging is halted, charging said rechargeable-battery for the predetermined first set time where it is determined that said terminal voltage Bn drops to said predetermined second set voltage or less within predetermined second set time, repeating said measuring and charging steps until said terminal voltage Bn does not drop to said predetermined second set voltage or less within said predetermined second set time and determining a number of times n that said rechargeable-battery is charged for the predetermined first set time during a charging cycle, determining a calculated value of said terminal voltage Bn corresponding to a predetermined third set time that is longer than said predetermined second set time, wherein the calculated value accounts for the number of times n that said rechargeable-battery is charged, and

processing of repeating said charging where the calculated value of said terminal voltage Bn is said predetermined second set voltage or less and ending said charging where the calculated value of said terminal voltage Bn does not drop to said second set voltage or less.