Charge control device for a secondary battery

• US 7,619,389 B2
• Filed: 11/10/2005
• Issued: 11/17/2009
• Est. Priority Date: 04/22/2005
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Wanibuchi, Tohru
• Primary Examiner(s): Tso; Edward
• Assistant Examiner(s): WILLIAMS, ARUN C
• Application Number:
  US11/270,468
• Publication Number:
  US 20060238166A1
• Time in Patent Office: 1,468 Days
• Field of Search: 320/118, 320/129, 320/132, 320/136, 320/137, 320/149, 320/150, 320/163, 320152-155, 320157-159, 320/112, 320/114, 320/128, 324431-433
• US Class Current: 320/128
• CPC Class Codes: H02J 7/0069 Charging or discharging for charge maintenance, battery initiation or rejuvenation

Abstract

A charge circuit 6 supplies a charging voltage (Vc) or a charging current to a secondary battery 2, 24 to 26 used for driving an appliance 21; a charged level setting device 5, Sc1 causes the charge circuit 6 to charge the secondary battery 2, 24 to 26 to a predetermined charged level, and detection means 12 detects a charged level of the secondary battery 2; a discharge section 21, 5, Sc1 discharges the secondary battery 2; and control means operates the charge circuit 6 when the predetermined charged level is higher than the detected charged level, and discharges the secondary battery by the discharge section 21, 5, Sc1 when the predetermined charged level is lower than the detected charged level Thus, it is possible to provide a charge control device capable of extending a cycle life of a secondary battery.

Claims

1. A charge control device comprising:

a charge circuit for supplying a charging voltage (Vc) or a charging current (Ic) to a secondary battery used for driving an appliance;

charged level setting means for switching a charged mode between a fully charged mode in which a fully charged state is a targeted charged state and a low charged mode in which a charged state whose charging rate is decreased by a predetermined percentage from that of the fully charged state is a targeted charged state;

detection means for detecting a charged level of the secondary battery;

discharge means for discharging the secondary battery;

control means for operating the charge circuit while a charged level detected by the detection means is lower than a targeted charged state in the charged mode, which is currently selected by the charged level setting means, and operating the discharge means while a charged level detected by the detection means is higher than a targeted charged state in the charged mode, which is currently selected by the charged level setting means; and

a storage device for storing a fully charged capacity of the secondary battery in the fully charged mode, and for storing a fully charged capacity of the secondary battery in the low charged mode,

wherein in the low charged mode, a remaining capacity of the secondary battery is indicated in accordance with the following equation;

RSOC(%)=RC/(FCC/CV)*100,

wherein RSOC is the remaining capacity of the secondary battery, RC is a current charge capacity of the secondary battery, FCC is the fully charged capacity of the secondary battery in the low charged mode, and CV is a conversion factor, and

wherein the fully charged mode is a first constant-voltage charged mode in which the secondary battery is charged at a first voltage, and the low charged mode is a second constant-voltage charged mode in which the secondary battery is charged at a second voltage which is lower than the first voltage.

2. The charge control device according to claim 1, further comprising notification means for notifying a user of the remaining capacity of the secondary battery.

3. The charge control device according to claim 1, further comprising:

temperature detection means for detecting a temperature of the secondary battery;

calculation means for calculating a usage period of the appliance; and

display means for prompting a user to change the charged level, either when the detected charged level is higher than a predetermined charged level and the detected temperature is higher than a predetermined temperature, or when the calculated usage period is longer than a predetermined period.

4. The charge control device according to claim 1, wherein the discharge means discharges the secondary battery through an operation of the appliance by disconnecting an external power supply to the appliance.

5. The charge control device according to claim 4, further comprising power source control means for controlling a power source of the appliance,

wherein when the appliance is not in operation and a predetermined charged level is lower than the detected charged level, the power source control means automatically turns on the power source of the appliance to discharge the secondary battery, and when the discharge is completed, the power source control means automatically stops the operation of the appliance.

6. The charge control device according to claim 1, wherein the charged level setting means sets a charging voltage which is higher by a predetermined value (α

) than a minimum voltage (Vcmin) at which the secondary battery can be charged, and causes the secondary battery to be charged to a predetermined charged level.

7. The charge control device according to claim 6, wherein the charged level setting means causes a charge of the secondary battery to stop when the secondary battery is charged to the predetermined charged level, and causes the secondary battery to drive the appliance.

8. The charge control device according to claim 7, wherein the charged level setting means causes the charge of the secondary battery to resume immediately before the secondary battery is completely discharged.

9. The charge control device according to claim 1, wherein the predetermined percentage is greater than 0% and less than 100%.

10. The charge control device according to claim 1, wherein the charged level setting means is controlled by a user.

11. The charge control device according to claim 1, wherein the first voltage is 4.2 volts and the second voltage is 4.0 volts.

12. The charge control device according to claim 11, wherein the conversion factor is 0.8.

13. The charge control device according to claim 1, wherein said storage device is an EEPROM.