CHARGER

• US 20130063079A1
• Filed: 09/07/2012
• Published: 03/14/2013
• Est. Priority Date: 09/12/2011
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: KAWAI, Akira, IKEDA, Masaki, SAKAUE, Masaaki, OHASHI, Toshiharu
• Granted Patent: US 9,178,380 B2
• Time in Patent Office: Days
• US Class Current: 320/107
• CPC Class Codes: H02J 7/0049 Detection of fully charged condition
• CPC Class Codes: H02J 7/00714 in response to battery charging or discharging current
• CPC Class Codes: H02J 7/007182 in response to battery voltage
• CPC Class Codes: H02J 7/04 Regulation of charging current or voltage

Abstract

A charger includes an output circuit unit to output a charging current to a secondary battery, a voltage detection unit to detect a voltage of the secondary battery, and a control unit to control the output circuit unit, whereby constant current charging and constant voltage charging are performed. The control unit decreases a constant current value of the charging current by stages during the constant current charging and determines that the secondary battery has deteriorated by using a first voltage drop value of the secondary battery occurring upon first conversion and a second voltage drop value of the secondary battery occurring upon second conversion.

Claims

1. A charger, comprising an output circuit unit configured to output a charging current to a secondary battery, a voltage detection unit configured to detect a voltage of the secondary battery, and a control unit configured to control the output circuit unit, whereby constant current charging, in which the charging current is flows at a constant current, and constant voltage charging, in which the charging current flows at a constant voltage after the constant current charging, are performed,

wherein the control unit decreases a constant current value of the charging current by stages during the constant current charging and determines whether or not the secondary battery has deteriorated by using a first voltage drop value of the secondary battery that occurs upon first conversion in which the constant current value is converted and a second voltage drop value of the secondary battery that occurs upon second conversion in which a constant current value which is different from that of the first conversion is converted.

2. The charger of claim 1, wherein a memory device is provided in a battery pack including the secondary battery, and the control unit:

stores a number of charging times of the secondary battery and the first and the second voltage drop values of the secondary battery corresponding to the number of charging times in the memory device;

compares the first and the second voltage drop values in an initial phase in which the number of charging times of the secondary battery is equal to or smaller than a predetermined value with the first and the second voltage drop values in a phase in which the number of charging times of the secondary battery is greater than that in the initial phase; and

excludes a deviation in first and second voltage drop values of secondary batteries of respective battery packs in the initial phase.

3. The charger of claim 1, further comprising a notification unit configured to provide a result of the determination to an outside.

4. The charger of claim 2, further comprising a notification unit configured to provide a result of the determination to an outside.

5. The charger of claim 1, wherein the control unit determines that the secondary battery has deteriorated by using a ratio between the first voltage drop value and the second voltage drop value.

6. The charger of claim 2, wherein the control unit determines that the secondary battery has deteriorated by using a ratio between the first voltage drop value and the second voltage drop value.

7. The charger of claim 1, wherein the control unit determines that the secondary battery has deteriorated by using an average of the first voltage drop value and the second voltage drop value.

8. The charger of claim 2, wherein the control unit determines that the secondary battery has deteriorated by using an average of the first voltage drop value and the second voltage drop value.

9. A charger, comprising an output circuit unit configured to output a charging current to a secondary battery, a voltage detection unit configured to detect a voltage of the secondary battery, and a control unit configured to control the output circuit unit, whereby constant current charging, in which the charging current is flows at a constant current, and constant voltage charging, in which the charging current flows at a constant voltage after the constant current charging, are performed,

wherein the control unit decreases a constant current value of the charging current by stages during the constant current charging and determines whether or not the secondary battery has deteriorated if a voltage drop value of the secondary battery, which is detected by the voltage detection unit when the constant current value is converted, is equal to or greater than a predetermined value, and

wherein a memory device is provided in a battery pack including the secondary battery, and the control unit:

stores a number of charging times of the secondary battery and the voltage drop value of the secondary battery corresponding to the number of charging times in the memory device;

compares the voltage drop value in an initial phase in which the number of charging times of the secondary battery is equal to or smaller than a predetermined value with the voltage drop value in a phase in which the number of charging times of the secondary battery is greater than that in the initial phase; and

excludes a deviation in voltage drop values of secondary batteries of battery packs in the initial phase.

10. The charger of claim 9, further comprising a notification unit configured to provide a result of the determination to an outside.