Battery charger with battery life judging function

• US 20070013344A1
• Filed: 07/11/2006
• Published: 01/18/2007
• Est. Priority Date: 07/12/2005
• Status: Active Grant

• Current Assignee: Hitachi KOKI Company Limited (Koki Holdings Co., Ltd.)
• Original Assignee: Hitachi KOKI Company Limited (Koki Holdings Co., Ltd.)
• Inventors: Funabashi, Kazuhiko, Takano, Nobuhiro, Aradachi, Takao
• Granted Patent: US 7,800,343 B2
• Time in Patent Office: Days
• US Class Current: 320/132
• CPC Class Codes: G01R 31/3646 for indicating electrical conditions or variables, e.g. visual or audible indicators
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health

Abstract

A charging device includes a battery voltage detecting circuit for detecting the voltage of a battery pack; and a microcomputer having RAM for temporarily storing a battery voltage detected by the battery voltage detecting circuit, and a CPU for calculating a battery voltage gradient from the battery voltage detected by the battery voltage detecting circuit and a battery voltage sampled a prescribed time earlier. The charging device determines that the life of the battery has expired when the voltage of the battery pack prior to charging is less than or equal to a prescribed value J and the battery voltage gradient within a prescribed time period after the start of charging is greater than or equal to a first prescribed value K. The charging device also includes a display circuit for notifying the user when the life of the battery pack has deteriorated.

Claims

1. A battery life judging device comprising:

a battery voltage detecting circuit that detects a battery voltage;

a memory that stores the battery voltage detected by the battery voltage detecting circuit;

a battery voltage gradient calculating unit that calculates a battery voltage gradient from the battery voltage detected by the battery voltage detecting circuit and a battery voltage detected a prescribed time earlier; and

a judging unit that judges that a life of a battery has expired when the battery voltage gradient within a prescribed time period after start of charging exceeds a first prescribed value.

2. The battery life judging device according to claim 1, wherein the judging unit determines that the life of a battery has nearly expired when the battery voltage gradient within the prescribed time period after the start of charging is less than the first prescribed value and greater than or equal to a second prescribed value, where the second prescribed value being less than the first prescribed value.

3. The battery life judging device according to claim 1, wherein the judging unit determines that the battery is healthy when the battery voltage gradient within the prescribed time period after the start of charging is less than the second prescribed value.

4. The battery life judging device according to claim 1, further comprising a display unit that notifies a user of judgment results for the battery.

5. The battery life judging device according to claim 4, wherein the display unit emits a first light when the battery is judged to be health, a second light when the life of the battery is judged to be nearly expired, and a third light when the life of the battery is judged to be expired, wherein the first light, the second light and the third light are different in color.

6. A battery life judging device comprising:

a battery voltage detecting circuit that detects a battery voltage;

a memory that stores the battery voltage detected by the battery voltage detecting circuit;

a battery voltage gradient calculating unit that calculates a battery voltage gradient from the battery voltage detected by the battery voltage detecting circuit and a battery voltage detected a prescribed time earlier; and

a judging unit that judges that a life of a battery has expired when the battery voltage before start of charging is less than or equal to a prescribed voltage and when the battery voltage gradient within a prescribed time period after the start of charging exceeds a first prescribed value.

7. The battery life judging device according to claim 6, wherein the judging unit determines that the life of a battery has nearly expired when the battery voltage gradient within the prescribed time period after the start of charging is less than the first prescribed value and greater than or equal to the second prescribed value, where a second prescribed value being less than the first prescribed value.

8. The battery life judging device according to claim 6, wherein the judging unit determines that the battery is healthy when the battery voltage gradient within the prescribed time period after the start of charging is less than the second prescribed value.

9. The battery life judging device according to claim 6, further comprising a display unit that notifies a user of judgment results for the battery.

10. The battery life judging device according to claim 9, wherein the display unit emits a first light when the battery is judged to be health, a second light when the life of the battery is judged to be nearly expired, and a third light when the life of the battery is judged to be expired, wherein the first light, the second light and the third light are different in color.

11. A battery charger comprising:

a battery voltage detecting circuit that detects a battery voltage;

a memory that stores the battery voltage detected by the battery voltage detecting circuit;

a microcomputer that implements a battery life judgment based on at least one of a battery voltage gradient within a prescribed time period after start of charging and a battery voltage before the start of charging, and provides judgment results depending on residual length of battery life; and

a display unit that indicates the judgment results while emitting lights of different color depending on the residual length of battery life.