Battery charger having a plurallty of channels

• US 20020167295A1
• Filed: 03/28/2002
• Published: 11/14/2002
• Est. Priority Date: 03/29/2001
• Status: Active Grant

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Yamashita, Takahiro
• Granted Patent: US 6,771,050 B2
• Time in Patent Office: Days
• US Class Current: 320/150
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: H02J 7/007194 of the battery

Abstract

A battery charger is for the purpose of charging a plurality of rechargeable batteries and is provided with temperature sensors for detecting battery temperature. The battery charger compares the battery temperature detected by the temperature sensors and charging stop temperature, and stops charging when the detected temperature becomes greater than the charging stop temperature. The battery charger has a plurality of attachment detecting portions for detecting attachment of the batteries respectively and independently. The number of temperature sensors is less than the total number of the batteries to be attached. The battery charger varies the charging stop temperature for stopping charging in accordance with battery attachment positions detected by each attachment detecting portion.

Claims

1. A battery charger having a plurality of channels for charging a plurality of rechargeable batteries attached in a detachable fashion comprising:

(a) temperature sensors for detecting temperature of batteries to be charged, the number of which is less than the total number of the batteries to be attached;

(b) a plurality of attachment detectors for respectively and independently detecting the presence of the batteries; and

(c) a control circuit comparing the temperature detected by the temperature sensors and charging stop temperature and stopping charging when the detected temperature becomes greater than the charging stop temperature, and varies the charging stop temperature for stopping charging in accordance with battery attachment positions detected by each attachment detector.

2. A battery charger having a plurality of channels as recited in claim 1 wherein charging current is cut off to stop charging when the detected temperature becomes the charging stop temperature.

3. A battery charger having a plurality of channels as recited in claim 1 wherein charging is virtually stopped by switching charging current to trickle charging current when the detected temperature becomes the charging stop temperature.

4. A battery charger having a plurality of channels as recited In claim 1 wherein the control circuit comprising:

(a) switching devices connected to the batteries; and

(b) a charging/discharging control circuit for controlling the switching devices.

5. A battery charger having a plurality of channels as recited in claim 1 wherein the control circuit varies the charging stop temperature in accordance with the temperature at the beginning of charging.

6. A battery charger having a plurality of channels as recited in claim 1 wherein the control circuit makes the charging stop temperature high when a multiplicity of batteries are attached and low when the number of batteries is decreased.

7. A battery charger having a plurality of channels as recited In claim 4 wherein the control circuit switches off all the switching devices to stop charging when one of the temperature sensors detects the temperature that is greater than the charging stop temperature.

8. A battery charger having a plurality of channels as recited in claim 4 wherein when one of the temperature sensors detects the temperature that is greater than the charging stop temperature, only the switching devices disposed near the temperature sensor that has detected the temperature exceeding the charging stop temperature are switched off, instead of all the switching devices.

9. A battery charger having a plurality of channels as recited in claim 1 wherein the temperature sensor is disposed between two adjacent batteries.

10. A battery charger having a plurality of channels as recited in claim 9 wherein the battery charger forms a projecting convex part between the adjacent batteries, and the temperature sensor is placed on the projecting convex part.

11. A battery charger having a plurality of channels as recited in claim 1 wherein the temperature sensor is disposed almost in the middle of the batteries that are arranged In three or more parallel rows.

12. A battery charger having a plurality of channels as recited in claim 1 wherein a temperature sensor is disposed in the middle of the batteries arranged in three rows.

13. A battery charger having a plurality of channels as recited in claim 1 wherein a temperature sensor is disposed in the middle of the batteries arranged in four rows.

14. A battery charger having a plurality of channels as recited in claim 1 wherein the attachment detectors detect the presence of the batteries by detecting voltage change at the output terminals connected to the batteries.

15. A battery charger having a plurality of channels as recited in claim 1 wherein the attachment detectors are limit switches detecting the presence of the batteries.