Method for controlling battery pack

Abstract

A method controls a battery pack that includes a rechargeable battery, a control circuit that controls charge operation of the battery, and a charge control element that controls the charge current through the control circuit. In the method, even though the control circuit controls the charge control element so that the charge control element turns to OFF, in a case where the charge current is detected, the control circuit determines that abnormality occurs if detecting that the current flows at a rate not less than a first current value during a first detection period, and additionally determines that abnormality occurs if detecting a state the current flows at a rate less than the first current value for a second detection period longer than the first detection period.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit block diagram of a battery pack according to one embodiment of the present invention;

FIG. 2 is a flow chart of one embodiment of the present invention;

FIG. 3 is a detailed flow chart showing step S10 in FIG. 2 of the present invention; and FIG. 4 is a detailed flow chart showing step S20 in FIG. 2 of the present invention;

Claims

1. A method for controlling charge current of a battery pack that includes a rechargeable battery, a control circuit that controls charge operation of the battery, and a charge control element that is controlled by the control circuit so as to control the charge current, the method comprising the steps of: detecting the charge current of the rechargeable battery in the charge operation and measuring detection time by means of the control circuit, the control circuit controlling the charge control element to ON in the charge operation; andcontrolling the charge control element by means of the control circuit so that the charge control element turns to OFF if the control circuit determines that abnormality occurs based on the charge current and the detection time, whereinin a state where the control circuit controls the charge control element to OFF, the control circuit determines that abnormality occurs if detecting a state where the charge current flows at a rate not less than a first current value during a first detection period, and additionally determines that abnormality occurs if detecting a state where the charge current flows at a rate less than the first current value for a second detection period longer than the first detection period.

2. The method according to claim 1, wherein in the state where the control circuit controls the charge control element so that the charge control element turns to OFF, the control circuit repeats the detection whether the charge current flows at a rate not less than the first current value during the first detection period, and the detection whether the charge current flows at a rate less than the first current value during the second detection period longer than the first detection period at a constant cycle period, and thus determines abnormality.

3. The method according to claim 1, wherein the first detection current is 100 mA, and the first detection period is 20 sec.

4. The method according to claim 1, wherein the second detection current is 20 mA, and the second detection period is 90 sec.

5. The method according to claim 1, wherein the second detection current is not less than 1 mA.

6. The method according to claim 1, wherein the rechargeable battery is a nickel-hydrogen battery.

7. The method according to claim 1, wherein the rechargeable battery is a lithium-ion rechargeable battery.

8. The method according to claim 1, wherein the battery pack includes three or four cells of lithium-ion rechargeable batteries that are connected in serial.

9. The method according to claim 1, wherein a switching transistor is used as the charge control element.

10. The method according to claim 1, wherein the control circuit provides an OFF signal to the charge control element and thus controls the charge control element so that the charge control element turns to OFF.

11. The method according to claim 1, wherein the control circuit controls the charge control element so that the charge control element turns to OFF if detecting at least one of full-charge, abnormal current, abnormal temperature and abnormal voltage.

12. The method according to claim 11, wherein the rechargeable battery is a nickel-hydrogen battery, and the control circuit controls the charge control element so that the charge control element turns to OFF if detecting voltage drop −ΔV relative to the peak voltage of battery voltage and thus determining that the battery is in the full-charge state.

13. The method according to claim 11, wherein the rechargeable battery is a lithium-ion rechargeable battery, and the control circuit controls the charge control element so that the charge control element turns to OFF if detecting that battery voltage is not less than a preset value and the charge current is not more than a preset value and thus determining that the battery is in the full-charge state.

14. The method according to claim 1, wherein the control circuit communicates with a device in which the battery pack is set through a communication processing portion if detecting abnormality of the battery.

15. The method according to claim 1, wherein a fuse that is connected to the battery in serial is disconnected if it is determined that abnormality occurs.