Charging method for a battery assembly including a plurality of secondary batteries

DETAILED DESCRIPTION It is an object of the present invention to provide an improved method of charging a secondary battery assembly which avoids overcharging the normal secondary batteries if one of the batteries malfunctions.
These and other objects are achieved by a method of charging, in accordance with one embodiment of the present invention, which comprises the steps of: charging a secondary battery assembly including a plurality of secondary batteries; stopping charging when the secondary battery assembly is charged at a full charge level; resuming charging when the charge level of the secondary battery assembly falls below a predetermined charge level; monitoring the charging process after the resumption of charging; and modifying the charging if it is detected that the charging process after the resumption of charging is abnormal.
For example, in one embodiment, the charging apparatus detects an abnormal charge resumption process in the following manner.
The apparatus stops charging when the battery assembly is charged to a full charge level.
Upon resumption of charging, a timer measures the duration of time from the resumption of charging until charging is stopped again.
When the measured time period is less than a predetermined time period, the apparatus identifies this charge resumption as an abnormal one.
If so, the apparatus modifies the charging by, for example, stopping the charging until the battery assembly is taken off.