Method for detecting full charge state of battery

A device for detecting a full charge state of a battery during a charging operation, comprising:

• a measuring circuit for measuring a battery voltage;
• and
• a controller for controlling said measuring circuit;
• wherein said controller obtains a first data series including first to N-th data items, where N is a predetermined positive integer not less than 2, the first to N-th data items of the first data series corresponding to battery voltages measured by said measuring circuit at first sampling intervals during a first sampling time period, respectively;
• said controller obtains a second data series including first to N-th data items, the first to N-th data items of the second data series corresponding to battery voltages measured by said measuring circuit at second sampling intervals during a second sampling time period, respectively, a predetermined time delay being provided between a beginning of the first sampling time period and a beginning of the second sampling time period, the second sampling intervals being the same as the first sampling intervals;
• and
• said controller compares an i-th data item of the first data series and an i-th data item of the second data series to obtain a number of times that the i-th data item of the second data series is smaller than the i-th data item of the first data series, where i=1, 2, . . . , N, and judges whether or not the battery has reached the full charge state on the basis of a ratio of the number of times to N.

A cellular telephone comprising:

• a measuring circuit for measuring a battery voltage of a battery;
• and
• a controller for controlling said measuring circuit and a charging circuit of a charger for the cellular telephone;
• wherein said controller obtains a first data series including first to N-th data items, where N is a predetermined positive integer not less than 2, the first to N-th data items of the first data series corresponding to battery voltages measured by said measuring circuit at first sampling intervals during a first sampling time period, respectively;
• said controller obtains a second data series including first to N-th data items, the first to N-th data items of the second data series corresponding to battery voltages measured by said measuring circuit at second sampling intervals during a second sampling time period, respectively, a predetermined time delay being provided between a beginning of the first sampling time period and a beginning of the second sampling time period, the second sampling intervals being the same as the first sampling intervals;
• said controller compares an i-th data item of the first data series and an i-th data item of the second data series to obtain a number of times that the i-th data item of the second data series is smaller than the i-th data item of the first data series, where i=1, 2, . . . , N, and judges whether or not the battery has reached the full charge state on the basis of a ratio of the number of times to N;
• and
• said controller causes the charging circuit of the charger to stop charging when said controller judges that the battery has reached the full charge state.