Patent ID: 8030902

Claim:
A method for charging a battery module of a portable electronic apparatus in multiple stages, suitable for the battery module comprising a plurality of parallely-connected battery cell sets, the method comprising: x. charging the battery module via a trickle charging; y. determining whether or not the voltage of the battery module reaches a charging starting voltage; a. charging the battery module with a first predetermined current via constant current charging if the voltage of the battery module reaches the charging starting voltage; b. determining whether or not the voltage of any parallely-connected battery cell set in the battery module reaches a first predetermined voltage; c. charging the battery module with a second predetermined current via the constant current charging, wherein the second predetermined current equals to the first predetermined current minus a current difference value; d. determining whether or not the voltage of any parallely-connected battery cell set in the battery module reaches a second predetermined voltage; e. maintaining the battery module to be charged with the second predetermined voltage via constant voltage charging; f. determining whether or not the battery module is fulfilled; and g. maintaining the battery module to be charged with the second predetermined voltage via the constant voltage charging until the battery module is fulfilled.