In some embodiments, the processor 51 is further configured to obtain the continuous discharge time duration for the battery being discharged at the discharge cut-off voltage, and to accumulate the continuous discharge time duration of different discharge cut-off voltages within the discharge cycle of the battery, and to determine whether to perform a discharge protection operation according to the accumulated continuous discharge time duration. In some embodiments, the approach to accumulate the continuous discharge time duration of different discharge cut-off voltages may include that the processor 51 modifies the continuous discharge time duration corresponding to each of different discharge cut-off voltages by using a modification factor corresponding to the discharge cut-off voltage, where different discharge cut-off voltages correspond to different modification factors; and accumulates the modified continuous discharge time durations.