A method for predicting remaining capacity of a battery includes: (a) determining an initial battery capacity; (b) measuring a second voltage; (c) calculating a maximum possible battery voltage and a minimum possible battery voltage according to the second voltage, a maximum possible battery current and a minimum possible battery current, and an internal resistance; (d) calculating a maximum possible battery remaining capacity and a minimum possible battery remaining capacity according to the maximum possible battery voltage, the minimum possible battery voltage, and the voltage-remaining capacity table; (e) comparing the maximum possible battery current with the minimum possible battery current; and (f) calculating a remaining capacity of the battery according to a comparison result in step (e), the maximum possible battery remaining capacity, and the minimum possible battery remaining capacity.