In some other embodiments, other values may be assigned to the above-described status parameter and discharge protection parameter. In some embodiments, when the discharge electrical current is greater than a preset current threshold, the discharge protection parameter may be a constant. When the discharge electrical current is less than a preset current threshold, the discharge protection parameter may change according to the change of the battery temperature. When the battery temperature is less than a preset temperature, the discharge protection parameter may be a constant. When the battery temperature is greater than a preset temperature, the discharge protection parameter may change according to the change of the discharge electrical current of the battery. Further, the longest sustainable time duration may be inversely proportional to the discharge cut-off voltage.