An example battery, a terminal, or a charging system can include a battery charging port, a battery discharging port, a battery negative port, an overcurrent protection element, a protection integrated circuit, a control switch, and an electrochemical cell. The battery charging port is connected to a positive electrode of the electrochemical cell, the control switch is connected in series between a negative electrode of the electrochemical cell and the battery negative port, the protection integrated circuit is connected in parallel to two ends of the electrochemical cell, and the protection integrated circuit is further connected to the control switch, so as to send a control signal to the control switch. In addition, the overcurrent protection element is connected in series between the battery discharging port and the positive electrode of the electrochemical cell.