BATTERY PACK AND ENERGY STORAGE SYSTEM

Embodiments of this application disclose a battery pack and an energy storage system, and relate to the field of power electronics technologies, to resolve a problem of how to implement overcurrent protection for a cell in a battery pack with a fast response speed, a simple circuit topology, and low costs. The battery pack includes a cell (110), where an emitter or a source of a first switching transistor (Q1) is connected to a positive electrode of the cell, and a first resistor (R1) and a second resistor (R2) are connected in series between a collector or a drain of the first switching transistor and a negative electrode of the cell; a third resistor (R3) is connected between the negative electrode of the cell and an emitter or a source of a second switching transistor (Q2), a collector or a drain of the second switching transistor is connected to an anode of a first Zener diode (ZD1), and a fourth resistor (R4) and a fifth resistor (R5) are connected in series between a cathode of the first Zener diode and the positive electrode of the cell; and a connection point between the first resistor and the second resistor is connected to a base or a gate of the second switching transistor, and a connection point between the fourth resistor and the fifth resistor is connected to a base or a gate of the first switching transistor.