Thermal Chain Determination Method and Thermal Chain Detection System for Battery Pack

A battery pack includes cells, a pressure contributing component contributing to a change in pressure in the battery pack, at least one pressure sensor configured to detect the pressure in the battery pack, and at least one voltage sensor configured to detect a voltage of the cells. A thermal chain determination method includes detecting the pressure in the battery pack, detecting the voltage of the cells, determining that the pressure in the battery pack is abnormal when an amount or rate of change is larger than a predetermined value, determining that the voltage of the cells is abnormal when an amount or rate of change in the detected voltage is larger than a predetermined value, or when an absolute value of the voltage of the cells is smaller than a predetermined value, and determining that a thermal chain occurs when both the pressure and the voltage are abnormal.