HIGH VOLTAGE BATTERY THERMAL RUNAWAY MITIGATION SYSTEM

An electrified vehicle includes an electric traction motor, a high voltage (HV) battery system including a HV battery pack configured to power the electric traction motor. The HV battery pack includes a plurality of battery modules each configured to store electrical energy, an auxiliary storage device electrically coupled to the battery modules, and one or more switches/relays configured to selectively allow transfer of electrical charge from each battery module to the auxiliary storage device. A battery management system (BMS) includes a controller programmed to detect a thermal runaway event of one or more of the battery modules, and open/close the one or more switches/relays in response to detecting the thermal runaway event to thereby transfer electrical charge from the one or more battery modules experiencing the thermal runaway event to the auxiliary storage device, to thereby slow or prevent a propagation of the thermal runaway.