THERMAL RUNAWAY PREVENTION

A battery assembly can include a pair of batteries. The battery pair may be electrically coupled by a bimetallic strip. When the temperature of the battery assembly exceeds a threshold temperature, the bimetallic strip deforms so that the coupling between the first and second batteries breaks. In other cases, the battery pair may be coupled by a spring-loaded connector. A sacrificial block configured to melt if the temperature of the battery assembly increases beyond the threshold temperature may force the spring into an energy-storing configuration. When the sacrificial block melts, the spring is released, and the connector is forced in a direction away from the battery terminals. Finally, the battery assembly may include a thermopile and one or more relays. When a temperature gradient of the thermopile exceeds a threshold gradient, the thermopile generates a voltage that causes the relays to disconnect the battery assembly from a charging circuit.