Battery monitoring systems and methods are provided. The battery monitoring system may include a battery module and battery management circuitry. The battery module comprises battery cells and a gas sensor configured to detect the presence of gas within the battery module. The battery management circuitry is configured to receive a sensor signal from the gas sensor, determine whether the sensor signal indicates the presence of gas within the battery module, and in response to determining that the sensor signal indicates the presence of gas, take an action. The action may include increasing cooling to the battery cells, limiting a maximum load that can be applied to the battery module, disconnecting the battery module, or providing a warning. The battery module may also include a component that was doped with a chemical that begins to off-gas above an activation temperature. The gas sensor may be configured to detect the chemical.