Development of sensor and optimal placement for smoke detection in an electric vehicle battery pack

There is currently a trend in the automotive industry to replace combustion engines with electric motors or a combination of an electric motor and a combustion engine, thereby substantially reducing the environmental impact of automobiles by reducing or completely eliminating car emissions. In this paper various strategies for positioning of smoke sensor within the battery pack assembly for smoke detection are deliberated. Proper placement of the smoke sensor results in two important design objectives: to detect smoke as soon as the fire ignition and to achieve full coverage by using a minimum number of sensors. The challenge lied in designing and development of a suitable smoke sensor which meets stringent vehicular dynamic applications such as varying ambient operating temperatures, humidity, vibrations, mechanical shock, dust, etc. As the active fire protection is getting more and more important for electric vehicles in general and more so in battery pack assembly. In a Battery pack, cells can vent out due to overcharge/ over discharge/ internal cell fault / ageing / long period of storage. In case of such an eventuality a Smoke sensor located at a strategic location inside the battery pack assembly is designed to sense the Smoke and give a digital signal to the on board vehicle computers. Based on the state of the vehicle, on board computer can take the necessary actions based on the strategy defined in the control logic. Due to the diversity of applications, requirements, and design goals, there is no single, distinctive approach to the design and deployment of smoke sensor available today. This had led to a detailed study and investigation for deployment of battery pack smoke sensor.