Battery Safety Sensor detects cell venting

A new battery sensor is able to detect the chemical venting that occurs within lithium-ion cells as a precursor to potentially catastrophic thermal runaway.

Developed by Bristol-based Metis Engineering, the Battery Safety Sensor is a CAN (Controller Area Network) based sensor that can be mounted inside EV battery packs. The device is designed to pick up a range of environmental parameters, including hydrogen, volatile organic compounds (VOCs), pressure change, humidity, dew point and absolute water content.

These data points are cross-checked with other inputs such as cell temperature to monitor for venting in real-time. If venting of a cell is detected, the CAN interface can then direct the vehicle’s engine control unit (ECU) to kill the load to the battery, preventing thermal runaway that could propagate across the battery pack and potentially threaten the lives of those inside the vehicle.

“Our Battery Safety Sensor is a game changer!” said Metis Engineering’s managing director Joe Holdsworth. “It will enable EVs to be safer than ever before. The technology packed into the sensor module makes it a unique and affordable addition to every battery pack. An electric car might have two sensors, whilst an electric bus would have six to eight, depending on the number of battery packs they distribute around the vehicle and the internal air volume of the packs.

The sensor also includes an accelerometer so it can monitor shock loads and impact duration of up to 24G. According to Metis, the device could be fitted to battery packs during manufacture in order to monitor cell integrity from factory to being fitted in an EV. Once in situ in a vehicle, the sensor will continue to monitor the pack’s health via the accelerometer. Should an EV be involved in a collision, the sensor will show whether the pack experienced loadings above safe levels and for what duration informing decisions around vehicle safety and service.

“Being able to life a battery pack right from manufacturing to fitting into a vehicle is possible thanks to the sensor’s accelerometer,” explained Holdsworth. “You’ll know if the pack was dropped in transit or if once fitted to a vehicle, what loadings it experienced during a collision. EV insurers will be very keen to ascertain if the high-value battery packs need to be serviced or written off.”