​The best-known and most frequently-occurring safety problem plaguing lithium-ion batteries is thermal runaway. And there is no shortage of research to find ways to detect thermal runaway early on to make the batteries safer.

The internal temperature of the battery is the main factor in thermal runaway. And yet, there is no way to actually get inside a battery during operation to monitor the temperature directly. So, researchers at Leti and Liten found a workaround: an electrical impedance measurement, which is related to temperature, but which had never before been embedded in the battery-management electronics.

The researchers came up with a clever way to use the battery’s existing electronics. By adapting the sensors, they were able to create an effective electrical impedance measurement system at a reasonable additional cost over traditional battery-management electronics.

The algorithm uses the data from the sensors to calculate the battery’s internal temperature and other indicators like maximum available power (which can be useful for the driver of an electric vehicle to know before passing another car, for instance).

Two ongoing EU projects are pursuing this research. The system developed, which has been the subject of five published articles and a patent application, could one day be integrated into electric vehicle battery management systems (BMS).