Battery management systems (BMS) monitor the traction batteries of electric vehicles during operation. However, conventional BMS available on the market typically only provide a rough overview based on voltage, current, and temperature. This makes it difficult to detect damage or ageing processes in the battery or individual battery cells.

For this reason, the EU- and Switzerland-funded project ‘Nemo’ brought together TU Graz, the University of Brussels, Infineon Technologies Austria, the engineering service provider IAV, and other partners to develop a novel BMS that delivers far greater insights into batteries and battery cells. The goal was to enable real-time monitoring of battery safety, lifespan, and performance directly within the vehicle’s system.

“The battery management system is an important tool for operating electric vehicles more safely and sustainably,” said Christoph Drießen from the Vehicle Safety Institute at TU Graz. “If we recognise faults and damage to individual battery cells at an early stage via the BMS, many dangers can be avoided. And thanks to the monitoring of the ageing process of each individual cell, their service life can also be extended substantially through intelligent control.”

A team at TU Graz focused primarily on battery safety aspects, while the algorithms and models for lifespan and ageing were developed at the University of Brussels. Specifically, the team investigated battery cells at the Graz Battery Safety Centre that had been mechanically deformed to simulate scenarios such as parking damage. Using this laboratory data, the researchers trained self-developed models and algorithms to enable the BMS to independently detect damage and indicate necessary maintenance.

To obtain the required data from inside the battery cells, the team used electrochemical impedance spectroscopy (EIS), a sensing technology that measures the electrical resistance within the cells while the vehicle is in operation.

The researchers see clear advantages in this new method compared to existing BMS: “Up to now, a test only showed how much the capacity has decreased compared to the original battery condition,” said Drießen. “But the new models also give us an insight into the changes within the cells as they age. This enables adjustments that are beneficial for performance, service life and safety.”

The researchers expect that such an advanced BMS, despite its numerous new functions, would not be significantly larger or heavier than current systems. However, additional sensors and appropriately adapted integration into the BMS are required for the EIS measurements. In a follow-up project, the partners plan to further develop their invention and work towards industrial application. A module-level demonstrator has already been built as part of the current project.

tugraz.at