So much is riding on the reliability of the batteries used in electric vehicles – not least public trust in electromobility, as the industry shifts gear away from the combustion engine. But the fact is, conventional lab testing for these batteries is inadequate. The challenge is how to simulate the impact of electrical, mechanical and environmental stresses in real-world conditions to test the performance of the battery.
At the moment, a “real-world” trial is not even possible until a drivable prototype of the vehicle in question has been produced. By that stage, however, any subsequent modifications to the battery will cost a lot of time and money. That is why the Fraunhofer Institute for Structural Durability and System Reliability (LBF) in Darmstadt have come up with a new kind of “hardware-in-the-loop” test in a project called MEF-BILL.
“We are now bringing the road into the laboratory and combining our multi-physical testing rig with a computational vehicle simulation. This means we can test batteries under realistic conditions before a prototype vehicle physically exists,” explains Dr Riccardo Bartolozzi, the LBF’s expert on numerical system simulation, in a .
The MEF-BILL system is capable of simultaneously testing electrical loads, vehicular motion, and climatic aspects – the three critical and interdependent factors affecting a battery’s performance which could previously only be tested separately. The LBF testing environment can simulate different kinds of roads, manoeuvres and driving conditions, taking into account factors like speed and payload, using a real-time, computerised model of the vehicle which is connected to the apparatus. It is able to recreate random variations in the journey such as load peaks, which happen in a matter of seconds.
The battery’s parameters are continuously tracked and fed back into the simulation. This kind of real-time, loop testing is as close as it is possible to get to an actual road test.