While portable lithium-ion batteries have been reused for a long time without much public attention, batteries from electric vehicles, which has become the dominant segment in the lithium-ion market, get more and more attention for their potential to be used in other applications. In the last few years corresponding market began to grow exponentially. However, the information about exact prehistory of second-life batteries is hardly available even for the manufacturers, usually only in the form of accumulated data. This data as a rule contains details on operating hours, energy throughput, time spend in different states of charge, power, and temperature ranges. This form of event recording is sufficient for overall monitoring, but not suitable for precise estimation of battery state of health, or determination of remaining useful life. Whereby exactly these two quantities, ideally together with state of safety, must be specified for battery suitability estimation and proper risk assessment before their deployment in the second-life applications.

In this presentation the development of mobile test bench for battery on-site qualification and results of its deployment for EV-battery grading are shown. The advantages and functionalities of test bench are outlined. As well as measurement results for batteries of three different manufacturers are presented. For the data processing two different methods were deployed, the fast time domain impedance measurement method and high-order equivalent circuit model-based parameter extraction. Both deliver almost entire impedance spectrum within a measurement duration of about half an hour, enabling a deep insight into the degradation processes.