Optimization of In-Situ State of Health Analysis Using Conventional Charging Infrastructure Considering Workshop Applications

Estimating the state of health (SOH) of traction batteries in-situ, using conventional charging infrastructure e.g. during a routine workshop inspection, has the potential to be a forecasting tool for end users and fleet operators. Following a previous feasibility study, in which two in-situ methods for determining the condition of an electric vehicle (EV) were successfully tested and compared. Both methods can be used to determine the capacity, internal resistance and open-circuit voltage (OCV). Based on simulation results from real driving data, the pulse profile turned out to be the better charging method. The pulse profile can be explicitly optimized regarding the number of support points, relaxation time and pulse height. The authors analyze the effects analytically and again simulatively using the RINT model to optimize the result regarding accuracy and time needed. In addition, technical limitations in recording vehicle data and controlling charging processes for electric vehicles using conventional AC and DC charging infrastructure are highlighted.