PHEV battery ageing study using voltage recovery and internal resistance from On-board data

It is well known that batteries do not perform equally the first day of use than some years later. Their properties are in constant degradation, their capacity fades and the maximum power reduces. Batteries ageing has been widely studied under laboratory controlled conditions for different types of cells. In real life, however, every person has its own driving profile, which is almost unique and unpredictable, making the State of Health during real life cycles highly difficult to accurately estimate. This study presents a methodology for ageing estimation based on data extracted from on-board data-loggers installed in an electric vehicle. When a driver turns off the vehicle, the battery voltage slowly increases until it finally reaches the Open Circuit Voltage (OCV). It has been observed that the recovery voltage transition depends on the temperature and ageing, providing new elements to verify the battery State of Health. Keywords—Ageing, Battery, EV, PHEV, Lithium Ion, On-Board, SOH.