Incremental Capacity Analysis for Electric Vehicle Battery State-of-Health Estimation

The State-of-Health (SoH) of Electric Vehicle (EV) batteries is important for the EV owner and potential buyer of second hand EVs. The Incremental Capacity Analysis (ICA) has by other researchers shown to be a promising SoH estimation method for lithium ion batteries. In order to be practical useable do the method however, need to be feasible on pack or EV level and not only on individual cell level. The purpose of this paper is to demonstrate the feasibility of the ICA method on real EVs. Nickel Manganese Cobalt (NMC) based cells for the BMW i3 EV has been tested both on cell level and on car level. The results are consistent and the characteristic peaks and valleys of the ICA on car level matches with the same on cell level. It is therefore concluded that the ICA method also is applicable on car level for battery SoH estimation.