A method for online capacity estimation of lithium ion battery cells using the state of charge and the transferred charge

In this article a method to estimate the capacity of individual lithium ion battery cells during operation is presented. When having two different states of charge of a battery cell as well as the transferred charge between these two states, the capacity of the battery cell can be estimated. The method is described in detail and validated on a battery cell with a current pulse test cycle. It is then applied to a real life cycle, the accuracy is analyzed and discussed.