Lithium-ion cell-to-cell variation during battery electric vehicle operation

Obtained results are compared to vehicles' operational data to provide recommendations with the aim to minimize the increasing parameter spread. However, neither temperature gradients in the battery pack nor an insufficient balancing procedure were determined. As the appearance of cells with suspicious parameters could not be assigned to local weak spots of the battery pack, a random and inevitable type of origin is assumed. Hence, the battery management system must ensure to detect outliers in a reliable manner and to balance resulting drifts of cells' states of charge to guarantee a safe battery storage operation.