ORALS

Since the number of electric vehicles has raised substantially, the market for Lithium- Ion battery (LiB) has also a vast expansion. Industry is using state of health to indicate the reliability of LiB and its associated system. However, this cannot provide proper prediction to the LiB pack reliability according to the system reliability theory that has long been established without considering the sharing current effect in the parallel sub-structure and the cell diversities in a pack. This work illustrates a statistical modelling procedure of Lithium-Ion battery pack useful life based on the experiments of cell degradation and physical effects of parallel sub-structure in a pack. The suggested statistical capacity fading (SCF) model with fixed and random coefficients (mixed effect) was based on a simplification of the electrochemistry- based electrical (ECBE) model which had a strong support from electrochemistry theory. Our method demonstrated that less than 50% of their entire life cycle data is sufficient for its distribution determination. Several scenarios of structure connections in a LiB pack were illustrated for the computation of the corresponding reliability and life span. The critical condition to prolong the lifetime of a LiB pack was the similar discharge current rates of cells in the pack.