LiFePO4 Battery Thermal Modeling: Bus Bar Thermal Effects⁎

Lithium iron phosphate (LFP) batteries are ideal for electrification of off-road heavy-duty vehicles with less concerns on the system weight. However, the limited battery life aggravated by the long working hours is a primary concern for some of-road applications such as construction equipment. Temperature is one of the main influencing factors in battery aging. Therefore, accurate prediction of temperature dynamics with fast lumped parameter models is essential and can be used for long-term analysis. This paper introduces a thermal model for pack of cells, with each cell represented by surface and core temperature states. We derived model parameters from experimental thermal cycling data, emphasizing the significance of reversible entropic heat generation for capturing faster dynamics. Furthermore, our work highlights the errors introduced by neglecting the bus bar thermal effects when extending a single-cell model to a cell pack. Our proposed solution incorporates the conduction between cell cores via the bus bar and accounts for heat dissipation through convection from the bus bar to surrounding air.