A Reduced-Order Lumped Model for Li-Ion Battery Packs during Operation

Abstract

Modeling heat distribution in Li-ion battery packs can be challenging, especially if the battery pack is large and the cells are operated at high C-rates, which usually requires high-order physics-based mathematical models. Reduced and simplifying models can, however, be used at lower rates. This paper presents a fast novel reduced lumped model (RLM) that can be used to calculate the temperature increase during the high-current discharge of cylindrical Li-ion cells in a subscale of a battery pack. By reducing the PDE utilized to calculate the state of charge (SoC) to ODE’s and solving them analytically, the reduced model can be a very reliable and fast tool for calculating the temperature distribution in battery packs. The voltage was calculated by considering the charge overpotential, the ohmic overpotential, and the activation overpotential, while the properties of the parameters are dependent on the temperature following an Arrhenius-dependency. Comparing with experimental data, the model showed a good prediction of the temperature readings showing good potential in using the model for battery packs operating at high C-rates (>2 C).