Assessing Lifetime, Performance, and Functionality Impact for CubeSat Battery Packs via Modelling

Batteries are an essential part of CubeSats, and their lifetime is heavily dependent on them. To accurately predict the battery lifetime, cell inhomogeneities and battery pack functionalities are needed to be considered. Thus, in this work, a model is proposed for battery performance and lifetime prediction during various missions, such as orbiting Earth or deep space. The model is based on an electrical circuit model, degradation model, and self-discharge model while allowing to apply cell-to-cell variations to each cell. The need for balancing functionality for non-identical cells was confirmed. Moreover, the influence of battery cell parameters on a battery pack's performance and lifetime was studied individually to assess their significance. The Coulombic efficiency was identified as the most critical parameter that causes SOC imbalance and consequently heterogeneous degradation. Thus, it is suggested to prioritize it when performing cell matching.