Investigation of C-rate and post-discharge rest effects on voltage recovery and capacity in Li-ion battery pack for LEO satellite applications

Lithium-ion batteries are extensively employed in LEO satellites because of their high energy density, lightweight design, and superior cycle efficiency; however, their on-orbit performance is strongly influenced by discharge rate and post-discharge voltage relaxation during repetitive eclipse-sunlight cycling. In this study, an experimental investigation was conducted on an 8s6p Li-ion battery pack with a nominal capacity of 19.2 Ah and nominal voltage of 28.8 V. The battery was tested under three different discharge rates–C/20, C/10, and C/5–followed by rest periods of 30 minutes, 1 hour, and 2 hours. The results indicate that increasing the C-rate significantly enhances the voltage recovery amplitude, whereas extending the rest duration provides only marginal improvement in effective capacity. The voltage relaxation behaviors is well described by a double-exponential model. The proposed model (R2> 0.99, RMSE < 0.03) confirms the coexistence of fast and slow relaxation processes driven by Li-ion redistribution and electrode structure relaxation. These findings demonstrate that orbit-aware management of discharge rates and rest phase can improve voltage stability and effective energy utilization without increasing system mass or volume, offering practical guidance for battery management strategies in power-constrained LEO missions, including CubeSats and nanosatellites.