On-Orbit Performance Analysis of Lithium-Ion Batteries Based on NCA System for MEO Satellites

Faced with the complex space electromagnetic environment, the long solar illumination periods of medium-Earth-orbit (MEO) satellites, and the unique operating limitation under which the batteries operate under shallow charge–discharge cycles, this paper proposes a dedicated life evaluation method suitable for MEO satellite batteries. The proposed method quantifies battery performance degradation by analyzing the statistical correlation between the discharge capacity and discharge cut-off voltage during eclipse phases. Using seven years of on-orbit-measured data covering 14 eclipse seasons, we build prediction models for the cut-off voltage via Random Forest and XGBoost, with the eclipse season index and discharge capacity set as model input features. The mean squared error (MSE) of both models is lower than 0.003, demonstrating the high reliability of the modeling framework. Under the condition of a fixed discharge capacity, no obvious battery degradation exceeding the measurement uncertainty is detected within the observation period. The magnitude of potential voltage degradation is comparable to or even smaller than the 2 mV acquisition uncertainty, such that no measurable degradation phenomenon can be identified in the available dataset. At present, long-term on-orbit-measured data of MEO satellite batteries are scarce in engineering research. This study provides valuable full-measurement data support for the optimized design, autonomous on-orbit management, and life evaluation of NCA lithium-ion batteries and fills the gap in long-term on-orbit datasets for MEO satellite power systems.