Cross-Battery State-of-Health Estimation of Lithium-Ion Batteries Using Leave-One-Battery-Out Validation and Machine Learning
Abstract
Accurate state-of-health (SOH) estimation is essential for improving the safety, reliability, and operational efficiency of lithium-ion batteries used in electric vehicles and renewable energy storage systems. Although numerous machine learning approaches have been proposed for SOH prediction, many studies evaluate their performance using randomly divided training and testing datasets, which may overestimate the generalization capability of the developed models. This study presents a cross-battery SOH estimation framework based on Leave-One-Battery-Out (LOBO) validation using the NASA battery degradation dataset. A comprehensive set of twenty-one statistical and physics-inspired features was extracted from voltage, current, temperature, discharge time, and energy measurements to characterize battery degradation behavior. Four regression models, namely Random Forest (RF), Least Squares Boosting (LSBoost), Long Short-Term Memory (LSTM), and Support Vector Regression (SVR), were trained and evaluated under the LOBO validation strategy, where each battery was used once as an unseen test battery while the remaining batteries were employed for training. Model performance was assessed using Root Mean Square Error (RMSE), Mean Absolute Error (MAE), and the coefficient of determination (R²). The experimental results demonstrated that the RF model achieved the best overall performance with an average RMSE of 0.0342, an average MAE of 0.0305, and an average R² of 0.8654. LSBoost and LSTM produced competitive prediction accuracies, whereas SVR exhibited poor cross-battery generalization with a negative average R² value. Furthermore, feature importance analysis revealed that VoltageRMS, MeanVoltage, Energy, MeanPower, and DischargeTime were the most influential variables affecting SOH estimation. The proposed framework provides a practical and reliable methodology for evaluating machine learning models under realistic operating conditions and highlights the importance of cross-battery validation for developing robust battery health prediction systems.
Keywords
References
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Details
Primary Language
English
Subjects
Electrical Energy Storage, Electrical Engineering (Other)
Journal Section
Research Article
Authors
Early Pub Date
July 31, 2026
Publication Date
August 31, 2026
Submission Date
July 16, 2026
Acceptance Date
July 28, 2026
Published in Issue
Year 2026 Volume: 10 Number: 1