Pattern-aware transformer for SOC estimation in IoT-based battery management systems: Toward energy-efficient and interpretable modeling

Accurate estimation of the State of Charge (SOC) is essential for enhancing the efficiency and reliability of Battery Management Systems (BMS) in Internet of Things (IoT) applications. This study introduces the Pattern-Aware Transformer Model (PATM), an interpretable framework for SOC prediction in Float-Nominal (FN), Constant-Current (CC), and Energy Release (ER) scenarios. PATM extends the standard Transformer architecture by incorporating a pattern embedding mechanism that explicitly encodes operating conditions and directs adaptive attention allocation. A feature engineering pipeline that combines mutual information (MI) ranking and principal component analysis (PCA) reduces dimensionality while preserving physically relevant variables. On real-world data, PATM achieves an RMSE of 2.08 × 10−3 and an R2 of 0.9998, outperforming the Long Short-Term Memory (LSTM) and Gated Recurrent Unit (GRU) baselines. Compared with single-scenario CC modeling, multi-scenario learning reduces RMSE, MAE, MSE, and MAPE by 54.9%, 80.1%, 79.6%, and 75.9%, respectively. Ablation studies further demonstrate that removing the embedding module increases RMSE by 2.4%, MAE by 17.8%, and MSE by 4.9%, while leaving R2 nearly unchanged. This indicates that the embedding mechanism enhances cross-scenario robustness and error stability. SHapley Additive exPlanations (SHAP) analysis and attention visualizations reveal the model’s dependence on physically relevant factors, including temperature gradients, voltage fluctuations, and internal resistance.