Early-stage Battery Thermal Management System (BTMS) design can be constrained by limited manufacturer data, resulting in the use of steady-state thermal assumptions. An analytical methodology is introduced to extract the real-time cell resistance, instantaneous efficiency, and transient heat generation directly from standard constant-current discharge curves, and Open Circuit Voltage (OCV) profiles. By evaluating the time-dependent voltage differential against current, equivalent cell resistance and transient heat generation are computed without explicit ohmic measurement or calorimetric testing. This enables direct, real-time coupling of electrical and thermal models. Application to an NMC chemistry cell demonstrates concentration losses dominate below a 20% State-of-Charge (SOC), increasing transient heat generation, and decreasing instantaneous efficiency. Extracting the time-dependent electro-thermal parameters provides the required quantitative inputs for benchmarking cells & accurately sizing BTMS cooling capacities.
Citation: N. A. Ingarra, K. J. Kobus, J. G. Kobus, “Deriving Instantaneous Electro-Thermal Parameters and Heat Generation from Constant-Current Discharge Data,” In Proceedings of the Ground Vehicle Systems Engineering and Technology Symposium (GVSETS), NDIA, Novi, MI, Aug. 11-13, 2026.