What type of study is this?

This is a In Vitro Study study (also classified as: Observational).

August 19, 2025Open Access

Accurate state of charge estimation for INR18650 (NMC) lithium-ion cells using a validated 1RC equivalent circuit model for BMS applications

AYArvind YadavGLA University TTTapankumar TrivediMarwadi University BSB SpoorthiJain University

Key Points

Accurate SOC estimation achieved with an equivalent circuit model, showing minimal errors across tests.
The model demonstrated a maximum error of 0.0439 V over the SOC range from 10% to 100%, highlighting its reliability.
Evaluation included static capacity tests and hybrid pulse power characterization methods, ensuring comprehensive analysis.
This promising approach supports better battery management system implementation, potentially improving user confidence in electric vehicles.

Abstract

With increased penetration of electric vehicle (EV) in conventional transportation it has become important for manufacturer to build faith of customers in their product, specially battery performance. Accurate state of charge (SOC) measurement has now become crucial as most users wants to know the exact range available to them while driving EV. This study explores equivalent circuit models (ECMs) performance for lithium-ion 18650 (NMC) battery, the ECM RC parameters are evaluated by performing static capacity test and hybrid pulse power characterization (HPPC) test. The simulation model performance is compared with the experimental data, the cell open circuit voltage (OCV) errors (maximum absolute error and the root mean square error) are evaluated for different SOC range. Results shows 0.0439 V error for 10% SOC level to 100% SOC level in HPPC test and 0.0166 V error for 10% SOC level to 100% SOC level in long pulse discharge test, thus recommends the use of ECM for most of the practical usable SOC.

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