The traction battery is the most critical and expensive component of an electric vehicle (EV), directly dictating the vehicle’s range, performance, and resale value. As the EV market matures in 2026, understanding the distinction between State of Charge (SoC)—the remaining energy for the current trip—and State of Health (SoH)—the permanent capacity remaining compared to the battery’s original state—has become essential for owners and technicians alike. Monitoring battery health is not just about range; it is a critical safety and economic imperative (Njoku et al., 2025).

The Science of Battery Degradation

Battery degradation is a complex physical and chemical process. It is primarily driven by mechanisms such as Solid Electrolyte Interphase (SEI) layer growth, lithium plating, and thermal stress (Anandavel et al., 2021). These processes lead to increased internal resistance, which causes voltage drops under load and reduces the total energy the battery can hold (Rao et … READ MORE ...