State of Health — SoH

The State of Health (SoH) describes a battery's health relative to its initial state and is usually expressed as a percentage. Since it cannot be measured directly, it is often determined based on the available capacity, the internal resistance, or a combination of several state variables. Unlike the State of Charge (SoC), the SoH does not indicate the current charge level, but rather the long-term change resulting from calendar and cycle aging. A reliable SoH is crucial for evaluating the performance, usable capacity, and remaining service life of a battery storage system.