OCV aging refers to the decline or shift in the open circuit voltage of a battery over its lifespan. This change in OCV is due to the irreversible chemical and physical changes within the battery as it ages. Factors contributing to OCV aging include loss of active materials, formation and growth of the solid-electrolyte interface (SEI), and other degradation mechanisms. As the battery ages, its maximum and minimum OCV values can shift, affecting its total usable capacity. A shift in OCV values can make state of charge estimation more challenging, potentially leading to reduced battery performance and lifespan.