METHODS AND SYSTEMS FOR DETERMINING AVERAGE OXIDATION STATE OF REDOX FLOW BATTERY SYSTEMS USING THE OPEN CIRCUIT VOLTAGE

A method for determining a storage capacity or average oxidation state (AOS) of a redox flow battery system including an anolyte and a catholyte includes discharging a portion of the anolyte and catholyte of the redox flow battery system at a discharge rate that is within 10% of a preselected discharge rate; after discharging the redox flow battery system, determining an end OCV; and determining the storage capacity or AOS from the end OCV. Other methods can be used to determine the storage capacity or AOS using a measured OCV.