Vanadium Redox Flow Battery: OCV State-of-Charge Estimation

A vanadium redox flow battery stores energy as the oxidation state of vanadium ions in two circulating electrolyte tanks rather than in a solid electrode, which is why its state of charge can be read directly from open-circuit voltage via the Nernst equation. This simulator renders the two tanks and their stack in 3D, lets you charge or discharge the cell with a real applied-current slider, and tracks the true state of charge in each tank separately alongside the single-voltage state-of-charge estimate a real battery-management system would compute. Push the electrolyte temperature away from the BMS's assumed reference, or turn up membrane crossover so the two tanks' vanadium ratios drift apart, and watch the estimation error grow — a genuine, well-documented limitation of OCV-based SoC tracking in redox flow batteries.