In this paper, a dynamic model is developed based on different crossover mechanisms (diffusion, migration and electro osmosis) for each of the four vanadium ions, water and protons in the electrolytes. . Vanadium redox flow batteries are gaining great popularity in the world due to their long service life, simple (from a technological point of view) capacity increase and overload resistance, which hardly affects the service life. However, these batteries have technical problems, namely in balancing. . Interfaces 2021, 13, 30, 36605 L. Power Sources, 343, (2017), 536 We demonstrate reliable vanadium flow battery SoC measurement and H2 gas detection using acoustic method. The different vanadium ions move unsymmetrically through the membrane and this leads to a build-up of vanadium ions in one. . Therefore, managing battery health status is necessary to maintain long cycle life and high energy efficiency. SOC is a critical indicator of battery health in a redox flow battery.