Online estimation of the state of charge and state of health of a vanadium redox flow battery

This study presents an online algorithm capable to simultaneously estimate the state of charge and state of health of a vanadium redox flow battery. Starting from a general electrochemical model, some order reductions are carried out considering different conservation laws. Based on these low-order models, the observer is designed considering the terminal voltage of the battery. This observer is firstly analyzed using numerical tools. Secondly, an experimental validation is carried out with real data provided by a vanadium redox flow battery stack, consisting on current and voltage measurements. [Display omitted] •The model proposed considers mass and charge conservation principles.•An online observer for both SOC and SOH indicators is developed.•SOC and SOH estimations are obtained by only measuring the battery voltage.•Numerical and experimental data has been used to validate the observer.•Results show the possibility to properly estimate the SOC and SOH in real time.