The computational cost for all-vanadium redox flow batteries (VRFB) models that seek to capture the transport phenomena usually increases with the number of spatial dimensions considered. In this context, we carry out scale analysis to derive a reduced zero-dimensional model. Two nondimensional numbers and their limits to support the model reduction are identified. We verify the reduced model by comparing its charge–discharge curve predictions with that of a full two-dimensional model. The proposed analysis leading to reduction in dimensionality is generic and can be employed for other types of redox flow batteries.