In the referenced works, we hypothesize that a significant source of measurement error may come from the sample preparation methods. Previous research relied solely on electrochemical measurements and visual color cues to prepare solutions at specific SoCs, omitting more precise characterization techniques such as UV-Visible spectroscopy . To summarise, the gaps in the literature call for open access, precise and extensive data regarding the physical properties of vanadium electrolytes, especially those describing their variations with the SoC. This paper aims to provide a comprehensive and accurate database containing density and viscosity values for both positive and negative electrolytes, measured at well defined compositions, while varying the relevant parameters, i.e., the SoC, total vanadium and sulfates concentrations, and temperature.