The results reveal that the variations of density with SoC differs for the posolyte and the negolyte. Thus, while the posolyte density slightly increases during charge, that of the negolyte decreases by up to 2%. Compared to density, viscosity variations are more pronounced in relative terms. They are affected by all the studied parameters, the SoC being the most relevant (without considering extreme unrealistic variations in the other parameters). This effect is amplified with higher vanadium concentrations and lower temperatures. For instance, at 10 • C, a fully charged 1.83 M negolyte exhibits a viscosity that is 38% lower than when discharged.