Specific gravity of a substance is the comparison of density of the substance with the density of pure water.
Specific gravity = Density of the substance / density of pure water.
= kg / cm2 kg / cm2
= (No unit)
Specific gravity is only number.
It has no unit. Specific gravity of pure water is one.
Specific gravity of fully charged lead acid battery is 1.215. Specific gravity should always be corrected to 27°C.
Corrected specific gravity is equal to indicated specific gravity ± (t - 27°C)*0.0007.
Indicated specific gravity = 1.205 and ‘t’ means electrolyte temperature.