U.S.-manufactured lead-acid batteries are considered fully charged when the specific gravity reading is between 1.275 and 1.300 A 1/3 discharged battery read about 1.240 and a 2/3 discharged shows a specific gravity reading of about 1.200 when tested by a hydrometer at an electrolyte temperature of 80ํF However, to determine precise specific gravity readings, a temperature correction should be applied to the hydrometer indication. [Figure 9-37] As an example, for a hydrometer reading of 1.260 and electrolyte temperature of 40ํF, the corrected specific gravity reading of the electrolyte is 1.244