Caution: In freezing temperatures, water should be added immediately before the engine-compressor is
started. This will permit the water and electrolyte to be thoroughly mixed by the charging process and
will prevent the added water from freezing.
c. Checking Specific Gravity. Check the specific gravity of the electrolyte with a reliable hydrometer and a
thermometer. All cells will have an approximate gravity reading of 1.285 when fully charged and 1.150 when completely
discharged. Because specific gravity varies with temperature, all hydrometer readings should be corrected in accordance
with the chart shown in figure 30. Recharge the batteries if the corrected specific gravity reading is below 1.225 in warm
weather or 1.250 in cold weather.
(2)
Figure 30. Hydrometer correction chart.
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