TM 5-3825-225-14&P (3)  Disconnect battery cables (5) and remove battery (12) from battery box (10). (4)  Remove battery cables (5) and grommets (13) from battery box (10). b.  Testing Battery Specific Gravity. (1)    Specific  gravity  of  the  electrolyte  (distilled  water  and  acid  solution)  determines  the  temperature  at  which  a battery  will  be  harmed  or  damaged  by  freezing.    Table  4-3  gives  the  freezing  point  of  battery  electrolyte  at given specific gravities. (2)    The  battery  box  is  a  good  heat  insulator  and  the  electrolyte  temperature  will  lag  several  hours  behind atmospheric temperature. (3)  The specific gravity of the electrolyte must be maintained at 1.225 minimum.  The level of the solution should be  at  the  star  level  in  the  cell  covers.    A  fully  charged  battery  has  a  specific  gravity  of  1.255-1.270  at  80°F (270C). (4)  To eliminate the possibility of harmful sulfation of plates, a battery with a specific gravity of 1.225 or less should be recharged. (5)  Table 4-4 shows the effect of temperature on the capacity of a battery. c.  Checking Battery Visually. (1)  If there is any corrosion on the battery or around the terminals, rinse it off with a baking soda and water solution. (2)  Remove any dirt on top of the battery. Table 4-3.  Electrolyte Specific Gravity. Specific Gravity Freezing Point 1.280 -90°F (-68°C) 1.220 -30°F (-34°C) 1.210 -20°F (-29°C) 1.180 -10°F (-23°C) 1.160 0°F (-18°C) 1.140 10°F (-12°C) 1.100 20°F (-7°C) 1.000 32°F (O°C) Table 4-4.  Effect of Temperature On Battery Capacity. State of Electrolyte Percentage Charge Temperature Capacity Full 80°F (27°C) 100 Full 60°F (16°C) 88 Full 40°F (4°C) 75 Full 20°F (-7°C) 62 Full 0°F (-18°C) 45 Full -20°F (-29°C) 20 4-19