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
