(1) Inspect the top of the batteries very carefully and clean them if
needed. They must be kept clean to prevent them from discharging through collected
dirt, etc. To clean, tighten the vent plugs and wash the batteries with a brush
dipped in an alkaline solution, such as a mixture of bicarbonate of soda (baking
soda) and water. Foaming will occur due to the reaction between the cleaning
solution and battery electrolyte. 'After the foaming stops, rinse off the
batteries with clean water and wipe dry with a clean cloth.
(2) Inspect the battery terminals to see that they are clean and the
cable clamps tight and free of corrosion. If they are corroded, remove the cable
clamps and clean the clamps and battery posts with a solution as described above.
Then reconnect and tighten the cable clamps. Coat the terminals with a light coat
of general purpose grease to fight off corrosion. Dirt will collect on the grease,
but it can be removed each time the batteries are cleaned and the terminals then
recoated with grease.
(3) Remove and inspect the vent plugs to see that the ventholes are
open. Use a short length of stiff wire to run through the ventholes to make sure
they are not plugged.
(4) Inspect the electrolyte level and add water if it is low. Filling
instructions are usually located on the vent plugs or the cell covers. When
correct, the electrolyte level will be at least 3/8 of an inch above the plates.
Distilled water should be used to fill batteries if it is available; if it is not
available, the second choice is rainwater. Do not store battery water in metal
containers. Minerals that are found in water from streams, wells, or water stored
in metal containers can damage and shorten the life of a battery. Water that is
used for drinking purposes can be used, but only when distilled water or rainwater
is not available. A battery will be damaged less by using clean water that has
some minerals than by letting the electrolyte level drop below the top of the
plates.
(5) Check the specific gravity of each cell with a hydrometer.
b. Battery capacity is greatly reduced by low temperatures because the
electrolyte thickens and is less active. In order to perform satisfactorily in
cold weather the battery must be kept in peak condition, so when the temperature
drops you will have to keep a closer watch on the battery. In cold weather do not
let the specific gravity drop below 1.250. The electrolyte is subject to freezing;
the exact freezing point depends on the specific gravity. In a fully charged
battery the electrolyte will freeze at -90. As the specific gravity drops, the
freezing point rises. Figure 7 shows the freezing point for various specific
gravities. If the battery electrolyte does freeze, the ice forces active material
from the plates and can crack plates and containers. Let a frozen battery thaw out
in a room at normal temperature before charging. In this way the battery can be
saved if freezing has not already caused too much damage.
Figure 7.
Specific gravity and freezing point.
OS 010, 7-P10
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