DISTRIBUTION SYSTEMS - ELECTRICA L POWE R SYSTEM
Battery - Check (A.30.A.83 - F.40.A.11)
435, 445, 445CT
Ahydrometerisusedtocheckthespecific gravity (weight) of the electrolyte. The specific gravity is an indication of
the level of charge for each cell.
Hydrometers are made to show the correct specific gravity when th e tempera ture of the electrolyte is 26.7 °C 80 °F).
When you check the spe ci fic gravity, you must know the temperature of the electrolyte. If your hydrometer does
not have a thermometer, get a thermometer to check the temperature of the electrolyte. The thermometer must
indicate a high temperature of at least 52 °C 120 °F).
NOTE: To correctly test a battery, do each part of the battery test until you know the condition of the battery.
1. Remove enough electrolyte from a cell so that the
float is free in the tube.
NOTE: If the specific gravity cannot be checked without
first adding water to the cell, the battery must be charged
for 15 minutes at 15 to 25 amperes to mix the water with
theelectrolyte. Thencheckthespecificgravity.
2. Read the floa t.
3. Read the thermo meter. If the reading is above
26.7 °C (8 0 °F) add specific gra vity p oints to the
reading for
specific gravity. If the reading is below
26.5 °C (8 0 °F) subtract specific gra vity points from
the reading for specific gravity. See the following
illustrat
ion and add or subtract specific gravity points
as needed.
(1) Temperature in F
(2) Tem p e r
ature in C
B790863 1
4. Make a r ecord of the corrected speci ficgravity
reading for each cell.
5. If the difference between the high reading and the
low reading is 0.050 or more, charge the battery and
check the specific gravity again. If after charging,
the difference is st ill 0.050 or more, install a new
battery.
6. The corrected specific gravity reading shows the
level of charge for the cell. The level of charge must
be at
least 75 % in each of the cells. In maintenance
free batteries the level of ch arge is at least 75 %
if the corrected specific gravity reading is 1.240 or
hig
her. In all other batteries the level of charge is at
least 75 % if the corre ct ed specific gravity reading
is 1.230 or higher.
7. If the difference between the high reading and the
low reading is less than 0.050, and the level of
change is at least 75 % in all of the cells, do the
Capacity (Load) Test.
1 04/05/2005
A.30.A / 93
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