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BATTERY
8-3
The temperature correction in specific gravity read-
ing at 80" Fahrenheit is zero. Add .004 specific gravity
points for every 10 degrees over 80°F and subtract
.004 specific gravity points for every 10 degrees under
80°F. All readings must be corrected to 80 degrees
Fahrenheit. Refer to Figure
1
and examples one
and two as follows:
Example 1 -
Hydrometer Reading . . . . . . . . . . . . . . . . . . . .
1.260
Acid Temperature . . . . . . . . 20 degrees Fahrenheit
Subtract Specific Gravity
. . . . . . . . . . . . . . . .
.024
Correct Specific Gravity is . . . . . . . . . . . . . . . 1.236
Example 2-
Hydrometer Reading .....................
1.255
Add specific Gravity . . . . . . . . . . . . . . . . . . . .
.008
Acid Temperature . . . . . . . 100 degrees Fahrenheit
Corrected Specific Gravity is
. . . . . . . . . . . . . 1.263
A fully charged relatively new battery has a specif-
ic gravity reading of 1.260 plus .015 minus .005 (all
batteries for use in temperate climates).
ADJUSTMENT OF ACID GRAVITY
Hydrometer floats usually are not calibrated below
about 1.160 specific gravity and cannot indicate the
condition of a battery in a very low state of charge.
Therefore, it may be necessary to give the battery
several hours charge before a hydrometer reading will
indicate that the battery is taking a charge.
If
the specific gravity of all cells are not within .015
points of the specified value, corrected to 80"F, at
the end of a full charge, remove some of the electro-
lyte with the hydrometer and add a like amount of
distilled water to reduce the gravity if too high, or
add 1.400 Specific Gravity acid to raise the specific
gravity,
if
too low. Continue the charge so as to give
the electrolyte a chance to mix and then read the
gravity after another hour of charge to note the effect
of the additions. Continue this adjusting procedure
until the gravity is brought to the desired value by
charging for one hour after each adjustment.
Never adjust the specific gravity of any battery
cell which does not gas freely on charge. Unless elec-
trolyte has been lost through spilling or leaking, it
should not be necessary to add acid to a battery dur-
ing its life. Acid should never be added unless one i s
certain that the cell will not come up to normal grav-
ity by continued charging. Always make the tempera-
ture correction for hydrometer readings, as warm
electrolyte will read low and this might be mistaken
for failure of the battery to rise normally in gravity.
It could also be falsely concluded that the battery
would not take a full charge.
HIGH RATE DISCHARGE TEST OF
BATTERY CAPACITY
Satisfactory capacity tests can be made only when
NY 837A
Fig. 2-High
Rate Discharge
res
the battery equals or exceeds 1.220 specific gravity
at 80 degrees Fahrenheit. If the reading is below 1.220
the battery should be slow charged until fully charged
in order to secure proper test results.
Test Procedure
(1) Turn the control knob of the battery starter
tester to the
OFF
position.
(2) Turn voltmeter selector switch to the 16 volt
position on test units so equipped.
(3)
Connect the test ammeter and voltmeter posi-
tive leads to battery positive terminal. Connect the
ammeter and voltmeter negative leads to the battery
negative terminal (Fig. 2).
NOTE: The voltmeter clips must contact the bat-
tery posts or cable clamps and not the ammeter
lead clips.
(4)
Turn the control knob clockwise until th.e am-
meter reading is equal to three times the ampere
hour rating of the battery.
(5) Maintain this load for 15 seconds; the voltmeter
should read 9.5 volts or more, which will indicate
that the battery has good output capacity.
(6) After the 15 second test, turn control knob to
the OFF position.
If the voltage in the "High Rate Discharge Test"
was under 9.5 volt, the battery should be
test charged
to determine whether the battery can be satisfactor-
ily charged.
Churging The Buttery
Three Minute Churge Test (Fig.
31
NOTE: This
test should not be used if battery tem-
perature is below
60 degrees F.
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