Cadillac 60 Series 1963 Shop Manual page 287

12-6
ELECTRICAL SYSTEM
Correction can be made for temperature by add-
ing .004, usually referred to as four "points of
gravity", to the hydrometer reading for every 10°
F. that the electrolyte is above 8Q°F. or subtract-
ing .004 for every 10°F. that electrolyte is below
80°F. Figure 12-5 shows the exact correction fig-
ure to use for any temperature above or below 80°
F., the three steps used in obtaining the corrected
or true specific gravity, and two examples show-
ing how it is determined.
If the electrolyte temperature is not too far from
the 80°F. standard, or if only an approximate idea
of specific gravity reading is required, it will not
be necessary to make the temperature correction.
Hydrometers are available which have a built-in
thermometer and temperature correction scale
similar to Fig. 12-5. This type of hydrometer
simplifies obtaining a true specific gravity read-
ing.
4. Hold hydrometer vertically and draw in just
enough liquid from battery cell so that float is
free floating. Hold hydrometer at eye level so
that float is vertical and free of outer tube, then
take reading at surface of liquid. Disregard the
curvature where the liquid rises against float stem
due to surface tension.
5. Avoid dropping fluid on car or clothing as it
is extremely corrosive. Any liquid that drops
should be washed off immediately with soda
solution.
4. Full Charge Hydrometer Test
NOTE: The full charge hydrometer test
should not be used unless the battery has been
tested and found good by the light load test.
1. Be certain that the battery is fully charged.
When using a hydrometer, observe the following
points:
1. Hydrometer must be clean, inside and out, to
insure an accurate reading.
2. Hydrometer readings must never be taken
immediately after water has been added. The
water must be thoroughly mixed with the electro-
lyte by charging for at least 30 minutes.
3. If hydrometer has built-in thermometer, draw
liquid into it several times to insure correct tem-
perature before taking reading.
ELECTROLYTE
TEMPERATURE (F)
0
MPER
:TROL
HERM'
©
TAKE TEMPERATURE
l 0 0 <
O F ELECTROLYTE
W I T H THERMOMETER 9 0 «
TAKE SP. GR. O F
ELECTROLYTE
W I T H HYDROMETER
80'
5 0
EXAMPLE A:
4
°
<
120° F. so«
TEMPERATURE
HYDROMETER
READING = 1.230
CORRECTION
(« 120° F. - + . 0 1 6
TRUE SPECIFIC
GRAVITY = 1.246
20<
SPECIFIC GRAVITY
CORRECTION
©
CHANGE HYDROMETER
READING BY AMOUNT
SHOWN ON THIS SIDE
OPPOSITE THE
ELECTROLYTE
TEMPERATURE
- o i « EXAMPLE B =
-O2O TEMPERATURE = 0° F.
HYDROMETER
READING = 1.230
CORRECTION
(a 0° F. = - .032
02 8
T R U E
SPECIFIC
GRAVITY = 1.198
.038
— -.0 36
.040
2. Measure the specific gravity of the electro-
lyte in each cell and compare the readings with the
following:
a. If cell readings range between
1.310, battery is ready for use.
1.230 and
Fig. 12-5 Specific Gravity Temperature Correction Scale
b. If any cell reads less than 1.230 and battery
has been in service 3 months or less, battery is
good, but it has been improperly filled with
electrolyte or water and will give poor perform-
ance. To correct this condition, empty the electro-
lyte from the cell reading less than 1.230 and refill
with electrolyte having a specific gravity of 1.265.
c. If any cell reads less than 1.230 and the bat-
tery has been in service three months or more, it
should be replaced.
d. If any cell reads above 1.310, the battery
may be returned to service. However, specific
gravities above 1.310 are harmful to the battery
and will cause an early failure. Such high read-
ings are caused by the improper addition of elec-
trolyte. Adjusting the specific gravity by pouring
out the old solution and replacing it with electro-
lyte of the correct specific gravity will not cor-
rect the damage that has been done.
5. Causes of Low Battery
Conditions
Common causes of low battery conditions other
than those due to a defective battery are listed
below, and should be investigated when there are
indications that the car has a consistently low
battery.
1. Excessive use of accessories with the engine
not running.
2. Leaving lights on or doors open.
3. Improper installation of accessories.