Dodge ram truck 3500 1996 Service Manual page 354

8A - 6 BATTERY B R
D I A G N O S I S A N D T E S T I N G (Continued)
TEST INDICATOR/STATE-OF-CHARGE
100% 7 5 % O
LOW
100% 7 5 % O
ELECTROLYTE
( ^ )
( ^ ^ ^ ^ ^
®
GREEN
BLACK YELLOW
J958A-6
Fig. 3 Buiit-ln Test Indicator Sight Glass
Built-in Test Indicator or Open Circuit Voltage Test
in this group.
Specific gravity is a comparison of the - density of
the electrolyte to the density of pure water. Pure
water has a specific gravity of 1.000, and sulfuric
acid has a specific gravity of 1.835. Sulfuric acid
makes up approximately 35% of the electrolyte by
weight, or 24% by volume.
In a fully-charged battery the electrolyte will have
a temperature-corrected specific gravity of 1.260 to
1.290. However, a specific gravity of 1.235 or above is
satisfactory for battery load testing and/or return to
service.
WARNING:
• IF THE BATTERY SHOWS SIGNS OF FREEZ­
ING, LEAKING, LOOSE POSTS, OR LOW ELECTRO­
LYTE LEVEL, DO NOT TEST, ASSIST-BOOST, OR
CHARGE. THE BATTERY MAY ARC INTERNALLY
AND EXPLODE. PERSONAL INJURY AND/OR VEHI­
CLE DAMAGE MAY RESULT.
• EXPLOSIVE HYDROGEN GAS FORMS IN AND
AROUND THE BATTERY. DO NOT SMOKE, USE
FLAME, OR CREATE SPARKS NEAR THE BATTERY.
PERSONAL INJURY AND/OR VEHICLE DAMAGE
MAY RESULT.
• THE BATTERY CONTAINS SULFURIC ACID,
WHICH IS POISONOUS AND CAUSTIC. AVOID CON­
TACT WITH THE SKIN, EYES, OR CLOTHING. IN
THE EVENT OF CONTACT, FLUSH WITH WATER
AND CALL A PHYSICIAN IMMEDIATELY. KEEP OUT
OF THE REACH OF CHILDREN.
• IF THE BATTERY IS EQUIPPED WITH REMOV­
ABLE CELL CAPS, BE CERTAIN THAT EACH OF
THE CELL CAPS IS IN PLACE AND TIGHT BEFORE
THE BATTERY IS RETURNED TO SERVICE. PER­
SONAL INJURY AND/OR VEHICLE DAMAGE MAY
RESULT FROM LOOSE OR MISSING CELL CAPS,
Before testing, visually inspect the battery for any
damage (a cracked case or cover, loose posts, etc.)
that would cause the battery to be faulty. Then
remove the cell caps and check the electrolyte level.
Add distilled water i f the electrolyte level is below
the top of the battery plates.
Refer to the hydrometer manufacturer's instruc­
tions for correct use of the hydrometer. Remove only
enough electrolyte from the battery so that the float
is off the bottom of the hydrometer barrel with pres­
sure on the bulb released.
CAUTION: Exercise care when inserting the tip of
the hydrometer into a cell to avoid damaging the
plate separators. Damaged plate separators can
cause early battery failure.
To read the hydrometer correctly, hold i t with the
top surface of the electrolyte at eye level. Hydrometer
floats are generally calibrated to indicate the specific
gravity correctly only at 26.7°C (80°F). When testing
the specific gravity at any other temperature, a cor­
rection factor is required.
The correction factor is approximately a specific
gravity value of 0.004, referred to as 4 points of spe­
cific gravity. For each 5.5°C above 26.7°C (10°F above
80°F), add 4 points. For each 5.5°C below 26.7°C
(10°F below 80°F), subtract 4 points. Always correct
the specific gravity for temperature variation. Test
the specific gravity of the electrolyte in each battery
cell.
EXAMPLE: A battery is tested at -12.2°C (10°F)
and has a specific gravity of 1.240. Determine the
actual specific gravity as follows:
(1) Determine the number of degrees above or
below 26.7°C (80°F):
2 6 . 6 ° C - - 1 2 . 2 ° C = 3 8 . 8 ° C ( 8 0 ° F - 1 0 ° F =
7 0 ° F )
(2) Divide the result from Step 1 b y 5.5 (10):
3 8 . 8 ° C / 5 . 5 = 7 ( 7 0 ° F / 1 0 = 7 )
(3) Multiply the result from Step 2 by the temper­
ature correction factor (0.004):
7 X 0 . 0 0 4 = 0 . 0 2 8
(4) The temperature at testing was below 26.7°C
(80°F); therefore, the temperature correction factor is
subtracted:
1 . 2 4 0 - 0 . 0 2 8 = 1 . 2 1 2
The corrected specific gravity of the battery in this
example is 1.212.
I f the specific gravity of all cells is above 1.235, but
the variation between cells is more than 50 points
(0.050), the battery should be replaced. I f the specific
gravity of one or more cells is less than 1.235, charge
the battery at a rate of approximately 5 amperes.
Continue charging until three consecutive specific
gravity tests, taken at 1-hour intervals, are constant.
If the cell specific gravity variation is more than 50
points (0.050) at the end of the charge period, replace
the battery.
When the specific gravity of all cells is above 1.235,
and the cell variation is less than 50 points (0.050),