Dodge 2000 DURANGO Service Manual page 256

8A - 10 BATTERY
DIAGNOSIS AND TESTING (Continued)
Fig. 6 Built-In Test Indicator Sight Glass
Specific gravity is a comparison of the density of
the battery electrolyte to the density of pure water.
Pure water has a specific gravity of 1.000, and sulfu-
ric acid has a specific gravity of 1.835. Sulfuric acid
makes up approximately 35% of the battery electro-
lyte by weight, or 24% by volume. In a fully-charged
battery the electrolyte will have a temperature-cor-
rected 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 battery cell caps and check the electrolyte
level. Add distilled water if the electrolyte level is
below the top of the battery plates.
See the instructions provided by the manufacturer
of the hydrometer for recommendations on the cor-
rect use of the hydrometer that you are using.
Remove only enough electrolyte from the battery cell
so that the float is off the bottom of the hydrometer
barrel with pressure on the bulb released. To read
the hydrometer correctly, hold it with the top surface
of the electrolyte at eye level (Fig. 7).
CAUTION: Exercise care when inserting the tip of
the hydrometer into a battery cell to avoid damag-
ing the plate separators. Damaged plate separators
can cause early battery failure.
Fig. 7 Hydrometer - Typical
1 – BULB
2 – SURFACE COHESION
3 – SPECIFIC GRAVITY READING
4 – TEMPERATURE READING
5 – HYDROMETER BARREL
6 – FLOAT
Hydrometer floats are generally calibrated to indi-
cate the specific gravity correctly only at 26.7° C (80°
F). When testing the specific gravity at any other
temperature, a correction factor is required. The cor-
rection factor is approximately a specific gravity
value of 0.004, which may also be identified as four
points of specific gravity. For each 5.5° C above 26.7°
C (10° F above 80° F), add four points. For each 5.5°
C below 26.7° C (10° F below 80° F), subtract four
points. Always correct the specific gravity for temper-
ature variation.
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:
DN