Built-In Test Indicator; Hydrometer Test - Jeep 1997 Grand Cherokee Service Manual

SIGHT PLASTIC ROD GLASS GREEN BALL
8A - 6 BATTERY
DIAGNOSIS AND TESTING (Continued)
ABNORMAL BATTERY DISCHARGING
Any of the following conditions can result in abnor-
mal battery discharging:
1. Corroded or loose battery posts and terminal
clamps.
2. A loose or worn generator drive belt.
3. Electrical loads that exceed the output of the
charging system. This can be due to equipment
installed after manufacture, or repeated short trip
use.
4. Slow driving speeds (heavy traffic conditions) or
prolonged idling, with high-amperage draw systems
in use.
5. A faulty circuit or component causing excessive
ignition-off draw. See the Ignition-Off Draw Test pro-
cedure in this group for more information.
6. A faulty or incorrect charging system compo-
nent. Refer to Group 8C - Charging System for more
information.
7. A faulty or incorrect battery.

BUILT-IN TEST INDICATOR

A test indicator (hydrometer) built into the top of
the battery case provides visual information for bat-
tery testing (Fig. 2). Like a hydrometer, the built-in
test indicator measures the specific gravity of the
electrolyte. The test indicator reveals the battery
state-of-charge; however, it will not reveal the crank-
ing capacity of the battery. A load test must be per-
formed to determine the battery cranking capacity.
See the Load Test procedure in this group for more
information.
Fig. 2 Built-In Test Indicator
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.
BATTERY TOP
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. In order to
obtain correct indications from the built-in test indi-
cator, it is important that the battery be level and
have a clean sight glass. Additional light may be
required to view the indicator. Do not use open
flame as a source of additional light.
To read the built-in test indicator, look into the
sight glass and note the color of the indicator (Fig. 3).
Refer to the following description, as the color indi-
cates:
• Green - indicates 75% to 100% state-of-charge.
The battery is adequately charged for further testing
or return to use. If the vehicle will not crank for a
minimum of fifteen seconds with a fully-charged bat-
tery, perform the Load Test procedure as described in
this group.
• Black or Dark - indicates 0% to 75% state-of-
charge. The battery is inadequately charged and
must be charged until a green indication is visible in
the sight glass (12.4 volts or more), before the bat-
tery is tested further or returned to service. See the
Battery Charging procedure in this group for more
information. Also see Abnormal Battery Discharging
in this group for possible causes of the discharged
condition.
•
Clear or Bright - indicates a low electrolyte
level. The electrolyte level in the battery is below the
test indicator. A maintenance-free battery with non-
removable cell caps must be replaced if the electro-
lyte level is low. Water must be added to a low-
maintenance battery with removable cell caps before
it is charged. See the Battery Charging procedure in
this group for more information. A low electrolyte
level may be caused by an overcharging condition.
Refer to Group 8C - Charging System to diagnose an
overcharging condition.

HYDROMETER TEST

The hydrometer test reveals the battery state-of-
charge by measuring the specific gravity of the elec-
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