Diagnosis And Testing; Battery - Jeep 1997 Grand Cherokee Service Manual

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DESCRIPTION AND OPERATION (Continued)
deliver for thirty seconds at -18° C (0° F). Terminal
voltage must not fall below 7.2 volts during or after
the thirty second discharge period. The CCA required
is generally higher as engine displacement increases,
depending also upon the starter current draw
requirements.
RESERVE CAPACITY
The Reserve Capacity (RC) rating specifies the
time (in minutes) it takes for battery terminal volt-
age to fall below 10.5 volts, at a discharge rate of 25
amperes. RC is determined with the battery fully-
charged at 26.7° C (80° F). This rating estimates how
long the battery might last after a charging system
failure, under minimum electrical load.
AMPERE-HOURS
The Ampere-Hours (AH) rating specifies the cur-
rent (in amperes) that a battery can deliver steadily
for twenty hours, with the voltage in the battery not
falling below 10.5 volts. This rating is also sometimes
referred to as the twenty-hour discharge rating.
BATTERY MOUNTING
The battery is mounted to a molded plastic tray
located in the right front corner of the engine com-
partment. A U-nut is held in a formation on each side
of the battery tray. A holddown strap fits across the
top of the battery case and thermoguard. To secure
the battery in the tray, a bolt passes through the
holddown strap on each side of the battery, and is
threaded into the U-nut on each side of the battery
tray.
The battery tray is secured with three screws to
the front wheelhouse extension panel, forward of the
right front wheel. The tray is also secured to the
right fender inner shield with two screws.
A vacuum reservoir for the vehicle speed control
and heater-A/C systems is mounted to the underside
of the battery tray. Refer to Group 8H - Vehicle
Speed Control System or Group 24 - Heating and Air
Conditioning for more information on the vacuum
reservoir.
On some models, a hole in the bottom of the bat-
tery tray is fitted with a battery temperature sensor.
Models without the battery temperature sensor have
a plug fitted to this hole. Refer to Group 8C - Charg-
ing System for more information on the battery tem-
perature sensor.
When installing a battery, be certain that the hold-
down fasteners are tightened to the proper specifica-
tions. Improper holddown fastener tightness, whether
too loose or too tight, can result in damage to the
battery. See the Battery Removal and Installation
procedures for the correct holddown fastener tight-
ness specifications.

DIAGNOSIS AND TESTING

BATTERY

The battery must be completely charged and the
top, posts, and terminal clamps should be properly
cleaned before diagnostic procedures are performed.
See the Battery Charging procedure in this group for
more information.
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.
The condition of a battery is determined by two cri-
teria:
1. State-Of-Charge - This can be determined by
viewing the built-in test indicator, by checking the
specific gravity of the electrolyte (hydrometer test),
or by checking the battery voltage (open-circuit volt-
age test).
2. Cranking Capacity - This can be determined
by performing a battery load test, which measures
the ability of the battery to supply high-amperage
current.
First, determine the battery state-of-charge. This
can be done in one of three ways. If the battery has a
built-in test indicator, view the test indicator to
determine the state-of-charge. If the battery has no
test indicator, but has removable cell caps, perform
the hydrometer test to determine the state-of-charge.
If the cell caps are not removable, or a hydrometer is
not available, perform the open-circuit voltage test to
determine the state-of-charge.
The battery must be charged before proceeding
with a load test if:
BATTERY 8A - 3