Diagnosis And Testing Battery - Jeep Cherokee XJ 1999 Manual

XJ
DESCRIPTION AND OPERATION (Continued)
COLD CRANKING AMPERAGE
The Cold Cranking Amperage (CCA) rating specifies
how much current (in amperes) the battery can 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
identified as the twenty-hour discharge rating.
MOUNTING
The battery is mounted in a molded plastic tray
located in the right front corner of the engine compart-
ment. Two T-bolts are held in formations on each side of
the tray by push-on retainers, and extend upward on
each side of the battery. A hold down strap fits across
the top of the battery case. The ends of the T-bolts pass
through the hold down strap on each side of the battery,
and a nut secures the hold down strap to the T-bolts.
One end of a support strap is located under the forward-
most hold down strap nut, and the other end is secured
to the upper radiator crossmember by a bolt.
A plastic bubble-wrap style thermoguard slides
over the battery case to enclose the sides of the bat-
tery. The thermoguard protects the battery from
engine compartment temperature extremes.
The battery tray is secured with three nuts to
three studs that protrude from the wheelhouse inner
panel, forward of the right front wheel.
A hole in the bottom of the battery tray is fitted
with a battery temperature sensor. Refer to Battery
Temperature Sensor in the Description and Opera-
tion section of Group 8C - Charging System for more
information on this component.
When installing a battery, be certain that the hold
down fasteners are tightened to the proper specifica-
tions. Improper hold
whether too loose or too tight, can result in damage
to the battery. Refer to Battery in the Removal and
Installation section of this group for the correct bat-
tery hold down fastener tightness specifications.
DIAGNOSIS AND TESTING
BATTERY
DIAGNOSIS
The battery, starting, and charging systems oper-
ate with one another, and must be tested as a com-
plete system. In order for the vehicle to start and
charge properly, all of the components involved in
these systems must perform within specifications.
Group 8A covers the Battery, Group 8B covers the
Starting Systems, and Group 8C covers the Charging
System. We have separated these systems to make it
easier to locate the information you are seeking
within this Service Manual. However, when attempt-
ing to diagnose any of these systems, it is important
that you keep their interdependency in mind.
The diagnostic procedures used in these groups
include the most basic conventional diagnostic meth-
ods, to the more sophisticated On-Board Diagnostics
(OBD) built into the Powertrain Control Module
(PCM). Use of an induction-type milliampere amme-
ter, volt/ohmmeter, battery charger, carbon pile rheo-
stat (load tester), and 12-volt test lamp may be
required.
All OBD-sensed systems are monitored by the
PCM. Each monitored circuit is assigned a Diagnos-
tic Trouble Code (DTC). The PCM will store a DTC in
electronic memory for any failure it detects. Refer to
On-Board Diagnostic Test For Charging System
in the Diagnosis and Testing section of Group 8C -
Charging System for more information.
The battery must be completely charged and the
top, posts, and terminal clamps should be properly
cleaned and inspected before diagnostic procedures
are performed. Refer to Battery in the Removal and
Installation section of this group for the proper bat-
tery cleaning and inspection procedures. Refer to
Battery Charging in the Service Procedures section
of this group for the proper charging procedures.
BATTERY 8A - 3
down fastener tightness,