Jeep Cherokee XJ 1999 Manual - page 14
CAUTION:
•
Always disconnect and isolate the battery neg-
ative cable before charging a battery. Do not exceed
sixteen volts while charging a battery. Damage to
the vehicle electrical system components may
result.
•
Battery electrolyte will bubble inside the bat-
tery case during normal battery charging. Electro-
lyte boiling or being discharged from the battery
vents indicates a battery overcharging condition.
Immediately reduce the charging rate or turn off the
charger to evaluate the battery condition. Damage
to the battery may result from overcharging.
•
The battery should not be hot to the touch. If
the battery feels hot to the touch, turn off the
charger and let the battery cool before continuing
the charging operation. Damage to the battery may
result.
Some battery chargers are equipped with polarity-
sensing circuitry. This circuitry protects the charger
and/or the battery from being damaged if they are
improperly connected. If the battery state-of-charge
is too low for the polarity-sensing circuitry to detect,
the charger will not operate. This makes it appear
that the battery will not accept charging current. See
the instructions provided by the manufacturer of the
battery charger for details on how to bypass the
polarity-sensing circuitry.
After the battery has been charged to 12.4 volts or
greater, perform a load test to determine the battery
cranking capacity. Refer to Load Test in the Diagno-
sis and Testing section of this group for the proce-
dures. If the battery will endure a load test, return
the battery to use. If the battery will not endure a
load test, it is faulty and must be replaced.
Clean and inspect the battery hold downs, tray,
terminals, posts, and top before completing service.
Refer to Battery in the Removal and Installation
section of this group for the proper cleaning and
inspection procedures.
CHARGING A COMPLETELY DISCHARGED
BATTERY
The following procedure should be used to recharge
a completely discharged battery. Unless this proce-
dure is properly followed, a good battery may be
needlessly replaced.
(1) Measure the voltage at the battery posts with a
voltmeter, accurate to 1/10 (0.10) volt (Fig. 14). If the
reading is below ten volts, the charge current will be
low. It could take some time before the battery
accepts a current greater than a few milliamperes.
Such low current may not be detectable on the
ammeters built into many battery chargers.
(2) Disconnect and isolate the battery negative
cable. Connect the battery charger leads. Some bat-
tery chargers are equipped with polarity-sensing cir-
cuitry. This circuitry protects the charger and/or the
battery from being damaged if they are improperly
connected. If the battery state-of-charge is too low for
the polarity-sensing circuitry to detect, the charger
will not operate. This makes it appear that the bat-
tery will not accept charging current. See the instruc-
tions provided by the manufacturer of the battery
charger for details on how to bypass the polarity-
sensing circuitry.
(3) Battery chargers vary in the amount of voltage
and current they provide. The amount of time
required for a battery to accept measurable charger
current at various voltages is shown in the Charge
Rate chart. If the charge current is still not measur-
able at the end of the charging time, the battery is
faulty and must be replaced. If the charge current is
measurable during the charging time, the battery
may be good and the charging should be completed in
the normal manner.
CHARGING TIME REQUIRED
The time required to charge a battery will vary,
depending upon the following factors:
•
Battery Capacity - A completely discharged
heavy-duty battery requires twice the charging time
of a small capacity battery.
•
Temperature - A longer time will be needed to
charge a battery at -18° C (0° F) than at 27° C (80°
F). When a fast charger is connected to a cold bat-
Fig. 14 Voltmeter Accurate to 1/10 Volt Connected -
Typical
Charge Rate
Voltage
Hours
16.0 volts maximum
up to 4 hours
14.0 to 15.9 volts
up to 8 hours
13.9 volts or less
up to 16 hours
8A - 14
BATTERY
XJ
SERVICE PROCEDURES (Continued)