Jeep 1997 Grand Cherokee Service Manual page 313

ZG
SERVICE PROCEDURES (Continued)
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.
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.
Refer to the instructions provided with the battery
charger 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. 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 holddowns, tray, ter-
minals, posts, and top before completing service. See
the Battery Removal and Installation procedures in
this group for more information.
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. 15). 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 chargers.
Fig. 15 Voltmeter Accurate to 1/10 Volt Connected-
(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. Refer to the
instructions provided with the battery charger 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
BATTERY
Typical
8A - 13