Dodge ram truck 3500 1996 Service Manual page 356

8A - 8 BATTERY
DIAGNOSIS mm T E S T I N G ( C o n t i n u e d l
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.
Before proceeding with this test, completely charge
the battery as described in Battery Charging i n this
group.
NOTE: Models equipped with the diesel engine
option are equipped with two 12-volt batteries, con­
nected in parallel (positive-to-positive/negative-to-
negative). The secondary battery, on the
passenger's side, is dedicated to providing current
for the operation of the intake manifold air heater.
The primary battery, on the driver's side, is dedi­
cated to all other vehicle electrical requirements. In
order to ensure accurate diagnostic results, these
batteries MUST be disconnected from each other,
as well as from the vehicle electrical system, when
being tested.
(1) Disconnect and isolate both battery cables, neg­
ative cable first. The battery top and posts should be
clean.
(2) Connect a suitable volt-ammeter-load tester
(Fig. 5) to the battery posts (Fig. 6). Refer to the
operating instructions provided with the tester being
used. Check the open-circuit voltage (no load) of the
battery. Open-circuit voltage must be 12.4 volts or
greater.
(3) Rotate the load control knob (carbon pile rheo­
stat) to apply a 300 amp load to the battery for 15
seconds, then return the control knob to the Off posi­
tion (Fig. 7). This will remove the surface charge
from the battery.
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Fig. 5 Volt-Ammeter-Load Tester - Typical
J948A-13
Fig. 6 Volt-Ammeier-Load Tester Connections
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Fig. 7 Remove Surface Charge from Battery
(4) Allow the battery to stabilize to open-circuit
voltage. I t may take up to five minutes for the bat­
tery voltage to stabilize.
(5) Rotate the load control knob to maintain a load
equal to 50% of the battery's CCA rating (Fig. 8).
After 15 seconds, record the loaded voltage reading,
then return the load control knob to the Off position.