DODGE RAM 2002 Service Repair Manual

²Battery- The storage battery provides a reli-
able means of storing a renewable source of electrical
energy within the vehicle.
²Battery Cable- The battery cables connect the
battery terminal posts to the vehicle electrical sys-
tem.
²Battery Holddown- The battery holddown
hardware secures the battery in the battery tray in
the engine compartment.
²Battery Tray- The battery tray provides a
secure mounting location in the vehicle for the bat-
tery and an anchor point for the battery holddown
hardware.
For battery system maintenance schedules and
jump starting procedures, see the owner's manual in
the vehicle glove box. Optionally, refer to Lubrication
and Maintenance for the recommended battery main-
tenance schedules and for the proper battery jump
starting procedures. While battery charging can be
considered a maintenance procedure, the battery
charging procedures and related information are
located in the standard procedures section of this ser-
vice manual. This was done because the battery must
be fully-charged before any battery system diagnosis
or testing procedures can be performed. Refer to
Standard procedures for the proper battery charging
procedures.
OPERATION
The battery system is designed to provide a safe,
efficient, reliable and mobile means of delivering and
storing electrical energy. This electrical energy is
required to operate the engine starting system, as
well as to operate many of the other vehicle acces-
sory systems for limited durations while the engine
and/or the charging system are not operating. The
battery system is also designed to provide a reserve
of electrical energy to supplement the charging sys-
tem for short durations while the engine is running
and the electrical current demands of the vehicle
exceed the output of the charging system. In addition
to delivering, and storing electrical energy for the
vehicle, the battery system serves as a capacitor and
voltage stabilizer for the vehicle electrical system. It
absorbs most abnormal or transient voltages caused
by the switching of any of the electrical components
or circuits in the vehicle.
DIAGNOSIS AND TESTING - BATTERY SYSTEM
The battery, starting, and charging systems in the
vehicle operate with one another and must be tested
as a complete system. In order for the engine to start
and the battery to maintain its charge properly, all of
the components that are used in these systems must
perform within specifications. It is important that
the battery, starting, and charging systems be thor-
oughly tested and inspected any time a battery needs
to be charged or replaced. The cause of abnormal bat-
tery discharge, overcharging or early battery failure
must be diagnosed and corrected before a battery is
replaced and before a vehicle is returned to service.
The service information for these systems has been
separated within this service manual to make it eas-
ier to locate the specific information you are seeking.
However, when attempting to diagnose any of these
systems, it is important that you keep their interde-
pendency in mind.
The diagnostic procedures used for the battery,
starting, and charging systems include the most
basic conventional diagnostic methods, to the more
sophisticated On-Board Diagnostics (OBD) built into
the Powertrain Control Module (PCM). Use of an
induction-type milliampere ammeter, a volt/ohmme-
ter, a battery charger, a carbon pile rheostat (load
tester) and a 12-volt test lamp may be required. All
OBD-sensed systems are monitored by the PCM.
Each monitored circuit is assigned a Diagnostic Trou-
ble Code (DTC). The PCM will store a DTC in elec-
tronic memory for any failure it detects. Refer to
Charging System for the proper charging system on-
board diagnostic test procedures.
MIDTRONICS ELECTRICAL SYSTEM TESTER
The Midtronicstautomotive battery and charging
system tester is designed to help the dealership tech-
nicians diagnose the cause of a defective battery or
charging system. Follow the instruction manual sup-
plied with the tester to properly diagnose a vehicle. If
the instruction manual is not available refer to the
standard procedure in this section, which includes
the directions for using the midtronics electrical sys-
tem tester.
8F - 2 BATTERY SYSTEMBR/BE
BATTERY SYSTEM (Continued)

BATTERY SYSTEM DIAGNOSIS
CONDITION POSSIBLE CAUSES CORRECTION
THE BATTERY SEEMS
WEAK OR DEAD WHEN
ATTEMPTING TO START
THE ENGINE.1. The electrical system
ignition-off draw is excessive.1. Refer to the IGNITION-OFF DRAW TEST
Standard Procedure for the proper test
procedures. Repair the excessive ignition-off
draw, as required.
2. The charging system is
faulty.2. Determine if the charging system is performing
to specifications using the Midtronics battery and
charging system tester. Refer to Charging System
for additional charging system diagnosis and
testing procedures. Repair the faulty charging
system, as required.
3. The battery is discharged. 3. Determine the battery state-of-charge using the
Midtronics battery and charging system tester.
Refer to the Standard Procedures in this section
for additional test procedures. Charge the faulty
battery, as required.
4. The battery terminal
connections are loose or
corroded.4. Refer to Battery Cables for the proper battery
cable diagnosis and testing procedures. Clean
and tighten the battery terminal connections, as
required.
5. The battery has an
incorrect size or rating for
this vehicle.5. Refer to Battery System Specifications for the
proper size and rating. Replace an incorrect
battery, as required.
6. The battery is faulty. 6. Determine the battery cranking capacity using
the Midtronics battery and charging system tester.
Refer to the Standard Procedures in this section
for additional test procedures. Replace the faulty
battery, as required.
7. The starting system is
faulty.7. Determine if the starting system is performing
to specifications. Refer to Starting System for the
proper starting system diagnosis and testing
procedures. Repair the faulty starting system, as
required.
8. The battery is physically
damaged.8. Inspect the battery for loose terminal posts or a
cracked and leaking case. Replace the damaged
battery, as required.
BR/BEBATTERY SYSTEM 8F - 3
BATTERY SYSTEM (Continued)

BATTERY SYSTEM DIAGNOSIS
CONDITION POSSIBLE CAUSES CORRECTION
THE BATTERY STATE OF
CHARGE CANNOT BE
MAINTAINED.1. The battery has an
incorrect size or rating for
this vehicle.1. Refer to Battery System Specifications for the
proper specifications. Replace an incorrect
battery, as required.
2. The battery terminal
connections are loose or
corroded.2. Refer to Battery Cable for the proper cable
diagnosis and testing procedures. Clean and
tighten the battery terminal connections, as
required.
3. The electrical system
ignition-off draw is excessive.3. Refer to the IGNITION-OFF DRAW TEST
Standard Procedure for the proper test
procedures. Repair the faulty electrical system, as
required.
4. The battery is faulty. 4. Test the battery using the Midtronics battery
and charging system tester. Refer to Standard
Procedures for additional test procedures.
Replace the faulty battery, as required.
5. The starting system is
faulty.5. Determine if the starting system is performing
to specifications. Refer to Starting System for the
proper starting system diagnosis and testing
procedures. Repair the faulty starting system, as
required.
6. The charging system is
faulty.6. Determine if the charging system is performing
to specifications using the Midtronics battery and
charging system tester.. Refer to Charging
System for additional charging system diagnosis
and testing procedures. Repair the faulty charging
system, as required.
7. Electrical loads exceed the
output of the charging
system.7. Inspect the vehicle for aftermarket electrical
equipment which might cause excessive electrical
loads.
8. Slow driving or prolonged
idling with high-amperage
draw systems in use.8. Advise the vehicle operator, as required.
THE BATTERY WILL NOT
ACCEPT A CHARGE.1. The battery is faulty. 1. Test the battery using the Midtronics battery
and charging system tester.. Charge or replace
the faulty battery, as required.
8F - 4 BATTERY SYSTEMBR/BE
BATTERY SYSTEM (Continued)

ABNORMAL BATTERY DISCHARGING
Any of the following conditions can result in abnor-
mal battery discharging:
²A faulty or incorrect charging system compo-
nent. Refer to Charging System for the proper charg-
ing system diagnosis and testing procedures.
²A faulty or incorrect battery. Refer to Standard
Procedures for the proper battery diagnosis and test-
ing procedures. Refer to Battery System Specifica-
tions for the proper specifications.
²A faulty circuit or component causing excessive
ignition-off draw.
²Electrical loads that exceed the output of the
charging system. This can be due to equipment
installed after manufacture, or repeated short trip
use.
²A faulty or incorrect starting system component.
Refer to Starting System for the proper starting sys-
tem diagnosis and testing procedures.
²Corroded or loose battery posts and terminal
clamps.
²A loose or worn generator drive belt.
²Slow driving speeds (heavy traffic conditions) or
prolonged idling, with high-amperage draw systems
in use.
CLEANING
The following information details the recommended
cleaning procedures for the battery and related com-
ponents. In addition to the maintenance schedules
found in this service manual and the owner's man-
ual, it is recommended that these procedures be per-
formed any time the battery or related components
must be removed for vehicle service.
(1) Clean the battery cable terminal clamps of all
corrosion. Remove any corrosion using a wire brush
or a post and terminal cleaning tool, and a sodium
bicarbonate (baking soda) and warm water cleaning
solution (Fig. 1).
(2) Clean the battery tray and battery holddown
hardware of all corrosion. Remove any corrosion
using a wire brush and a sodium bicarbonate (baking
soda) and warm water cleaning solution. Paint any
exposed bare metal.
(3) If the removed battery is to be reinstalled,
clean the outside of the battery case and the top
cover with a sodium bicarbonate (baking soda) and
warm water cleaning solution using a stiff bristle
parts cleaning brush to remove any acid film (Fig. 2).
Rinse the battery with clean water. Ensure that the
cleaning solution does not enter the battery cells
through the vent holes. If the battery is being
replaced, refer to Battery System Specifications for
the factory-installed battery specifications. Confirm
that the replacement battery is the correct size and
has the correct ratings for the vehicle.
Fig. 1 Clean Battery Cable Terminal Clamp - Typical
1 - TERMINAL BRUSH
2 - BATTERY CABLE
Fig. 2 Clean Battery - Typical
1 - CLEANING BRUSH
2 - WARM WATER AND BAKING SODA SOLUTION
3 - BATTERY
BR/BEBATTERY SYSTEM 8F - 5
BATTERY SYSTEM (Continued)

(4) Clean the battery thermal guard with a sodium
bicarbonate (baking soda) and warm water cleaning
solution using a stiff bristle parts cleaning brush to
remove any acid film.
(5) Clean any corrosion from the battery terminal
posts with a wire brush or a post and terminal
cleaner, and a sodium bicarbonate (baking soda) and
warm water cleaning solution (Fig. 3).
INSPECTION
The following information details the recommended
inspection procedures for the battery and related
components. In addition to the maintenance sched-
ules found in this service manual and the owner's
manual, it is recommended that these procedures be
performed any time the battery or related compo-
nents must be removed for vehicle service.
(1) Inspect the battery cable terminal clamps for
damage. Replace any battery cable that has a dam-
aged or deformed terminal clamp.
(2) Inspect the battery tray and battery holddown
hardware for damage. Replace any damaged parts.
(3) Slide the thermal guard off of the battery case,
if equipped. Inspect the battery case for cracks or
other damage that could result in electrolyte leaks.
Also, check the battery terminal posts for looseness.
Batteries with damaged cases or loose terminal posts
must be replaced.
(4) Inspect the battery thermal guard for tears,
cracks, deformation or other damage. Replace any
battery thermal guard that has been damaged.(5) Inspect the battery built-in test indicator sight
glass for an indication of the battery condition. If the
battery is discharged, charge as required. (Refer to 8
- ELECTRICAL/BATTERY SYSTEM/BATTERY -
STANDARD PROCEDURE).
SPECIFICATIONS
BATTERY
Battery Classifications and Ratings
Part NumberBCI Group Size
ClassificationCold
Cranking
AmperageReserve
CapacityAmpere-HoursLoad Test
Amperage
56028375AA 27 600 120 Minutes 66 300
56028376AA 27 750 150 Minutes 75 375
Fig. 3 Clean Battery Terminal Post - Typical
1 - TERMINAL BRUSH
2 - BATTERY CABLE
3 - BATTERY
8F - 6 BATTERY SYSTEMBR/BE
BATTERY SYSTEM (Continued)

SPECIAL TOOLS
BATTERY
DESCRIPTION
A large capacity, low-maintenance storage battery
(Fig. 4) is standard factory-installed equipment on
this model. Refer to Battery System Specifications for
the proper specifications of the factory-installed bat-
teries available on this model. Male post type termi-
nals made of a soft lead material protrude from the
top of the molded plastic battery case to provide the
means for connecting the battery to the vehicle elec-
trical system. The battery positive terminal post is
physically larger in diameter than the negative ter-
minal post to ensure proper battery connection. The
lettersPOSandNEGare also molded into the top of
the battery case adjacent to their respective positive
and negative terminal posts for identification confir-
mation. Refer to Battery Cables for more information
on the battery cables that connect the battery to the
vehicle electrical system.
The battery is made up of six individual cells that
are connected in series. Each cell contains positively
charged plate groups that are connected with lead
straps to the positive terminal post, and negatively
charged plate groups that are connected with lead
straps to the negative terminal post. Each plate con-
sists of a stiff mesh framework or grid coated with
lead dioxide (positive plate) or sponge lead (negative
plate). Insulators or plate separators made of a non-
conductive material are inserted between the positiveand negative plates to prevent them from contacting
or shorting against one another. These dissimilar
metal plates are submerged in a sulfuric acid and
water solution called an electrolyte.
The factory-installed battery has a built-in test
indicator (hydrometer). The color visible in the sight
glass of the indicator will reveal the battery condi-
tion. Refer to Standard Procedures for the proper
built-in indicator test procedures.The factory-in-
stalled low-maintenance battery has non-re-
movable battery cell caps.Water cannot be added
to this battery. The battery is not sealed and has
vent holes in the cell caps. The chemical composition
of the metal coated plates within the low-mainte-
nance battery reduces battery gassing and water
loss, at normal charge and discharge rates. There-
fore, the battery should not require additional water
in normal service. Rapid loss of electrolyte can be
caused by an overcharging condition. Be certain to
diagnose the charging system before returning the
vehicle to service. (Refer to 8 - ELECTRICAL/
CHARGING - DIAGNOSIS AND TESTING).
DIAGNOSIS AND TESTING - BATTERY
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 System Cleaning for
MIDTRONICS BATTERY AND CHARGING SYSTEM
TESTER - Micro420
Fig. 4 Low-Maintenance Battery - Typical
1 - POSITIVE POST
2 - VENT
3 - CELL CAP
4 - TEST INDICATOR
5 - CELL CAP
6 - VENT
7 - NEGATIVE POST
8 - GREEN BALL
9 - ELECTROLYTE LEVEL
10 - PLATE GROUPS
11 - LOW-MAINTENANCE BATTERY
BR/BEBATTERY SYSTEM 8F - 7
BATTERY SYSTEM (Continued)

the proper cleaning procedures, and Battery System
Inspection for the proper battery inspection proce-
dures. Refer to Standard Procedures for the proper
battery charging procedures.
WARNING: IF THE BATTERY SHOWS SIGNS OF
FREEZING, LEAKING OR LOOSE POSTS, DO NOT
TEST, ASSIST-BOOST, OR CHARGE. THE BATTERY
MAY ARC INTERNALLY AND EXPLODE. PERSONAL
INJURY AND/OR VEHICLE DAMAGE MAY RESULT.
WARNING: EXPLOSIVE HYDROGEN GAS FORMS IN
AND AROUND THE BATTERY. DO NOT SMOKE,
USE FLAME, OR CREATE SPARKS NEAR THE BAT-
TERY. PERSONAL INJURY AND/OR VEHICLE DAM-
AGE MAY RESULT.
WARNING: THE BATTERY CONTAINS SULFURIC
ACID, WHICH IS POISONOUS AND CAUSTIC. AVOID
CONTACT 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.
The condition of a battery is determined by two cri-
teria:
²State-Of-Charge- This can be determined by
checking the specific gravity of the battery electrolyte
(built-in indicator test or hydrometer test), or by
checking the battery voltage (open-circuit voltage
test).
²Cranking 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, perform the built-in indicator
test to determine the state-of-charge. If the battery
has no built-in test indicator but does have remov-
able cell caps, perform the hydrometer test to deter-
mine the state-of-charge. If the battery cell caps are
not removable, or a hydrometer is not available, per-
form the open-circuit voltage test to determine the
state-of-charge. Refer to open-circuit voltage test in
the Standard Procedures section of this group.
Second, determine the battery cranking capacity by
performing a load test. The battery must be charged
before proceeding with a load test if:
²The battery built-in test indicator has a black or
dark color visible.
²The temperature corrected specific gravity of the
battery electrolyte is less than 1.235.
²The battery open-circuit voltage is less than 12.4
volts.A battery that will not accept a charge is faulty,
and must be replaced. Further testing is not
required. A fully-charged battery must be load tested
to determine its cranking capacity. A battery that is
fully-charged, but does not pass the load test, is
faulty and must be replaced.
NOTE: Completely discharged batteries may take
several hours to accept a charge. Refer to Standard
Procedures for the proper battery charging proce-
dures.
A battery is fully-charged when:
²All battery cells are gassing freely during charg-
ing.
²A green color is visible in the sight glass of the
battery built-in test indicator.
²Three corrected specific gravity tests, taken at
one-hour intervals, indicate no increase in the spe-
cific gravity of the battery electrolyte.
²Open-circuit voltage of the battery is 12.4 volts
or greater.
STANDARD PROCEDURE
STANDARD PROCEDURE - BATTERY
CHARGING
Battery charging can be performed fast or slow, it
terms of time.Slowbattery charging is the best
means of restoring a battery to full potential. Fast
battery charging should only be performed when
absolutely necessary due to time restraints. A battery
is fully-charged when:
²All of the battery cells are gassing freely during
battery charging.
²A green color is visible in the sight glass of the
battery built-in test indicator.
²Three hydrometer tests, taken at one-hour inter-
vals, indicate no increase in the temperature-cor-
rected specific gravity of the battery electrolyte.
²Open-circuit voltage of the battery is 12.65 volts
or above.
WARNING: NEVER EXCEED TWENTY AMPERES
WHEN CHARGING A COLD (-1É C [30É F] OR
LOWER) BATTERY. THE BATTERY MAY ARC INTER-
NALLY AND EXPLODE. PERSONAL INJURY AND/OR
VEHICLE DAMAGE MAY RESULT.
CAUTION: Always disconnect and isolate the bat-
tery negative cable before charging a battery. Do
not exceed sixteen volts while charging a battery.
Damage to the vehicle electrical system compo-
nents may result.
8F - 8 BATTERY SYSTEMBR/BE
BATTERY (Continued)

CAUTION: Battery electrolyte will bubble inside the
battery case during normal battery charging. Elec-
trolyte 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.
CAUTION: 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 continu-
ing the charging operation. Damage to the battery
may result.
NOTE: Models equipped with the diesel engine
option are equipped with two 12-volt batteries, con-
nected in parallel (positive-to-positive and negative-
to-negative). In order to ensure proper charging of
each battery, these batteries MUST be disconnected
from each other, as well as from the vehicle electri-
cal system, while being charged.
Some battery chargers are equipped with polarity-
sensing circuitry. This circuitry protects the battery
charger and 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 battery 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 Standard Procedures for
the proper battery load test procedures. If the battery
will endure a load test, return the battery to service.
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 battery
service. Refer to Battery System Cleaning for the
proper battery system cleaning procedures, and Bat-
tery System Inspection for the proper battery system
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. 5). If the
reading is below ten volts, the battery charging cur-rent will be low. It could take some time before the
battery accepts a current greater than a few milliam-
peres. 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 battery charger and
the battery from being damaged if they are improp-
erly connected. If the battery state-of-charge is too
low for the polarity-sensing circuitry to detect, the
battery charger will not operate. This makes it
appear that the battery will not accept charging cur-
rent. See the instructions provided by the manufac-
turer 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 charging
current at various voltages is shown in the Charge
Rate Table. If the charging current is still not mea-
surable at the end of the charging time, the battery
is faulty and must be replaced. If the charging cur-
rent is measurable during the charging time, the bat-
tery may be good and the charging should be
completed in the normal manner.
CHARGE RATE TABLE
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
CHARGING TIME REQUIRED
The time required to charge a battery will vary,
depending upon the following factors:
²Battery Capacity- A completely discharged
heavy-duty battery requires twice the charging time
of a small capacity battery.
Fig. 5 Voltmeter - Typical
BR/BEBATTERY SYSTEM 8F - 9
BATTERY (Continued)

²Temperature- A longer time will be needed to
charge a battery at -18É C (0É F) than at 27É C (80É
F). When a fast battery charger is connected to a cold
battery, the current accepted by the battery will be
very low at first. As the battery warms, it will accept
a higher charging current rate (amperage).
²Charger Capacity- A battery charger that
supplies only five amperes will require a longer
charging time. A battery charger that supplies
twenty amperes or more will require a shorter charg-
ing time.
²State-Of-Charge- A completely discharged bat-
tery requires more charging time than a partially
discharged battery. Electrolyte is nearly pure water
in a completely discharged battery. At first, the
charging current (amperage) will be low. As the bat-
tery charges, the specific gravity of the electrolyte
will gradually rise.
The Battery Charging Time Table gives an indica-
tion of the time required to charge a typical battery
at room temperature based upon the battery state-of-
charge and the charger capacity.
BATTERY CHARGING TIME TABLE
Charging
Amperage5 Amps10
Amps20 Amps
Open Circuit
VoltageHours Charging @
21É C (70É F)
12.25 to 12.49 6 hours 3 hours 1.5
hours
12.00 to 12.24 10 hours 5 hours 2.5
hours
10.00 to 11.99 14 hours 7 hours 3.5
hours
Below 10.00 18 hours 9 hours 4.5
hours
STANDARD PROCEDURE - BUILT-IN
INDICATOR TEST
An indicator (hydrometer) built into the top of the
battery case provides visual information for battery
testing (Fig. 6). Like a hydrometer, the built-in indi-
cator measures the specific gravity of the battery
electrolyte. The specific gravity of the electrolyte
reveals the battery state-of-charge; however, it will
not reveal the cranking capacity of the battery. A load
test must be performed to determine the battery
cranking capacity. Refer to Standard Procedures for
the proper battery load test procedures.
Before testing, visually inspect the battery for any
damage (a cracked case or cover, loose posts, etc.)
that would cause the battery to be faulty. In order to
obtain correct indications from the built-in indicator,
it is important that the battery be level and have aclean sight glass. Additional light may be required to
view the indicator.Do not use open flame as a
source of additional light.
To read the built-in indicator, look into the sight
glass and note the color of the indication (Fig. 7). The
battery condition that each color indicates is
described in the following list:
²Green- Indicates 75% to 100% battery state-of-
charge. The battery is adequately charged for further
testing or return to service. If the starter will not
crank for a minimum of fifteen seconds with a fully-
charged battery, the battery must be load tested.
Refer to Standard Procedures for the proper battery
load test procedures.
²Black or Dark- Indicates 0% to 75% battery
state-of-charge. The battery is inadequately charged
and must be charged until a green indication is visi-
ble in the sight glass (12.4 volts or more), before the
battery is tested further or returned to service. Refer
to Standard Procedures for the proper battery charg-
ing procedures. Also refer to Diagnosis and Testing
for more information on the possible causes of the
discharged battery condition.
²Clear or Bright- Indicates a low battery elec-
trolyte level. The electrolyte level in the battery is
below the built-in indicator. A maintenance-free bat-
tery with non-removable cell caps must be replaced if
the electrolyte level is low. Water must be added to a
low-maintenance battery with removable cell caps
before it is charged. Refer to Standard Procedures for
the proper battery filling procedures. A low electro-
lyte level may be caused by an overcharging condi-
tion. Refer to Charging System for the proper
charging system diagnosis and testing procedures.
Fig. 6 Built-In Indicator
1 - SIGHT GLASS
2 - BATTERY TOP
3 - GREEN BALL
4 - PLASTIC ROD
8F - 10 BATTERY SYSTEMBR/BE
BATTERY (Continued)

STANDARD PROCEDURE - HYDROMETER TEST
The hydrometer test reveals the battery state-of-
charge by measuring the specific gravity of the elec-
trolyte.This test cannot be performed on
maintenance-free batteries with non-removable
cell caps.If the battery has non-removable cell caps,
refer to Diagnosis and Testing for alternate methods
of determining the battery state-of-charge.
Specific gravity is a comparison of the density of
the battery electrolyte to the density of pure water.
Pure water has a specific gravity of 1.000, and sulfu-
ric acid has a specific gravity of 1.835. Sulfuric acid
makes up approximately 35% of the battery electro-
lyte by weight, or 24% by volume. In a fully-charged
battery the electrolyte will have a temperature-cor-
rected specific gravity of 1.260 to 1.290. However, a
specific gravity of 1.235 or above is satisfactory for
the battery to be load tested and/or returned to ser-
vice.
Before testing, visually inspect the battery for any
damage (a cracked case or cover, loose posts, etc.)
that would cause the battery to be faulty. Then
remove the battery cell caps and check the electrolyte
level. Add distilled water if the electrolyte level is
below the top of the battery plates. Refer to Battery
System Cleaning for the proper battery inspection
procedures.
See the instructions provided by the manufacturer
of the hydrometer for recommendations on the cor-
rect use of the hydrometer that you are using.
Remove only enough electrolyte from the battery cell
so that the float is off the bottom of the hydrometer
barrel with pressure on the bulb released. To read
the hydrometer correctly, hold it with the top surface
of the electrolyte at eye level (Fig. 8).
CAUTION: Exercise care when inserting the tip of
the hydrometer into a battery cell to avoid damag-
ing the plate separators. Damaged plate separators
can cause early battery failure.Hydrometer floats are generally calibrated to indi-
cate the specific gravity correctly only at 26.7É C.
When testing the specific gravity at any other tem-
perature, a correction factor is required. The correc-
tion factor is approximately a specific gravity value
of 0.004, which may also be identified as four points
of specific gravity. For each 5.5É C above 26.7É C, add
four points. For each 5.5É C below 26.7É C, subtract
four points. Always correct the specific gravity for
temperature variation.
EXAMPLE:A battery is tested at -12.2É C and has
a specific gravity of 1.240. Determine the actual spe-
cific gravity as follows:
(1) Determine the number of degrees above or
below 26.7É C:26.7É C + -12.2É C = 14.5É C below
the 26.7É C specification
(2) Divide the result from Step 1 by 5.5É C:14.5É
C ÷ 5.5É C = 2.64
(3) Multiply the result from Step 2 by the temper-
ature correction factor (0.004):2.64 X 0.004 = 0.01
(4) The temperature at testing was below 26.7É C;
therefore, the temperature correction factor is sub-
tracted:1.240 - 0.01 = 1.23
(5) The corrected specific gravity of the battery cell
in this example is 1.23.
Fig. 7 Built-In Indicator Sight Glass Chart
Fig. 8 Hydrometer - Typical
1 - BULB
2 - SURFACE COHESION
3 - SPECIFIC GRAVITY READING
4 - TEMPERATURE READING
5 - HYDROMETER BARREL
6 - FLOAT
BR/BEBATTERY SYSTEM 8F - 11
BATTERY (Continued)