Battery Mounting; Battery Size And Ratings; Battery - Dodge ram truck 3500 1996 Service Manual

81 - 2 BATTERY BR
GENERAL I N F O R M A T I O N (Continued)
It is important that the battery, starting, and
charging systems be thoroughly tested and inspected
any time a battery needs to be charged or replaced.
The cause of abnormal discharge, over-charging, or
early battery failure must be diagnosed and corrected
before a battery is replaced or returned to service.
D E S C R I P T I O N AMB O P E R A T I O N
BATTERY
The storage battery is a device used to store electrical
energy potential in a chemical form. When an electrical
load is applied to the battery terminals, an electrochem­
ical reaction occurs within the battery. This reaction
causes the battery to discharge electrical current.
The battery is made up of six individual cells that
are connected in series. Each cell contains positively
charged plate groups made of lead oxide, and nega­
tively charged plate groups made of sponge lead.
These dissimilar metal plates are submerged in a
sulfuric acid and water solution called an electrolyte.
As the battery discharges, a gradual chemical
change takes place within each cell. The sulfuric acid
in the electrolyte combines with the plate materials,
causing both plates to slowly change to lead sulfate.
At the same time, oxygen from the positive plate
material combines with hydrogen from the sulfuric
acid, causing the electrolyte to become mainly water.
The chemical changes within the battery are caused
by the movement of excess, or free, electrons between
the positive and negative plate groups. This movement
of electrons produces a flow of electrical current through
the load device attached to the battery terminals.
As the plate materials become more similar chemi­
cally, and the electrolyte becomes less acid, the voltage
potential of each cell is reduced. However, by charging
the battery with a,, voltage higher than that of the bat­
tery, the battery discharging process is reversed.
Charging the battery gradually changes the sul­
fated lead plates back into sponge lead and lead
oxide, and the water back into sulfuric acid. This
action restores the difference in the electron charges
deposited on the plates, and the voltage potential of
the battery cells.
For a battery to remain useful, i t must be able to
produce high-amperage current over an extended
period. A battery must also be able to accept a
charge, so that its voltage potential may be restored.
in addition to producing and storing electrical energy,
the battery serves as a capacitor, or voltage stabilizer, for
a vehicle's electrical system. It absorbs most abnormal or
transient voltages caused by the switching of any of the
vehicle's electrical components.
The battery is vented to release excess hydrogen gas
that is created when the battery is being charged or dis­
charged. However, even with these vents, the hydrogen
gas can collect in or around the battery. If hydrogen gas
is exposed to flame or sparks, it may ignite.
If the electrolyte level is low, the battery may arc
internally and explode, i f the battery is equipped with
removable cell caps, add distilled water whenever the
electrolyte level is below the top of the plates. If the bat­
tery cell caps cannot be removed, the battery must be
replaced i f the electrolyte level becomes low.
BATTERY SIZE AND RATINGS
The outside dimensions and terminal placement of
the battery conform to standards established by the
Battery Council International (BCI). Each battery is
assigned a BCI Group Size number to help identify a
correctly-sized replacement.
In addition, there are two commonly accepted
methods for rating and comparing battery perfor­
mance. These ratings are called Cold Cranking
Amperage (CCA) and Reserve Capacity (RC). Both
ratings are described in more detail below.
The Group Size number, CCA rating, and RC rating
can be found on the original equipment battery label.
Be certain that a replacement battery has the correct
Group Size number, as well as CCA and RC ratings that
equal or exceed the original equipment specification for
the vehicle being serviced. See the Battery Classifica­
tions and Ratings chart in Specifications at the back of
this group for more information.
COLD CRANKING AMPERAGE
The Cold Cranking Amperage (CCA) rating speci­
fies how much current (in amperes) the battery can
deliver for 30 seconds at -17.7°C (0°F). Terminal volt­
age must not fall below 7.2 volts during or after the
30 second discharge. 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) i t takes for battery terminal volt­
age to fall below 10.2 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.
BATTERY MOUNTING
The battery is mounted to a molded plastic tray
located in the left front corner of the engine compart­
ment. A U-nut is held in a formation on each side of the
battery tray. A holddown strap fits across the top of the
battery case. A bolt passes through the holddown strap
on each side of the battery, and is threaded into the
U-nut on each side of the battery tray.
The battery tray is fastened to the inner fender
shield with two bolts. The tray is also fastened to the