BATTERY
INTRODUCTION:
The
Battery is the main part of the electrical system in an
Automobile.
The battery supplied current for operation of the starting
motor
and ignition system when the engine is being cranked for starting. It
also
supplies current for light, radio, heater and several other accessories.
Types of
batteries:
1. Lead acid battery
2.
Alkaline battery
a) Nickel iron type
b) Nickel cadmium type
3. Zinc
Air battery
LEAD
ACID BATTERY: The lead
acid battery is most widely used in
automobiles.
It consists of the following components.
1.
Container
2.
Plates
3.
Separators
4. Cell
covers
5.
Electrolyte
1.
Container: It is a
single piece construction and is made of hard
rubber
or bituminous material. It is divided into compartments by partitions
for
different cells.
2.
Pates:
The
plates in the battery consists of perforated grids into
which
lead or lead peroxide has been pressed. There are two types of
plate
groups in each cell positive plate group and negative pate group.
The
plate group connected to the positive terminal of the cells consists of
the
grids filled with a paste of Lead Peroxide. The negative plate group
consists
of Metallic lead.
3.
Separators:
Separators are placed between the negative and
positive
plates to keep them separate with each other. These are usually
made of
special treated wood, hard rubber etc.
4
Cell Cover:
Each
cell is covered by a cover of hard rubber through
which the positive
and negative terminals project.
5
Electrolyte:
The
electrolyte used in the lead acid battery is the
solution
of sulphurise acid. It consists of 40% of sulphuric acid and 60% of
AUTO
TRANSMISSION SYSTEM distilled water. The level of electrolyte
should
be amount 10 mm over the tops of the plates
.
CHEMICALS
USED IN BATTERY:
The
chemicals used in a Battery are as follows
1.
Sponge Lead (Solid)
2. Lead
Oxide (Paste)
3.
Sulphuric Acid (Liquid)
BATTERY
EFFICIENCY:
The
capacity of a fully charged battery falls down to a much
lower
value in fully discharged state. To know the capacity of
battery two
methods are adopted.
BATTERY
TESTING:
A
battery can be tested to ascertain its condition by the following
tests.
1.
Specific gravity test
2. Open
Volt test
3. High
discharge test
4.
Cadmium tip test
Specific
gravity test: While the chemical reaction taking place
in the
battery during discharge, the electrolyte becomes dilute to
form
water. The proportion of water goes on increasing as the
discharging
continues. The relative amounts of water and acid is
determined
by the specific gravity test. This is done by Hydrometer.
The
Meter of Hydrometer ranges as follows:
Reading
Condition
1.260 to
1.280 Fully charged
1.230 to
1.250 ¾ charge
1.200 to
1.220 ½ charge
1.170 to
1.190 Very little charge
1.110 to
1.130 Completely discharged
ii)
Open Volt test:
The Open
circuit voltage of a fully charged
battery
cell is about 2.1 volts. This can be measured with the help of
a
voltmeter. It can be observed that a charge of 0.01 Volt of open
circuit
voltage is equivalent to a charge of 0.010 in the specific
gravity
of the electrolyte.
High
discharge test:
High
Voltage of current is required for
cranking
the starting motor. To satisfy this condition, high discharge
test is
done with the help of cell voltage tester.
Cadmium
Test:
The test
is done to ascertain whether the battery
plates
are defective or not. It is done with help of cadmium rod
enclosed
in a perforated ebonite tube. The rod is immersed in the
electrolyte
and connected to the negative terminal of a Voltmeter.
Its
positive terminal is connected alternately to the positive and
negative
terminals of a battery cell. When connected with positive
terminals,
the voltage reading should not be less than 2.5 Volts. If it is
less it
indicates defective positive plates. When connected with
negative
plates, if it is more than 2.5 Volts, it indicates defective
negative
plates.