Download Batteries (Level 2) File - Totton College

1. Batteries and Fuses
Automotive – Electrical Systems
Batteries
1. Batteries and Fuses
Automotive – Electrical Systems
The Battery
Electrical systems
require electrical
power to function.
Alternator provides
electrical power when
engine is running.
Battery provides
electrical power when
engine is stationary.
A large amount of
battery power is required
to start an engine.
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1. Batteries and Fuses
Automotive – Electrical Systems
Batteries - Active Materials
Load
Battery plates contain
active materials that react
with the electrolyte.
Electrolyte
Positive plate
Positive plate active
material is lead
peroxide, negative
plate active material
is porous lead.
Electrolyte is made
from sulphuric acid
and distilled water.
Negative
plate
Container
Separator
Fundamental battery cell
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1. Batteries and Fuses
Automotive – Electrical Systems
Batteries - Cell Construction
Plates
Positive plates
Lead straps / connectors
Plates contain grids that hold
the active material and
provide an electrical path.
Plate Groups
Alternate positive and negative
plates are grouped together,
and connected by straps.
Grid
Separators
Separators
Insulate the plates from
each other, but allow
electrolyte to flow freely.
Negative
plates
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1. Batteries and Fuses
Automotive – Electrical Systems
Batteries - Cells
An element contains plate groups and separators, and is commonly known
as a cell.
Each cell produces about 2V, so 6 cells are required for a 12V battery.
Cells are connected in series by lead straps.
Straps across end cells are part of the terminals.
Battery
terminals
Lead straps
Cell (x6)
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1. Batteries and Fuses
Batteries - Discharging and Charging
Automotive – Electrical Systems
(described using conventional current flow techniques)
Discharging
Discharging occurs when
current flows out of a battery.
Current is produced when a load
is placed across battery terminals.
Battery converts stored
chemical energy into
electrical energy.
Charging
Charging occurs when
current flows into battery.
Requires an external voltage that
is higher than the battery voltage.
On a vehicle, the charging voltage
is provided by an alternator.
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1. Batteries and Fuses
Automotive – Electrical Systems
Batteries - Chemical Action
Electrolyte chemically reacts with lead plates.
Discharging
Electrolyte hydrogen combines with
positive plate oxygen to form water.
Electrolyte sulphate combines with
lead on plates to form lead sulphate.
Charging
Current flow reverses chemical action.
Sulphate is forced back into electrolyte
and combines with hydrogen, while
oxygen returns to the positive plate to
form lead peroxide.
Process continues while voltage is
applied, until all lead sulphate is converted.
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1. Batteries and Fuses
Automotive – Electrical Systems
Batteries - Ratings
Labels on battery case indicate battery ‘rating’.
Capacity - Ampere-Hour Rating
Amount of current a battery can supply over a
given period of time (20 hours) @ 27°C (80°F).
Capacity - Cold Start Rating
Current battery can provide
over a set period of time
(30s) @ -18°C (0°F).
HEAVY
DUTY
085
DIN
EQUIV
54317
AMP
HOUR
.44 AH
CCA
SAE
370 AMPS
IEC
245 AMPS
CCA
DIN
210 AMPS
OTHER
EQUIV
RESERVE
CAPACITY
62 MINS
Capacity - Reserve Capacity Rating
Time battery can supply 25A @
27°C (80°F) before the individual
cell voltages drop below 1.7V.
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1. Batteries and Fuses
Automotive – Electrical Systems
Batteries - Case
Case is made of
polypropylene (plastic) or
a hard rubber compound.
Dividers help
separate cells.
Ribs at bottom of each
cell collect excess
material from plates.
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1. Batteries and Fuses
Automotive – Electrical Systems
Batteries - Case
Cover is sealed to
the top of the case.
Openings above each cell
for screw-in plugs or
snap-in caps, in lowmaintenance batteries.
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1. Batteries and Fuses
Automotive – Electrical Systems
Batteries - Terminals and Cables
Battery Terminals
Battery has terminals for cable
connections.
Positive terminal is usually bigger.
Common types are:
Battery Cables
Cables connect to battery
using cable ends.
Battery cables carry large
currents and are very thick.
Cables should be kept short
for ease of routing.
Postor
Side
Lug
terminal
L terminal
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1. Batteries and Fuses
Automotive – Electrical Systems
Batteries - Maintenance Free Batteries
Sealed for life, no need to
top-up with electrolyte.
Built-in relative density indicator.
 Green = fully charged.
 Black = requires charging.
 Yellow = electrolyte low.
Reservoir to collect
evaporated water.
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