Subject: Automobile Engineering

Topic: Electrical System, Starting Systems & Alternator

Difficulty: Medium

i) Charging System- The modern charging system has not changed much in over 40 years. It consists of the alternator, regulator & the interconnecting wiring.

The purpose of the charging system is to maintain the charge in the vehicles's battery & to provide the main source of electrical energy while engine is running.

If the charging system stopped working, the battery's charge would soon be depleted , leaving the car with a "dead battery". If the battery is weak & the alternator is not working, the engine may not have enough electrical current to fire the spark plugs, so the engine will stop running.

If the battery is "dead", it does not necessarily mean that there is anything wrong with it. It just depleted of its charge. It can be brought back to life by recharging it with a battery charger or by running the engine so that the alternator can change it.

The main component in the charging system's Alternator. The Alternator is a generator that produces alternating current.

This current is immediately converted to direct current (DC) inside the alternator. This is because all modern automobiles have a 12 volt, electrical system. A voltage regulator regulates the charging voltage that the alternator produces, keeping it between 13.5 & 14.5 volts to protect the electrical components throughout the vehicle.

ii) Starting System:
An automotive engine can be started by cranking it either by means of a handle or any other device. A good amount of effort is required to start the engine by handle. Instead of using a handle, a device called the starter, is generally used. It applies the same amount of efforts or torque to start the engine.
The starter is an electrical motor which can rotate the crankshaft in order to start the engine.
The starting of cranning system consists of a starting motor, battery, control switch & interconnecting wiring. The performance of all these components must be matched against engine requirements for satisfactory service.
The starting motor are mostly of direct current series motor. These convert the electrical energy supplied by the battery to mechanical energy by rotating the armature shaft . A drive mechanism couples the shaft through a pinion & flywheel ring gear to the engine. The starting motor consist a motor unit & drive unit.

iii) Alternator, working principle, advantages:
An alternator is used on Vehicle to charge the battery & operate the electric circuit. Alternator are much smaller, lighter in weight & produce more current than dynamo. Alternator has a set of rotating pole & a stationary set of winding. Solid state diodes used to convert AC to DC voltage. The alternator made of rotor, slip ring, brush assembly.

Working principle:- Alternator operates on the same fundamental principles of electromagnetic induction as DC generator. A rotating bar magnet furnishes the moving field which cuts a conductor induced a flow of electric current in the conductor. So, the alternator produces a current. So, the alternator produces a current.

Advantages:-
i) Smaller size
ii) Light weight
iii) produces more current