Project - Analysis of a practical automotive wiring circuit

• Identify each of the major elements in the above automotive wiring diagram.

Battery

Starter

Generator

Ignition Coil

• Explain the purpose and working of any three elements briefly.

1. Battery:

An automotive battery is a rechargeble battery that is used to start a motor vehicle. Its main purpose is to provide an electric current to the electric-powered starting motor, which in turn starts the chemically-powered internal combustion engine that actually propels the vehicle. Once the engine is running, power for the car's electrical systems is still supplied by the battery, with the alternator charging the battery as demands increase or decrease.

Electric vehicles (EVs) are powered by a high-voltage electric vehicle battery, but they usually have an automotive battery as well, so that they can use standard automotive accessories which are designed to run on 12 V.

Excess heat is a main cause of battery failures, as when the electrolyte evaporates due to high temperatures, decreasing the effective surface area of the plates exposed to the electrolyte, and leading to sulfation. Grid corrosion rates increase with temperature. Also low temperatures can lead to battery failure. If the battery is discharged to the point where it can't start the engine, the engine can be jump started via an external source of power. Once running, the engine can recharge the battery, if the alternator and charging system are undamaged.

2. Generator:

An alternator is a type of electric generator used in modern automobiles to charge the battery and to power the electrical system when its engine is running. Until the 1960s, automobiles used DC dynamo generators with commutators. As silicon diode rectifiers became widely available and affordable, the alternator gradually replaced the dynamo. This was encouraged by the increasing electrical power required for cars in this period, with increasing loads from larger headlamps, electric wipers, heated rear windows, and other accessories.

Hybrid automobile replace the separate alternator and starter motor with one or more combined motor/generator(s) (M/Gs) that start the internal combustion engine, provide some or all of the mechanical power to the wheels, and charge a large storage battery. When more than one M/G is present, as in the hybrid synergy drive used in the toyota prius and others, one may operate as a generator and feed the other as a motor, providing an electromechanical path for some of the engine power to flow to the wheels. These motor/generators have considerably more powerful electronic devices for their control than the automotive alternator.

3. Starter:

A starter is a device used to rotate (crank) an internal combustion engine so as to initiate the engine's operation under its own power. Starters can be electric,pneumatic, or hydraulic. The starter can also be another internal-combustion engine in the case, for instance, of very large engines, or diesel engines in agricultural or excavation applications.

Internal combustion engines are feedback systems, which, once started, rely on the inertia from each cycle to initiate the next cycle. In a four stroke engine, the third stroke releases energy from the fuel, powering the fourth (exhaust) stroke and also the first two (intake, compression) strokes of the next cycle, as well as powering the engine's external load. To start the first cycle at the beginning of any particular session, the first two strokes must be powered in some other way than from the engine itself. The starter motor is used for this purpose and it is not required once the engine starts running and its feedback loop becomes self-sustaining.

• If the total load is 10A from battery, what should be the fuse rating?

The fuse rating should lie somewhere between these two values to allow normal operation but blow on overload. For example, if the normal expected current draw is 10A, then a fuse rated at 15A.

• Identify any two elements which are connected parallel to each other. Why they are connected in parallel?

ignition switch(ignition coil) parallel connected with current and voltage regulator they have the same difference of potential (voltage) across their ends. The potential differences across them are the same in magnitude, and they also have identical polarities.

• Identify any two elements which are connected in series. Why they are connected in series?

Ammeter is series connected with fuse the same current flows through the components in the circuit, less size of wire cable is required in series wiring. we use to protect the circuit to connect fuse & circuit breakers in series with other appliances. Series circuit don't get overhead easily due to high resistance when more load added in the circuit.