Project - Analysis of a practical automotive wiring circuit

1. Major elements in the automotive diagram

• Generator
• Battery
• Starter
• Ignition coil
• Distributor
• Breaker
• Current and Voltage regulator

2. Explanation of Major Elements

Generator:

• Automobile generator - a unit that converts mechanical energy into electrical energy and performs the following functions:

1. Provides a constant and continuous battery charge when the engine is running,
2. Provides power to all systems during engine start, when the starter consumes a large amount of electricity.

• The generator is installed in the engine compartment. Due to the brackets, it is attached to the engine block, driven by a drive belt from the crankshaft pulley. An electric generator is connected in an electrical circuit in parallel with the storage battery.
• The battery is charged only when the generated electricity exceeds the battery voltage. The power of the generated current depends on the revolutions of the crankshaft, respectively, the voltage increases with the revolutions of the pulley with a geometric progression. To prevent overcharging, the generator is equipped with a voltage regulator that adjusts the amount of output voltage, providing 13.5-14.7V.

Why does a car need a generator?

• In a modern car, almost every system is controlled by sensors that record their different modes of operation. If all these elements worked due to the battery charge, then the car would not even have time to warm up, as the battery is completely discharged.
• So that during the operation of the motor, each system would not be powered by a battery, a generator is installed. It works exclusively when the internal combustion engine is on and is needed for:

1. Recharge the battery;
2. Provide sufficient energy for each unit of the machine's electrical system;
3. In emergency mode or at maximum load, perform both functions - and feed the battery, and provide energy to the vehicle's electrical system.

• It is necessary to recharge the battery, because when starting the motor, only the battery energy is used. To prevent the battery from discharging while driving, it is not recommended to turn on many energy consumers.
• For example, in winter, some drivers turn on the car's climate system and glass heaters when warming up the cabin, and so that this process does not go boring, they also have a powerful audio system. As a result, the generator does not have time to generate so much energy and it is partially taken from the battery.

Battery :

• A device that translates chemical energy into electricity. Batteries are composed of cells. These cells are what contain the actual energy. They store chemical energy and transform it into electrical energy on command.

How do car batteries work?

• Most car batteries rely on a lead-acid chemical reaction to get things moving and grooving. These batteries fall into the "SLI" category. SLI stands for "starting, lighting, and ignition." This type of battery provides short bursts of energy in order to power your lights, accessories, and engine. Once the battery jolts the engine to life, power for the car is supplied by the alternator. Most vehicles come with a generic SLI battery from the factor.
• A typical SLI battery has six cells. Each cell has two plates, or grids: one is made of lead, the other of lead dioxide. Each cell is able to produce about 2-volts of energy. In most car batteries you have six cells, and therefore a 12-volt battery.
• The plates are submerged in sulphuric acid that triggers a reaction between the two plates. In scientific terms, the acid acts as a catalyst.
• This acid will trigger a reaction on the lead dioxide plate, causing the plate to produce two things: ions and lead sulphate.
• The ions produced by the lead dioxide plate react to the adjacent plate to produce hydrogen and lead sulphate.
• The result is a chemical reaction that produces electrons. The electrons race around the plates and generate electricity. The electricity flows out of the battery terminals to start your engine, turn on your headlights, and play the radio.
• This chemical reaction is entirely reversible, which is why you can jumpstart your battery and continue to charge it throughout the duration of its life. By applying current to the battery at just the right voltage, lead and lead dioxide will form on the plates and you can reuse your battery, over and over again.

Starter:

• When you turn the ignition key to the START position, or press the START button, if the transmission is in Park or Neutral, the battery voltage goes through the starter control circuit and activates the starter solenoid. The starter solenoid powers the starter motor. At the same time, the starter solenoid pushes the starter gear forward to mesh it with the engine flywheel (flex plate in an automatic transmission). The flywheel is attached to the engine crankshaft. The starter motor spins, turning over the engine crankshaft allowing the engine to start. In cars with a push button start, the system disengages the starter as soon as the engine starts running.

3.

Fuse Rating

What is fuse?

• Fuse is the self-destructive protection device which is widely used in the electrical and electronic circuit. There are different types of fuses available in the market and they are cartridge fuses, automotive fuses, resettable fuses/polyfuse, semiconductor fuses, overvoltage suppression, high voltage fuses, Rewireable fuses, Striker fuse, Switch fuse, HRC (High Rupture Current) fuses etc.
• For high starting current application, we shall increase the fuse rating to 1.5 times of the full load current.
• So, for 10 A load fuse rating = 1.5 *load current
• Fuse rating = 15 Ampere

5. Elements connected in parallel

• Two Scaled Beams are connected in parallel, because if one light fails another one should glow and all lights are in parallel to each other for the same reason.
• Battery and horn switch and relay are one circuit, which closes upon the pressing of horn switch.Which in turn closes the horn and relay circuit by closing the relay contact due to the closing of previous circuit mentioned above.Relay is used due to low ampere capacity of horn switch, because horn requires more ampere.For compactness they have used small horn switch.

6. Elements connected in series

• Gas tank unit and fuel on off in series. Gas tank unit should be controlled by the fuel on off which acts as fuel regulating switch.
• Ignition coil is in series with Current and voltage regulator-voltage produced by generator is in form of AC cannot be directly supplied to battery and ignition unit before supplying it should be rectified in to DC and regulated in to constant 12-13.7 V in order to charge the battery, as generator output will not be stable as it will fluctuate with engine Rpm.