The main function of the electrical system in a vehicle is to generate, store, and supply the electric current

to various systems of a vehicle.

It operates the electrical components/parts in vehicles.

Most components of the earlier-generation vehicles were predominantly mechanical in nature and operation.

Over the amount of your time,

these components started operating electrically/electronically;

shedding their pure mechanical function which the sooner vehicles used.


the bulk of vehicular systems have an electrical function for simple operation and precision control.

Even more advanced steering systems like electrical power Assisted Steering (EPAS) also operate by electrical power.


the engineers felt the necessity for consistency within the generation of electrical power.


they employed different mechanisms to effectively generate, regulate, store, and provide the electrical current within the vehicles.

Negative Earth:

Earlier generation cars mostly used the positive ground in their electrical system.

During this system,

the positive terminal of the battery was attached to the chassis while the negative terminal was live.

However, later this technique was discontinued.


modern cars make use of the negative earth in their electrical system.

Generally, most cars use the 12 Volts electrical system.


some small bikes still use the 6 Volts system

whereas some commercial vehicles use the 24 Volts system.

The vehicle electrical system consists of the subsequent main components:

  • Magneto
  • Generator
  • Alternator
  • Cut Out/Voltage Regulator
  • Battery
Vehicle Electrical System: Magneto

Magneto is an electrical device that generates periodic pulses of AC.

However, it uses permanent magnets

. The magneto doesn’t have a ‘commutator’ which produces the DC (DC) sort of a Dynamo.

Manufacturers classify the magneto as a kind of an alternator.


it’s different from other alternators that use field coils rather than permanent magnets.

The magneto has the following parts:
  • Set of permanent magnets
  • Coil
  • Cranking mechanism (Usually a kick during a motorcycle)


magneto converts the energy of the engine into electricity to run the engine uninterruptedly.

Magneto’s magnetic flux strength is constant.

the most advantage of the magneto is that its output is steady no matter load variations.


if the engine shuts down, then it again needs an external input to restart.


the utilization of such magnetos for ignition is extremely limited.


there are a couple of motorcycles, small bikes, and quads that still use the magneto system.

the most advantage of this technique is reduced weight.

Initially, you would like the input from the battery to start out the engine.


the magneto generates electricity from the input of the energy.

Vehicle Electrical System: Dynamo/Generator

A Dynamo/Generator may be a device that converts energy into electricity.

It supplies the electricity for charging the battery of a vehicle.

The generator gets the drive from the engine, generally thru’ the belt.

In earlier generation vehicles, you’ll see this sort of arrangement.

The speed of the generator largely depends on the speed of the engine.

because the engine speed increases; so does the speed of the generator.

It varies to an excellent extent throughout the engine’s speed like its power-band.


things demands that the generator output should remain nearly constant.

Also, another name for the automotive Generator is Dynamo.

Furthermore, the automotive generator produces DC (DC).

this is often because the electrical components need the DC to function.

Automotive applications most ordinarily use the Generator made from shunt winding.

Initially, manufacturers employed generators to supply DC (DC) which the opposite electrical components/gadgets could directly use/consume.

However, now, the Generator is replaced by the Alternator which generates AC (AC).

it’s then converted into the DC (DC) with the assistance of diodes.

The main components of a generator are:
  • Frame
  • Armature
  • Field coils

Vehicle Electrical System: Alternator

The Alternator is additionally referred to as the AC Generator.

it’s a tool that produces an AC (AC) rather than DC (DC).

Hence, it’s referred to as an Alternator and works on an equivalent principle.

within the early 60s, the alternator replaced the DC Generator due to its distinct advantages over the latter.

However, the automotive electrical system only uses the DC.

So, you would like a mechanism to convert the AC to DC.

An alternator converts the AC (AC) to DC (DC) with the assistance of diodes.

The main components of an alternator are:
  • Frame or housing
  • Rotor (with electromagnets)
  • Stator
  • Slip ring and bushes

Vehicle Electrical System: Cut-Out Relay

The Cut-Out mechanism regulates and cuts out the present output getting to the battery.

When the engine is running at very slow speeds,

the generator output is typically less than the battery output voltage of 12 volts.

Hence, it’s insufficient to charge the battery.

In such a scenario, the battery starts to empty out into the generator because the battery voltage is above the generator output.

to stop the battery from draining off, manufacturers employ a voltage regulator/Cut-Out. It connects/disconnects the generator from the battery.

When the generator output is less than battery voltage,

then it disconnects the generator from the battery,

whereas when the output is higher, it connects the generator back to the battery.

Thus, it prevents the battery from discharging at slow engine speeds.

Vehicle Electric System: Battery

The main purpose of A battery is to store the electricity within the DC form for future use.

A car or motorcycle battery is simply like all other battery that has two poles: positive and negative.

Modern cars use the negative earth technology.

The positive pole represents the South Pole while the negative pole represents the North Pole .

The positive terminal is usually bigger in diameter than the negative terminal. this is often to stop it from being potentially fitted in a wrong way.

Electric Vehicles use more advanced type ‘Lithium-Ion’ or ‘Li-Ion’ batteries.

These batteries can store more current and take less time to charge compared to standard batteries.

Li-ion batteries have high energy density and low self-discharge properties. Hence, they provide long hours of operation before needing the re-charge.

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