How Do Hybrid Cars Work? - Myers Motor Merchandise

As the name suggests, hybrid electric vehicles (HEVs) are a combination of two different types of vehicle technology, offering the benefits of both petrol-powered and electric motors.

They can be beneficial in a number of ways: they’re greener than vehicles powered by petrol alone – and offer greater fuel efficency. But how do hybrids work?


What is a Hybrid Car And How Does It Work?

Hybrid cars offer better fuel economy through using a combination of two different engines (one petrol and at least one electric), resulting in a reduction in fuel consumption and the potential for a boost of power depending on the circumstances.

While the basic functionality remains the same, car companies frequently adapt the design of their hybrid vehicles to improve elements such as power, speed or fuel efficiency.

HEVs operate via an internal combustion engine and an electric motor powered by batteries – but rather than being plugged in to charge, the battery charges by regenerative braking and through the internal combustion engine.


What is Regenerative Braking?

In all HEVs, the electricity coms from a high-voltage battery pack (this is separate to the conventional 12-volt battery also housed in the vehicle). When conventional cars decelerate, the energy normally lost due to the heat generated by the brakes is lost – but in hybrid vehicles this energy is used to power the battery pack.


Electric Motor Drive/Assist

In some models of hybrids, the electric motor can propel the vehicle at low speeds – which tends to be where petrol engines are less efficient. This allows for better fuel economy.


The Key Components

Battery (auxilliary)

This low-voltage battery supplies electricity to power the car (and accessories) before the traction battery engages.

DC/DC Converter

Converts lower voltage DC power into higher voltage DC power in order to recharge the auxiliary battery and to run vehicle accessories.

Electric Generator

As the wheels rotate whilst braking, this generates electricity, which can then be transferred as energy back to the traction battery pack (this is the “regenerative braking” process).

Power Electronics Controller

Maintains the electrical energy flow supplied by the traction battery and controls the speed and torque of the electrical traction motor

Thermal Cooling System

Regulates the temperature of the engine, power electronics and various other components inside the vehicle.

Traction Battery Pack

This stores electricity to be used by the traction motor.


To drive the wheels, this transfers power from the electric traction motor and/or the engine.

Electric Traction Motor

Takes power from the tracktion battery pack to drive the wheels. Depending on the design, some vehicles are capable of both regeneration and drive functions.

Exhaust System

Similarly to conventional cars, this funnels exhaust gas from the engine through the tailpipe using a three-way catalyst to reduce engine-out emissions as it does so.

Fuel Filler

Another feature not dissimilar to conventional cars is the fuel filler, a nozzle used to refill the petrol tank.

Fuel (Petrol) Tank

In hybrid vehicles, the function of the petrol tank is to store fuel until it is needed.

Internal Combustion Engine

When fuel is injected into either the combustion chamber or intake manifold, it mixes with air, and is ignited by the spark plug through a combination of air and fuel.


Types Of Hybrid Car

Full Hybrid

Full hybrids have powerful electrical motors and larger batteries capable of powering the vehicle for short distances and at low speeds.

Mild Hybrid

Mild hybrids, or “micro hybrids”, which  use both an electric motor and battery as power sources, allowing the engine to shut off  whilst the car is idling (this process is known as automatic stop/start).  Full hybrids provide greater fuel economy, though mild hybrids are less expensive.

Parallel Hybrid

The most commonly-seen type of hybrid car on the market is the parallel – where the petrol engine and electrical motors are connected via a common transmission to combine the two together. This can either be a manual, an automatic, or alternatively a CVT, or continuously variable transmission.

Plug In Hybrid

These contain a larger battery pack which must be fully recharged with an external electricity source at either a domestic or public charging station. A fully charged blug in can drive for 15-55 miles depending on the model, ideal for those who mainly use their car for short commutes and can charge it nightly. If the electrical power is depleted, the car reverts to  parallel hybrid mode.

Series Hybrid

Similar in feel to an electric vehicle, this type ofhybrid is powered by the electric motor(s) alone (the petrol engine is only used to charge the battery) – and so doesn’t require a connection between the wheels and the engine.

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