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For some time, vehicle electrification comprised of little more than the 12-volt rechargeable battery used to start a motor vehicle. Its main purpose is to provide electric current to the electricity powered starter motor, which in turn starts the conventional internal combustion engine. Once the engine is running, power for the vehicle’s electrical systems is still provided by the battery, with the alternator charging the battery as demands increase or decrease.

The 1990s saw the introduction of the first mass produced hybrid vehicle using a combination of a conventional engine and an electric motor/generator, fitted within the transmission. This type of vehicle allows for an improved miles per gallon ratio and reduced CO2 emissions, where the electric motor takes load away from the engine by assisting during acceleration and, over short distances, propelling the vehicle with the electric motor only. This requires additional energy to power the electric motor, so the introduction of an additional high voltage battery was necessary, complete with its accompanying wiring and components.

One benefit of electric motors is regenerative braking, which turns the electric motor into a generator when cruising or braking to capture otherwise wasted energy. This is then stored in a small high voltage battery for later use. These vehicles still retain their 12-volt batteries and components for comfort and convenience features.

The past 20 years have seen a gradual increase in electrified vehicle types, with their electric components and variable operating voltages. For example, mild hybrids use starter/generators and 48-volt batteries to improve miles per gallon and CO2 emissions, while also supporting the conventional 12-volt system.

Plug-in hybrids, with large high voltage batteries, extend the electric-only range of these vehicles while still retaining a conventional engine. Finally, Battery Electric Vehicles deliver electric only propulsion and, in theory, zero emissions.

Looking to the future, hydrogen powered vehicles are expected to become more prevalent once the infrastructure is ready to support them. Electrification still plays a major role within these vehicles as an electric motor propels them.

Types of EVs

The term Hybrid Vehicle is used to describe a combination of different energy sources to propel a vehicle, such as an internal combustion engine coupled with one or more electric motor/generators.

When the vehicle is accelerated, the internal combustion engine and the electric motor/generator work together to improve fuel efficiency and lower exhaust emissions.

The vehicle will include additional electronic components to operate alongside the conventional 12-volt electrical architecture, such as a DC-DC Converter, Inverter, and wiring harness.

It will also include a rechargeable additional battery, typically Nickel-metal hydride (Ni-MH) or Lithium-ion (Li-ion) which are mainly high voltage, for energy storage. This is in addition to the standard 12-volt battery.

High voltage is generally referred to as an electric component or circuit, with a working voltage of >60-volts and ≤1500-volts DC or >30-volts and ≤1000-volts AC root mean square (rms).

During braking and while coasting kinetic energy is harnessed by the electric motor/generator and converted into electrical energy which is then stored within the additional battery, this is generally referred to as regenerative braking.

If the vehicle is fitted with a Nickel-metal hydride battery, it can be recharged by regenerative braking or by internal combustion engine generated power via the electric motor/generator.

Lithium-ion batteries can be recharged via regenerative braking, engine generated power or by being plugged into the National grid.

An Electric Vehicle or Battery Electric Vehicle configuration includes a large high voltage battery, and one or more electric motor/generators for electric only propulsion, there is no onboard internal combustion engine for drive.

When the vehicle accelerates electrical current is drawn from a high voltage battery to power the electric motor/generator which achieves maximum torque at start-up.

The high voltage battery is charged by plugging into the National grid and supplemented via regenerative braking. The approximate range of these pure electric vehicles is between 80 and 300 miles.























A Fuel Cell Electric Vehicle uses hydrogen gas for fuel which is stored within a pressure tank. Electricity is then generated by combining hydrogen and oxygen within a fuel cell stack to drive an electric motor/generator.

A high voltage battery is used to store additional energy via the fuel cell stack and recovered energy from regenerative braking, which can assist the electric motor/generator during acceleration or start up, as there may be a delay in the fuel cell generating electricity, especially when cold.

This type of vehicle is similar to refuel as in a petrol or diesel vehicle, and has a range of approximately 300 miles or more, with the only exhaust pipe emission being water vapour and heat.​​​​​​​




















Series Hybrid

A Series Hybrid configuration includes a high voltage battery, electric motor, generator, and an internal combustion engine, with the unique design of there being no mechanical connection from the internal combustion engine to the driven wheels.

This means all drive must come from the electric motor connected to the driveshafts, which receives electric power from either the high voltage battery, or the generator, run by the internal combustion engine.

The high voltage battery can be recharged via the generator or by regenerative braking.

​​​​ ​​Parallel Hybrid

A Parallel Hybrid configuration includes a high voltage battery, electric motor/generator, and an internal combustion engine. The electric motor/generator and internal combustion engine are both mechanically coupled to the driven wheels to provide power.

The internal combustion engine carries out most of the work and the electric motor/generator provides assistance to reduce the load on the engine.

Recharging of the high voltage battery relies on regenerative braking and engine generated power.

Series Parallel or Full Parallel Hybrid

A Series Parallel or Full Parallel Hybrid configuration includes a high voltage battery, electric motor/generator, and an internal combustion engine.

The electric motor/generator and internal combustion engine are both connected to the driveshafts through a mechanical coupling and depending on manufacturer design, the vehicle can be propelled by electric motor alone, engine alone, or by a combination of both.

Electric only range is usually only available over short distances, typically one mile before the internal combustion engine engages. Recharging of the high voltage battery relies on regenerative braking and engine generated power.

Mild Hybrid Electric Vehicle (mHEV)

A mild Hybrid Electric Vehicle configuration includes an additional battery, (typically 48-volt, not high voltage) for energy storage, internal combustion engine, and an electric motor/generator.

The electric motor/generator is used to assist the electrical load on the conventional 12-volt electrical architecture, and via the additional battery to operate further electrical components.

The electric motor/generator can start/stop and assist the conventional engine but cannot propel the vehicle in electric-only mode. Recharging of the additional battery is available through regenerative braking or engine generated power.

Range Extended Electric Vehicle (E-REV)

A Range Extended Electric Vehicle is configured in a similar way to a Series Hybrid, with an electric motor providing drive to the wheels. However, this type will have a large high voltage battery, which gives the advantage of being able to be plugged-in to the National grid for extended electric only driving range. The approximate range in electric only mode would be between 40 and 100 miles.

Once the high voltage battery’s energy capacity has been consumed, the internal combustion engine will start and drive a generator which provides electricity, to extend the driving range via an electric motor.

​Plug-in Hybrid Electric Vehicle (PHEV)

A Plug-in Hybrid Vehicle configuration combines a large high voltage battery, electric motor/generator, and an internal combustion engine which combines the benefits of a Parallel Hybrid and an Electric Vehicle.

The larger on-board high voltage battery allows for extended driving distances using electricity only, of approximately 30 miles. When the battery capacity has been consumed, the internal combustion engine turns on and the vehicle operates as a conventional hybrid.

Recharging of the high voltage battery is carried out by plugging into the National grid and supplemented via regenerative braking.

Self-Charging Hybrid Electric Vehicle (SCHEV)

The Self-Charging HEV is almost identical to a standard Hybrid vehicle and is largely a marketing concept used by some VMs to claim environmental credentials.

​​​​ ​​Parallel Hybrid