48 Volts Mild hybrid system, the affordable Electrification

The 2030 CO2 reduction targets are unreachable without automotive hybridization. The Valeo 48-Volt powertrain system architecture is a hybridization solution suited to all types of vehicles, allowing significant gains compared to a 12 Volts hybridization system and a full electrification solution for light vehicles.

What is a 48V Mild Hybrid System?

A 48V mild hybrid system is a hybrid electric vehicle technology that uses a 48-volt electrical system in addition to the conventional 12-volt system found in most cars.

The 48V system typically includes a 48V lithium-ion battery, a belt-driven integrated starter-generator (BISG), and a DC/DC converter.

What are the benefits of the 48V mild hybrid technology?

Cars with 48V-volt technology promise many advantages:

  • Weight reduction
  • Small size: don’t impact interior space
  • Fuel efficiency: reduction of fuel consumption and thus CO2 emissions
  • Affordability: less expensive than a full hybrid system

Valeo 48V Hybrid system

Reaching the voltage level to 48V maximizes the hybrid system benefits in terms of CO2 reduction and fuel economy. This powertrain system, which can be used in either 100% electric or hybrid vehicles is on average 20% more affordable than high-voltage motors (greater than 60V), thanks to a simplified architecture that reduces safety equipment requirements.

Valeo offers two levels of 48V hybridization:

Hybrid4all: 48V hybrid system affordable for everyone

  • Level 1 – the Hybrid4all 5% fuel savings with increased comfort and power (compared to 12 Volts system).
    • Regenerative braking, storage of the energy in the 48V lithium-ion battery.
    • Torque assist: the 48V starter generator uses the recovered energy to assist the internal combustion engine when accelerating.
    • Electrical supply: the energy stored in the 48V lithium-ion battery is fed through the 48V converter, in order to supply the vehicle’s electrical network in order to power the accessories (car radio, windscreen wipers, and so on.).

48V hybrid system with electric propulsion

  • Level 2 – hybrid with 100% electric propulsion: around 15% fuel savings with greater comfort and power.
    • Level 1, with an added 48V electric propulsion engine.
    • Combined with a high-capacity battery, the vehicle can be driven in 100% electric mode.
    • Similar performance to a high-voltage hybrid system.


Valeo’s 48V electric motor range

Valeo’s range of 48V electric motors meets the different needs of the existing motor hybridization range. This 48 Volts offer includes different electric motors whose power changes according to the need:

  • Valeo’s 48V starter-alternator, from 4 to 6 kW, has already been sold in more than 1 million units, and was developed using the know-how acquired with the 12V starter-alternator;
  • The 48V 15 kW electric motor, which is oil-cooled and can be fitted to a hybrid dual-clutch gearbox, will go into series production in 2021;
  • The 48V 25kW water-cooled electric motor can also be positioned on the rear axle of the vehicle to provide an electric 4WD (four-wheel drive) function and enhance the driving experience.


In parallel, Valeo is also producing the 48V power converter (DC/DC converter) that transfers the energy stored in the battery to the vehicle’s 12 Volts on-board power supply. The series production began in 2017 with an air-cooled version that meets the cost-performance requirements. A new generation launched in 2021 is capable of meeting all energy needs thanks to its adaptable air or water cooling.

The Valeo solutions include an additional 48 Volts lithium-ion battery, a 48V converter, a new 48V starter generator and a range of electric motors which incorporate new functions:

  • Regenerative braking, from which the energy is stored in the 48V lithium-ion battery.
  • Torque assist: the 48V starter generator uses the recovered energy to assist the motor when accelerating.
  • Electrical supply: the energy stored in the 48V lithium-ion battery is fed through the 48V converter, in order to supply the vehicle’s electrical systems.

Going further: the plug-in hybrid vehicle

The first 48V low-voltage rechargeable vehicle

Resulting from its pursuit of excellence in the development of the 48V system, Valeo now offers the very first 48V low-voltage rechargeable vehicle. The Four-Wheel drive electric architecture (including a 48 Volts starter-alternator and a 48V electric motor on the rear axle) significantly improves the way to handle harsh weather conditions such as snow. By combining 48V hybridization with a larger 48V battery, this plug-in hybrid solution offers an electric range of up to 80 km, thereby guaranteeing a drastic overall reduction in CO2 emissions.

Valeo 48V plug-in hybrid is economical

This solution enables all-electric travel for around 40 kilometers, the thermal engine taking over for longer journeys. Using geolocation, the 100% electric mode is automatically activated when the vehicle enters a low emission zone. Furthermore, when a driver enters a route into the GPS, the vehicle can adapt the use of the electric drive system accordingly. Compared to conventional high-voltage plug-in hybrid vehicles, the Valeo 48V plug-in hybrid system is more economical, as the average cost of the 48V technology is around 20% lower.

48V, for full electric mobility

Tomorrow’s electric mobility will not be limited to passenger cars. Valeo proposes to apply the 48V technology initially developed for hybrid vehicles to all the new mobility applications such as light 2, 3 or 4 wheels. Valeo supplies the Citroën AMI’s engine.

Valeo eCityCar

This 100% electric prototype, operating at low voltage of 48V, is the very first 48 Volts democar powered entirely by Valeo (excluding batteries).

This two-seater electric vehicle can reach a maximum speed of 100km/h and has a range of 150km. Its small size and weight make it the perfect transportation for short journeys and city trips. It can be recharged at any electric charging point.

Valeo’s 48V 100% electric vehicle is also, and above all, more economical (20% less expensive) than a current all-electric solution, as its low-voltage system does not require any specific protection, whereas current high-voltage electric vehicles are subject to restrictive regulations and accreditations. The cost of a small 48V 100% electric vehicle could therefore be around €7,500 (after deduction of purchase subsidies).

This type of vehicle equipped with Valeo’s solution has given manufacturers the impulse for the new era of low-voltage urban mobility, which arrived on the streets of French cities in 2020 with the very first full electric 48V Citroën AMI.