mildhybrid

A mild hybrid is a type of automotive hybrid propulsion system that uses a small electric motor and energy storage to assist the internal combustion engine (ICE) rather than power the vehicle on its own. Unlike full hybrids, mild hybrids cannot drive the vehicle solely on electric power. The electric motor is typically integrated with the drivetrain as a belt-driven starter-generator (BSG) or an integrated starter-generator (ISG) that draws from a high-voltage battery, commonly around 48 volts, supplemented by a conventional 12-volt system.

The electric motor provides torque assist during acceleration, enables smooth start-stop operation, and recovers energy through regenerative braking. The primary aim is to improve fuel economy and reduce emissions modestly compared with conventional engines.

The 48V battery is smaller than those in full hybrids and is charged by the engine and braking. The system integrates with existing transmissions and often shares components with the engine bay, reducing packaging complexity and cost. The 48V architecture enables features such as idle shutdown and limited electric boost.

Mild hybrids sit between conventional internal-combustion engines and full hybrids. They offer some efficiency gains and smoother operation without the complexity or price of full-hybrid systems. They cannot operate exclusively on electric power, and their electric range is effectively zero.

Since the mid-2010s, 48V mild hybrids have become common in Europe and Asia, offered by brands such as Audi, BMW, Mercedes-Benz, Ford, Volkswagen, Volvo, and others.