Mild Hybrid Cars Explained: How MHEV Technology Works
As the automotive industry shifts toward electrification, mild hybrid electric vehicles (MHEVs) have emerged as a cost-effective middle ground between traditional combustion engines and full hybrids. But what exactly is a mild hybrid, and how does its technology work?
Understanding Mild Hybrid (MHEV) Technology
A mild hybrid car combines a conventional internal combustion engine (ICE) with a small electric motor and a 48-volt battery system. Unlike full hybrids (HEVs) or plug-in hybrids (PHEVs), mild hybrids cannot drive on electric power alone. Instead, the electric motor assists the engine to improve fuel efficiency and reduce emissions.
Key Components of a Mild Hybrid System:
- 48-Volt Battery – Replaces the traditional 12-volt system, providing extra power for the electric motor.
- Belt-Driven Starter-Generator (BSG) or Integrated Starter-Generator (ISG) – Acts as both a motor (assisting the engine) and a generator (recovering energy during braking).
- Power Electronics – Manages energy flow between the battery, motor, and engine.
How Does MHEV Technology Work?
- Engine Assistance – The electric motor provides torque during acceleration, reducing the engine’s workload and improving efficiency.
- Start-Stop Function – The system shuts off the engine at stops and restarts it seamlessly, saving fuel.
- Regenerative Braking – Captures kinetic energy during deceleration, converting it into electricity to recharge the battery.
- Coasting & Sailing – Some MHEVs can deactivate the engine while cruising, relying on momentum to save fuel.
Advantages of Mild Hybrid Cars
- Better Fuel Economy (up to 15% improvement over non-hybrids)
- Lower Emissions (helps meet stricter regulations)
- Cost-Effective – Cheaper than full hybrids or EVs
-
Smoother Driving Experience – Enhanced stop-start and acceleration
Limitations of MHEVs
- No Electric-Only Driving – Unlike full hybrids, MHEVs always rely on the engine.
- Modest Efficiency Gains – Less impactful than plug-in or full hybrids.