What is the difference between 12v and 48V mild hybrid?

The core difference between 12V and 48V mild hybrid systems (MHEVs) lies in their voltage architectures and functional scalability. As a basic configuration of traditional fuel vehicles, the 12V system is mainly used for ignition, lighting, and power supply to low-power electronic devices. In contrast, the 48V mild hybrid system, through the collaborative operation of a lithium-ion battery pack (with a capacity of approximately 1kWh) and a BSG (Belt-driven Starter Generator), boosts the voltage to 48V, significantly enhancing power output capability. This system can support high-power components such as electric superchargers and active suspensions, and provide additional torque assistance (an increase of about 50%) during vehicle startup, while reducing fuel consumption by 8%-15% through braking energy recovery. In addition, the 48V architecture uses thinner cables to reduce copper usage, lowering vehicle weight and costs, and a DC/DC converter ensures compatibility with the original 12V system. Currently, 48V mild hybrid technology has gradually become popular; its cost is about 1/3 of that of high-voltage hybrid systems, while its fuel economy can reach 2/3 of the latter, making it an efficient solution that balances performance and price.