48V

48V refers to a nominal direct current (DC) voltage of 48 volts. It is used as a low-voltage standard in several industrial sectors, most notably in automotive traction systems and in telecommunications, data centers, and energy storage. The term can denote either the voltage rail itself or a family of equipment designed to operate from that voltage level.

In modern automotive practice, 48V systems are used in mild-hybrid electric vehicles (MHEVs). A 48V battery, typically lithium-ion, powers a belt-driven starter/generator, power electronics, and a DC–DC converter that feeds the vehicle’s standard 12V network. The system provides electric assist during acceleration, enables regenerative braking, supports higher-demand accessories, and allows engine-off operation to improve fuel efficiency. It is designed to be safer and cheaper than high-voltage traction systems while delivering modest peak power, often in the tens of kilowatts range.

In telecommunications and data centers, 48V DC distribution is a long-standing standard, used to power equipment and to supply local DC–DC converters that generate lower rails. The higher voltage reduces current for the same power, lowering conductor losses and improving efficiency, while keeping the voltage within commonly accepted safety limits for low-voltage systems. This rail is often configured with a negative return referenced to ground, a convention described in practice as -48V.

Safety and system architecture emphasize isolation, protective devices, and battery management to handle thermal and electrical risks. The 48V niche bridges traditional 12V automotive electrics and high-voltage traction systems, supporting energy efficiency gains with manageable cost and safety considerations.