42V

42V (forty-two volts) refers to a proposed automotive electrical system architecture that uses a nominal around 42 volts to power propulsion-support systems and accessories, often as an alternative or augmentation to the conventional 12-volt system. The idea was to deliver higher power for features such as electric power steering, coolant pumps, HVAC motors, and mild-hybrid functions, while allowing for thinner wiring than a 12-volt high-current system.

Technical approaches varied, but common concepts included a 42V main DC bus with a separate 12V down-converter to supply legacy electronics, or a full 42V system feeding high-power components with appropriate safety measures. The higher voltage reduces current for the same power, which can lower wire weight and improve efficiency, but it also requires different insulation, protection, and safety standards and components rated for higher voltages and fault protection.

History and status: The 42V concept gained attention in the late 1990s and early 2000s as automakers explored mild-hybrid and start-stop solutions. Some prototypes and experimental programs advanced, but the industry did not standardize on 42V. Over the 2000s and 2010s, many manufacturers instead adopted 48V architectures for mild hybrids, while the traditional 12V system remained in use for non-motorized electronics. Today, 42V is rarely used as a vehicle-wide standard, though in some designs it appears as a transitional solution or in specific subsystems.

See also: 48V electrical system, mild hybrid, automotive electronics.