In automobiles, a 42-volt electrical system was an electrical power standard proposed in the late 1990s. It was intended to facilitate increasingly-powerful electrically-driven accessories in automobiles, and lighter wiring harnesses. Electric motors were proposed to be used for power steering or other systems, providing more compact installations and eliminating the weight of drive belts or large wires for high-current loads.
The proposed new standard was exactly triple the voltage of existing "12-volt" systems. The higher voltage was selected to provide greater power capacity for wiring and devices on one hand, and to stay under the 50-volt limit used as a guideline for electric shock hazard. The European auto manufacturer Daimler-Benz proposed a 42V brand name for the conversion.
Although many manufacturers were predicting a switch to 36-volt (lithium-ion battery) / 42-volt (charging voltage) electrical systems, the "42V" changeover did not occur by early in the 21st century, and plans were mostly abandoned by 2009.[1] The availability of higher-efficiency motors, new wiring techniques and digital controls, and a focus on hybrid vehicle systems that use high-voltage starter/generators largely eliminated the 2000s cross-industry push for raising the main automotive voltages.[1] Applications that once were thought to require higher voltages, such as electrical power steering, were subsequently achieved with 12-volt systems.[1] In the late 2000s, 42-volt electrical components were used in only a few automotive applications, since incandescent light bulbs work well at 12 volts and switching of a 42-volt circuit is more difficult.[1][2]
In the 2010s, 48-volt electrical systems became popular.