In automobiles, a 42-volt electrical system was an electrical power standard proposed in the late 1990s. It was intended to allow more powerful electrically driven accessories, and lighter automobile 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 more than 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 sensor systems, the changeover has not occurred, and the plans appear to have been cancelled. 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 has largely eliminated the push for switching the main automotive voltages. Applications that once were thought to require higher voltages, such as electrical power steering, have now been achieved with 12 volt systems. 42-volt electrical components are now 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.
The SAE discussed an increased automobile standard voltage as early as 1988.
In 1994, at the initiative of Daimler-Benz, the first “Workshop on Advanced Architectures for Automotive Electrical Distribution Systems” was held at the Massachusetts Institute of Technology Laboratory for Electromagnetic and Electronic Systems (MIT/LEES) in Cambridge, Massachusetts USA. with the aim of defining the architecture for a future automotive electrical system. From the outset, the participants in this workshop included suppliers as well as the automobile companies Daimler-Benz, Ford and General Motors.
In September 1995, various electrical systems architectures were compared at MIT using the tool “MAESTrO”, and in December 1995, in the “Conclusions” of this study, a future voltage level of approximately 40 V was defined.
In early 1996, the “Consortium on Advanced Automotive Electrical and Electronic Systems” was set up. At the ensuing workshop in March 1996, the future nominal voltage of 42 V was confirmed.
In August 1996, IEEE Spectrum published the paper “Automotive electrical systems circa 2005”.
On the occasion of the October 1996 Convergence in Detroit, Professor John G. Kassakian (MIT) gave a talk entitled “The Future of Automotive Electrical Systems” as part of the “IEEE Workshop on Automotive Power- Electronics”.