BMW and Mercedes drop 42 volt system

Munich. BMW and DaimlerChrysler have dropped plans to build 42-volt on-board electrical networks in their cars.

BMW let its original 42-volt deadline (2002-2003) pass without naming a new date. DaimlerChrysler was the first large automaker to put a stop to the project.

Stephan Wolfsried, who is responsible for electrical engineering at the Mercedes Car Group, said: "Both engineering risks and costs for all the new components are incalculable. The 42-volt system no longer exists for us."

Besides, 42 volts would not provide electric traction in vehicles with hybrid engines. The electric motor of the Toyota Prius, for example, works with a maximum of 500 volts.

Boosting operating voltage had seemed to be a logical solution to meeting increasing electrical demands in vehicles.

An electrical output of about 3 kilowatts is needed in today's cars. In the future the figure will be 8 kilowatts to cope with new electric steering systems, brakes and climatic controls.

Unexpected obstacles killed the 42-volt system.

Each electrical component from an interior light to the ABS sensor would need to be redesigned for 42 volts. Or else the light needs an individual transformer, which would be expensive.

Another problem is that all plug and socket connections need to meet significantly higher standards. An electric arc, for example, could give off a hundred times as much energy through a loose contact than before

The auto industry already went through an expensive transformation 40 years ago when changing from 6 volts to 12 volts.

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