42-volt electrical systems coming fast

21 December 2001: Nearly 3 million cars will be equipped with 42-volt batteries by 2006, leading to reduced emissions and better fuel consumption as the job of powering the vastly-increased number of electrical accessories in the modern car is shifted from the engine back to the battery.

Experts promise at least a 10-percent fuel economy improvement, and perhaps much more, though the costs of developing 42-volt systems will probably represent an extra EUR 1,300 per vehicle by then.

The 12-volt battery has been around for 45 years, before which most systems were half that voltage. The idea to go 42-volt was first proposed in 1994.

The new 42-volt battery and a combined alternator/starter will enable “stop-start,” which shuts down the engine at traffic lights, and even sometimes in very bad traffic. But the battery also helps fuel efficiency by removing the drain of belt-driven systems like power steering, which is already being operated in some European cars by electricity instead of motor power.

Most electrical systems currently in cars, such as lighting, can’t handle the higher voltage. So carmakers must either redesign all those components, or include both a 42-volt and a 12-volt battery in cars and slowly phase out older systems.

The extra voltage poses some safety issues. While 42 volts was intentionally selected as the highest voltage available without posing serious health risks, there can be risks when reconnecting and disconnecting components.