[url]http://www.caraudiomag.com/specialfeatures/0307cae_42volt/[/url]

42-Volt Autos

The possibilities for car audio are going to be almost limitless with the 42-volt industry standard

By Mike Klasco
Photography: Rohit Rao

Beginning in 2004, the U.S. auto industry will begin its move from the 12-volt battery (14 volts at the generator/alternator) electrical systems toward a 42-volt standard, with 25 to 50 percent of new vehicles incorporating 42V electrical architectures by 2010, and all new cars by 2020. A 42-volt system will slash weight, improve fuel economy, permit the replacement of many mechanical parts with electrical ones, power all sorts of new gizmos like seat heaters, video, etc, and, of most concern to us, improve efficiency for all automotive electrical devices, opening the door to higher audio amplifier power with far less complexity than the current crop of 12-volt, high-power amplifiers. Not only can will this translate to lower cost and more compact aftermarket power amps, even head units could cheaply integrate 100-plus RMS watts per channel power.

A New Standard
The standard that was recently agreed to by automakers and suppliers in Europe and the U.S. is a 36-/42-volt standard. Specifically, it is a tripling of the current voltage for both battery output (from 12 to 36) and generator voltage output (from 14 to 42). Vehicles with these next generation electrical systems will likely have dual batteries (12-volt and 36-volt) or at least a stepped-down, 12-volt circuit on board so that all electrical components don't have to change over at once. This will be more expensive, but the auto industry is very conservative, and this is the safer way to do it.

Aside from the pressure to meeting state and national standards on automotive fuel efficiency and emissions, the movement to 42-volt electrical systems is being stimulated by a seemingly insatiable demand for electrical and electronic accessories in vehicles, from heated windshields and seats to dash-mounted navigation systems and rear-seat TVs. Expect the first vehicles to switch to this new electrical system to be the big SUVs, premium luxury cars, and hybrid gas/electrical vehicles. Currently, bulky wiring harnesses, heavy power motors, and electronics that are subject to voltage sags and spikes which form some of the compromises of 12-volt systems. Moreover, the potential of breakthrough components like electronically actuated valves, flywheel starter/alternators, electric brakes, active suspensions and, four-wheel steering systems continues to go largely unrealized because there just isn't enough electrical power. More volts mean rethinking everything from light bulbs to the audio systems.


Rest of the story at the link.

Mercedes-Benz has been looking at 42V systems for years. It is integral to their instant ignition system. This system shuts the engine down at a stop, and then refires the ignition as the throttle is opened. There are also components which reduce the emissions in this "hot" startup condition. I think the 42V systems will usher in a whole new way of dealing with automobile power systems.

Terrific! My neighborhood needs louder car stereos.[rolleyes]