Electronic Design

Coming Soon: 42-V Automotive Systems

Car makers are more certain than ever that the much publicized 42-V car battery will become a reality soon, replacing the standard 12-V battery. This conviction is driven by federally mandated emissions and fuel economy legislation, as well as increasing power loads as more electronics features enter the automobile. Automotive market analysts are confidently predicting that in two years, 20% of all cars will have 42-V systems, and 60% by 2010. Several auto makers, like Toyota, Ford, and Daimler Chrysler, have already introduced or soon will have 42-V systems, some being hybrid versions with both 42 V and 12 V available.

Industry working groups are trying to come up with suitable standards for 42-V systems, hopefully by next year. One standard, the ISO 21848, specifies such parameters as maximum steady-state and reverse voltages. The focus is on the lead-acid battery as the battery of choice due to its lower cost.

The reason for a 42-V battery is simple: It’s the most cost-effective means presently known to meet constantly developing and ever-tougher fuel-efficiency and emissions standards. That is, unless auto makers come up with a new breed of power-train technology, which is very costly in terms of capital investment. One feature of a 42-V system is a so-called "idle-stop" mode, in which a car’s engine shuts down automatically while stopped at a traffic light or in bumper to bumper traffic, substantially saving on gas consumption.

This new industry push for a 42-V car system is in sharp contrast to the strong resistance automotive engineers put up just a couple of years ago to this idea. In fact, many automobile companies had invested more into improving present 12-V systems than to go to 42-V batteries. But then again, when auto makers switched from the old 6-V battery to the now 12-V system in the mid 1950s, it took them over a decade to do so, yet they eventually all did.

With stronger government regulatory pressures and the desire to add more electronics-based features to a car, which requires a lot more power, auto makers now face an inevitable fact: They have no choice but to move to 42-V systems, and must do so soon if they want to stay competitive. As more features are added, higher-voltage batteries would require lower currents, which translates into thinner wiring harnesses.

Some of those features include variable engine-valve timing, heated steering wheels and windshields, electric power steering and braking, and a host of telematics safety and entertainment functions. Automotive experts also point out that future plans to include collision-avoidance systems and adaptive cruise control would be simplified a lot with the availability of 42-V systems.

The move to 42-V systems also opens up new markets for suppliers of automotive power devices. Load controller, voltage regulator, driver, MOSFET, IGBT, dc-dc converter, and current- and voltage-monitoring ICs are being introduced or about to become available from leading semiconductor companies. So are high-power relays. As one industry analyst puts it, "42-V batteries will be key enablers for the next evolution in automotive electronics."

TAGS: Automotive
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