Voltage jump overdue
While 12-volt batteries have been the automotive industry standard for years, some drivers may recall a time when 6-volt batteries were the norm. Before that, when drivers started their vehicles with a hand crank, horns had a squeeze-bulb and headlamps were gas powered, cars had no batteries.
Around 1920, electric starting necessitated an on-board battery, which was typically of the 6-volt variety. With a proliferation of electrical accessories such as sealed-beam headlights, heaters and turn signals, manufacturers began using 12-volt batteries to handle increased loads.
12-volt batteries are still used in modern-day vehicles, but that reality may soon change.
In an Automotive News article by Richard Pruett, “Goodbye, 12 volts,” it’s predicted that auto electric systems incorporating 48-volt batteries may be in our near future. That’s a big jump, but changes in electrical demands have been rapid, as battery design has remained essentially static.
There are numerous reasons for a voltage jump. Even fuel economy, for reasons which only engineers may understand, can get a boost from higher voltage electrical systems.
According to Mary Gustanski, Delphi Automotive’s vice president of engineering, with fuel economy regulations tightening, vehicle connectivity becoming a reality, and autonomous driving proliferating, old-fashioned 12-volt systems have reached the end of the road.
Autonomous vehicles depend heavily upon electrical components such as cameras, radar, lidar sensors and computers. Many components of today’s cars and trucks incorporate systems like power steering, oil pumps and water pumps that are now electrical rather than mechanical. In addition, more and faster computing demands are required for vehicle connectivity to other vehicles and the driving grid.
Those needs and others cannot be adequately met with 12-volt electrical systems. A jump is in order and current prognostication suggests that the increase will be to 48 volts.
In fact, speculation has turned to reality as Delphi has been testing a 2016 European Honda Civic diesel converted to a 48-volt system.
Early test results show a fuel economy average increase of 10 percent. That’s a huge number when engineers are normally testing innovations resulting in as little as 1 percent gains. The test vehicle has a stop/start system (where the engine stops when the vehicle stops, and starts when it takes off again), which test drivers describe as “smooth and lightning fast” as compared to 12-volt stop/start features.
About a decade ago, it was also thought that the 12-volt systems and accompanying batteries were a thing of the past. At that time, however, engineers improved alternator design and output, and developments like LED lighting actually reduced demands on electrical systems.
But now, with electrification of certain mechanical components, the implements of autonomous driving already available and vehicle connectivity on the horizon, the time for 48 volts has seemingly arrived.
“Electrical architecture is not just about getting the voltage, getting everything powered and getting the signals going, it’s about the data speed,” says Gustanski. “It’s about the computing power and how you lay out the electrical system.”
Today’s cars, Gustanski says, process data at about 65 megabits, or 15,000 pieces of data, per second. “Tomorrow, it’s 1.5 gigabits,” she says, “or 100,000 pieces of data every time you blink your eyes.”
The industry might have stuck with the 12-volt standard for an undue period, but they may soon be making up for lost time if a jump to 48 volts becomes reality.
Readers may contact Bill Love via e-mail at precisiondriving@spokesman.com.
