The tipping point for cars to adopt more powerful 48-volt electric systems may be near as automakers turn to small electrically powered superchargers and other systems to deliver more performance from smaller engines.
"The initial conversion will be driven by the need to make vehicles that are fun to drive," Matti Vint, powertrain research and development director for Valeo, told me in the French supplier's North American engineering center before I took a white Lincoln MKZ equipped with the system for a spin on Detroit-area roads.
The electric supercharger, bolted to a more or less stock Ford 2.0-liter turbocharged four-cylinder engine and combined with other Valeo 48-volt goodies, made a persuasive case.
Valeo's not providing figures for power or fuel economy yet, but acceleration improved markedly, and the fuel-saving stop-start system worked in a much broader range of conditions from stop lights to highway driving.
Vint says 48-volt systems with lithium-ion batteries about the size of a current 12-volt battery will also enable cars to drive short distances solely on electricity at a lower cost than current hybrids. The new parts will initially be expensive, but Vint said Valeo expect to drive them to "commodity levels" with development and rising production volumes.
The move to 48-volts would be the first major change in automotive electric systems since most cars switched from six to 12 volts in the 1950s. Luxury automakers have been touting 48-volt systems to power new features for years, but they've yet to catch on.
While 48-volt systems provide power for more advanced new systems like the supercharger and active body roll control, the wires aren't dangerous to touch, making them easier to deal with than the high-voltage systems in many hybrids.
Valeo expects 48-volt electric systems will operate in tandem with 12-volt systems in vehicles for the foreseeable future. They'll gradually spread to power fans, window defrosters, seat and steering wheel heaters.
Valeo is testing a Chinese-spec Lincoln MKZ luxury sedan with the supercharger and a number of other 48-volt features, using an elaborate system to adjust the car's operation on the fly and demonstrate 48-volt's potential.
The first production vehicle with the 48-volt supercharger is the SQ7 luxury SUV Audi sells in Europe. It uses the little supercharger to improve power _ especially torque, the key to acceleration _ at engine speeds that are too low for the V-6 diesel's twin turbochargers to be effective. The result: better throttle response. The SQ7's 4.0-liter V-8 diesel develops 435 horsepower, 664 pound-feet of torque and hits 100 kmh (62 mph) in just 4.8 seconds.
Boosting low-rpm torque also allows transmissions to downshift less often, improving fuel economy and reducing noise and vibration, Vint said.
The electric supercharger, which Valeo calls eSC, also works with turbocharged gasoline engines. That's important, because while the window may be closing on diesel car sales in the U.S., Valeo expects more than half the engines in new vehicles sold here will be turbocharged, supercharged or both by 2026.
That evolution may include automakers dropping whole families of V-6 or V-8 engines as they use different levels of boost to get a wide range of power outputs from a single family of four-cylinder engines.
Vint used a laptop and touchscreen to turn various features on and off during my test drive in the MKZ.
The supercharger made a huge difference in acceleration. The different settings for auto-stop allowed the car to shut off the engine and disconnect the transmission in neutral, potentially saving lots more fuel than current systems that only shut the engine off when the vehicle is motionless.
The benefits are obvious. They may even be enough to bring 48-volt power systems to mainstream cars and trucks after years of automakers' and suppliers' promises that came to nothing.
