Audi Touts 48-Volt Mild Hybrid System

Audi AG says its next-generation A8 sedan will feature a standard mild-hybrid system—but powered by 48 volts—when the flagship model bows later this year.

Use of the more powerful system will be expanded to other vehicles in coming years, starting with the A6 and A7 cars next year. Smaller Audi models will continue to use conventional batteries, according to company officials.

The 48-volt architecture teams a lithium-ion battery with a belt-driven starter/alternator to boost fuel efficiency and reduce tailpipe emissions. Audi claims the starter/alternator can start the engine much faster than previous devices, which will allow the engine to be turned off longer during stop/start operations. A traditional pinion starter will be used for cold starts.

The engine can be shut off as the vehicle slows down at speeds of less than 13 mph. When stopped, a camera sensor monitors when the preceding vehicle begins to move and automatically starts the engine.

In addition, Audi says, the hybrid system will allow the engine to be turned off for as long as 40 seconds when the vehicle is coasting at speeds between 35 mph and 100 mph.