News - Audi
Audi starts shift to 48-volt batteries
Fuel-saving demands will require a new battery under Audi bonnets
26 Aug 2014
By BARRY PARK
AUDI has become the first car-maker to announce it will move production cars to a 48-volt electrical system in the chase for better performance and fuel economy from its products.
The German luxury brand announced overnight that it would introduce the higher-voltage system to a range of features in future products, including electrically adjusted suspension, that would otherwise severely tax a 12-volt system.
Audi has already showcased the technology in diesel-engined versions of the RS5 two-door coupe, as well as an A6 mid-sizer, which both used the 48-volt system hooked up to an air compressor used to provide an active suspension system.
The company also says that the compressor can boost performance by acting like a supercharger “from practically zero rpm to eliminate turbocharger lag”.
“We are using the full bandwidth of electrification in our drive principles strategy,” Audi board member of technical development Ulrich Hackenberg said.
“Running part of the vehicle electrical system at 48 volts plays a central role in this. It enables us to make more energy available.
“That paves the way for new technologies with which we can make our cars more sporty, more efficient and more convenient to use.” Audi said it was moving to the higher-voltage system because advances in car technology had taken the 12-volt system to its limit.
“Especially at low temperatures, all the various staticload consumers can account for the entire power generated by the alternator, which can deliver up to three kilowatts,” Audi said in a statement announcing the move.
“The battery power is no longer capable of meeting the demands of new, dynamicload consumers such as high-performance electric compressors.” Audi said the 48-volt system would run side-by-side with the 12-volt system, and run off a lithium-ion battery normally used in hybrid cars.
“The higher voltage means smaller cable cross-sections are needed this translates into lighter cable harnesses with lower power dissipation,” it said.
“The 48-volt electrical system features new storage technologies and delivers much more power than the 12-volt system with lead batteries. That makes it an important element of the Audi strategy of electrifying various stages of the drivetrain.
“The group’s developers have already come up with a scalable platform concept, including a version that incorporates the electrically powered compressor.” According to Audi, having the separate system in place took load off the cars’ engines, improving acceleration times.
It said the lithium-ion battery would work with an efficiency-optimised alternator that qualified the drivetrain as a mild hybrid.
“Within this concept there are diverse ways of starting, controlling and deactivating the combustion engine as needed,” it said.
“The powerful alternator achieves an energy recovery output of 10 kilowatts, far more than is possible at present.
“That adds up to a saving of up to 10 grams of CO2 per kilometre, equivalent to around 0.4 litres of fuel per 100 kilometres.” The scalable system – meaning it has the potential to be used across all Audi’s products – is expected to make its debut in an all-new version of the Q7 large SUV, due sometime late next year.
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