Audi has announced it will be upgrading part of the electrical system in its cars from 12V to 48V to improve performance and fuel efficiency.

ACCORDING TO THE GERMAN car maker, the move is expected to allow future proofing for further electrical systems advances while reducing engine load and thus improving fuel efficiency.

“We are using the full bandwidth of electrification in our drive principles strategy,” said Professor Dr Ulrich Hackenberg, Member of the Board of Management for Technical Development at Audi.

“Running part of the vehicle electrical system at 48 volts plays a central role in this,” commented. It enables us to make more energy available. That paves the way for new technologies with which we can make our cars sportier, more efficient and more convenient to use.”

Audi recently demonstrated the scope of the 48V electrical system in the Audi A6 TDI concept and the RS 5 TDI concept (pictured). “Both models are fitted with an electrically powered compressor. This operates independently of the engine load and therefore fundamentally improves the accelerative performance. 48‑volt technology is also ideal for realising convenience systems for dynamic chassis control. Audi will shortly be unveiling a variety of applications in this field,” a statement read.

According to Audi, current technology applications in vehicles have pushed 12V electrical systems to their limits; this is exacerbated, the brand said, at low temperatures. “Battery power is no longer capable of meeting the demands of new, dynamic‑load consumers such as high‑performance electric compressors”.

“The solution is a second subsidiary electrical system running at 48 volts, to complement the 12V power supply. The higher voltage means smaller cable cross-sections are needed; this translates into lighter cable harnesses with lower power dissipation. The 48V electrical system features new storage technologies and delivers much more power than the 12V system with lead batteries. Audi’s developers have already come up with a scalable platform concept, including a version that incorporates the electrically powered compressor,” Audi said in a statement.

How does it work? A compact lithium‑ion battery is used to supply 48V as the energy source during engine‑off phases; a DC/DC converter integrates the 12V electrical system. The lithium‑ion battery operates in conjunction with a new, efficiency-optimised alternator that qualifies the drivetrain as a mild hybrid. Within this concept there are diverse ways of starting, controlling and deactivating the combustion engine as needed. The alternator achieves an energy recovery output of 10kW, far more than is possible at present. That adds up to a saving of up to 10g/km CO2, equivalent to around 0.4L/100 km.