Automakers are having a tough time running all the new-fangled vehicle control and safety systems using the 12-volt electrical systems currently used today. Audi appears to be the first out of the gate to adopt a 48-volt system, but will still retain at least part of each vehicle with a 12-volt system.
“We are using the full bandwidth of electrification in our drive principles strategy,” said Prof. Dr. Ulrich Hackenberg, a member of the board of management for technical development at Audi. “Running part of the vehicle electric 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 points to its recent pair of next-generation TDI concepts, which use an electrically-driven turbocharger in addition to a traditional exhaust-driven turbocharger. But, an electric turbocharger wouldn’t be powerful or efficient enough with the current 12-volt system, hence the second, smaller parallel system running at 48 volts.
The 48-volt system has its own benefits, including needing much narrower-gauge cables, which would be lighter and more easily able to dissipate heat. And there’s a supplementary lithium-ion battery, which when used in combination with a DC/DC converter and more-powerful alternator, mean the powertrain acts like a “mild hybrid.”
The bulk of future car systems will remain 12 volts, probably to avoid needing to modify or replace all the current things that work just fine, like the power-operated windows, mirrors, interior lights, etc.
Audi says that the current R&D mules are saving 16.1 grams of C02 per mile, or one-tenth a gallon of fuel over 62 miles.
While it hasn’t been confirmed, it looks like Johnson Controls is supplying Audi with the new system, based on this Automotive News story from early last year. All of the salient points — European automaker, as early as 2015, two batteries used — line up nicely, and estimated that the approximate cost of the system at about $1,200 for each system, which is a huge investment.
Twelve-volt systems are nothing new: the Dodge Brothers were using them as early as the 1920s in North America, while several automakers, like Mercedes-Benz and Fiat used a similar Bosch-supplied one around the same time. But it took until the mid-’50s before it saw much broader use.