Singapore –
Audi announced today that it will begin upgrading the electrical systems of its future vehicles  to 48V. Currently, all conventional automobiles (not hybrids or EVs) use 12V electrical systems.

The reason for this is to improve ‘bandwidth’ for electricity in cars. “We are using the full bandwidth of electrification in our drive principles strategy. Running part of the vehicle electrical system at 48 volts plays a central role in this,” says Prof. Dr. Ulrich Hackenberg, Member of the Board of Management for Technical Development at Audi. “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.”

How is this possible? There are three basic principles when it comes to electricity. Electricity itself is the flow of electrons (hence the name). Voltage is the potential for electric flow and is always measured as a difference between two points – it’s most commonly likened to water pressure. For example, a water tank in a high place has a high potential for flow, likewise something with high voltage. 

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Current, measured in amperes, is the actual flow of electrons or electricity in a circuit, and the impedance to this flow, which arises from wires or materials, is called resistance, measured in Ohms. According to Audi, current automobile alternators (which generate electricity for on-boad consumers such as the air-conditioning and lights) max out at three kilowatts.

The relationship between the voltage and current is inverse, that is, if higher voltage is available, less current is needed. More current generally means more resistance, more heat, and larger, heavier wiring looms and circuits needed to overcome resistance.

The solution is a second 48V electrical system, which could be connected to a more compact, but higher capacity lithium-ion battery and a more powerful alternator capable of up to 10kW. This has a wide number of potential applications: to improve start-stop performance, run air-conditioning more efficiently or even power electric turbochargers, as seen on the Audi RS5 TDI concept car. 

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 Electron ‘Charged’

Back in May 2013, we tested Audi’s electric turbocharger system in a prototype A6 3.0 TDI machine. The electric compressor concept is simple: Unlike a conventional turbo, the electric one can run off the car’s battery and alternator system (presumably a 48V one as mentioned). Similar to BMW’s tri-turbo setup in the M550d models which has two smaller turbos and one big turbo daisy-chained, the electric turbo can ‘pre-charge’ the intake gases before the conventional turbos kick in, eliminating turbo lag. It’s not meant to replace conventional turbos either, since they already run on ‘free’ energy from exhaust gas. As we noted in our hands-on test drive, the electrically-charged A6 TDI suffers zero turbo lag with the system engaged, and estimate it could shave off half a second in a 0-60km/h sprint.

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