12-volt electrical systems are reaching the end of the road

The pace of change in vehicle technology has been dizzying in recent years with engines, brakes and safety systems all undergoing radical transformations that have brought dramatic improvements. They don’t make cars like they used to, and we can all be very thankful for that.

However one thing that’s remained unchanged for decades is the electrical system that underpins much of this technology. Cars have been running 12-volt electrical systems since the 1950s when most manufacturers switched from 6 volts. There are strong indications that all that’s about to change with a move towards 48-volt electrical systems becoming the norm.

Audi electrical system infographic

Renault and Audi are two manufacturers leading the charge. Audi is looking to a 48-volt electrical system in its upcoming RS5 to power an electric supercharger and other components. Renault’s new Scenic will be using a 48-volt system in its hybrid drive. The Scenic’s system is actually a 48/12volt system using different voltages for different applications. Mercedes and Fiat-Chrysler have also said they’ll be moving to 48-volt architecture in the future.

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Increasing electrical workloads

So what’s behind this relentless drive to 48-volt systems? Well quite simply the increasing demands modern cars make on their electrical systems means that 12-volt systems are reaching the end of the road. Modern vehicle electrical systems are increasingly being asked to support sophisticated components for autonomous driving, electrical drivetrain components, like oil and water pumps, hybrid-drive technology and increasingly powerful computers. 48-volt systems are better suited to these tasks.

At the heart of these new systems is a compact 48-volt lithium ion battery capable of handling the workload. But not all components will be 48 volt, with lights, radios, electric windows and other components still powered by 12 volts.

Fuel savings

48-volt systems promise motorists significant fuel savings because they can efficiently power hybrid powertrains and better stop-start systems. That’s important to American vehicle manufacturers driven by stringent mandatory fuel consumption targets. But it’s also crucial to European manufacturers like Volkswagen who are looking to mild petrol-hybrid systems to pass tough emission standards.

“Today diesel engines are more expensive [than petrol engines] and this distance is going to grow as we have to work to tougher standards,” said VW’s development head Dr Frank Welsch. “We have enough customers for diesel in cars like Polo now, but that might not be the case forever.”

“A 48-volt mild hybrid would work on Polo and Golf,” Dr Welsch said. “It offers better recuperation and near silent start/stop so you don’t feel the engine cutting out and starting. With a cruising function also you will achieve savings starting at around six to eight g/km of CO2 and in real-life conditions.”

Fellow German BMW also has plans to adopt a 48-volt system to power mild-hybrid technology across its entire range, with the first of them coming onto the market by 2020.

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Categories: Technology, Electric
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