A 48-volt DC electrical system voltage is a relatively low-voltage electrical system that is increasingly used in vehicles. It began in the 2010s as a way to increase the propulsion and battery recharge during braking for fuel savings in internal combustion engine vehicles, especially mild hybrid vehicles.[1]
Traditionally, vehicle low voltage applications were powered by a 12-volt system. In the 1990s, an attempt by a cross-industry standards group to specify a 42-volt electrical system failed to catch on and was abandoned by 2009.[2] During the 2010s, renewed interest arose for a 48-volt low-voltage standard for powering automotive electronics, especially in hybrid vehicles.[3]
In 2011, German car manufacturers Audi, BMW, Daimler Benz, Porsche, and Volkswagen[4] agreed on a 48V system supplementing the legacy 12V low-voltage automotive standard.[5]
In model year 2017, the Renault Scenic dCi Hybrid Assist was the first 48V mild-hybrid passenger car.
As of 2018, a 48V electrical subsystem operated production vehicles such as Porsche and Bentley SUVs. Audi and Mercedes-Benz used a 48V subsystem in 2018 vehicles such as A6, A7, A8 with 3.0 TDI 48V mild-hybrid, CLS, E-Class, S-Class with M256 3.0 Turbo Otto 48V Mild-Hybrid.[6]
Hyundai Tucson, Hyundai Santa Fe, Kia Ceed and Kia Sportage followed in model year 2019 with 1.6 and 2.0 turbodiesel engines supported by 48V mild-hybrid technology.
A European automotive trade association, CLEPA, estimated in 2018 that as many as 1 of every 10 new vehicles in 2025 would use at least one 48 volt device in the vehicle, covering 15 million vehicles per year.
In March 2023, Tesla Inc. revealed that the Tesla Cybertruck and next-generation vehicle would utilize a 48-volt mid-voltage subsystem as a replacement of 12V system, migrating the low-voltage components with highest power demand to 48V.[7]
In December 2023, in order to accelerate the adoption by other automakers of 48 V system voltage for automotive components, Tesla offered a "48-volt electrical system whitepaper" to all industry leaders. CEO Jim Farley confirmed that Ford had received a copy and agreed to 'help the supply base move into the 48-volt future". Tesla also adopted 48 volts for its Optimus robot.[8]
A 48V system can provide more power, improve energy recuperation,[9] and allow up to an 85% decrease in cable mass.[10]
12-volt systems can provide only 3.5 kilowatts, while a 48 V power could achieve 15 to 20 kW or even 50 kW. 48 volts is below the level that is considered safe without special protective measures.[11]
One example of where these benefits can be used is in the Gordan Murray Automotive T.50, where it uses an Integrated Starter Generator to generate power for a 48V AC compressor, without the need for a belt. This allows the engine to rev more freely and give the vehicle good AC, no matter the RPM.[12]
Another example is with the use of electric turbochargers, active suspension, and rear wheel steering systems that require a lot of power to run, and might be more responsive and capable with a 48 V system.[13]