48-volt electrical system. 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.

History 
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.  During the 2010s, renewed interest arose for a 48-volt low-voltage standard for powering automotive electronics, especially in hybrid vehicles.

In 2011, German car manufacturers Audi, BMW, Daimler Benz, Porsche, and Volkswagen agreed on a 48 V system supplementing the legacy 12 V low-voltage automotive standard. 

In model year 2017, the Renault Scenic dCi Hybrid Assist was the first 48 V mild-hybrid passenger car.

As of 2018, a 48 V electrical subsystem operated production vehicles such as Porsche and Bentley SUVs. Audi and Mercedes-Benz used a 48 V subsystem in 2018 vehicles such as A6, A7, A8 with 3.0 TDI 48 V mild-hybrid, CLS, E-Class, S-Class with M256 3.0 Turbo Otto 48 V Mild-Hybrid.

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 48 V 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 12 V system, migrating the low-voltage components with highest power demand to 48 V.

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.

Benefits 
A 48 V system can provide more power, improve energy recuperation, and allow up to an 85% decrease in cable mass.

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 in dry conditions without special protective measures.  (See the article on electrical injury.)

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 48 V 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.

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.

See also 
 Automotive battery
 Extra-low voltage
 Load dump
 List of electric vehicle battery manufacturers

References 

 48 V Vehicle Electrical System – More Than Just a Bridging Technology? Dusan Graovac, Christoph Schulz-Linkholt, Thomas Blasius, 23 April 2020, EE Times/Asia.
 ISO 21780:2020(en) Road vehicles — Supply voltage of 48 V — Electrical requirements and tests

Electric power distribution
Automotive electrics