The Birth of the 48V System

The use of batteries in automobiles dates back to 1918, and by 1920, 6V systems became common. However, as internal combustion engines grew in displacement and high-compression engines emerged, the 6V system fell short. In response, the 12V system was introduced in the 1950s. Most vehicles today use a 12V system with a current of 300 amperes to power onboard electronics. As vehicles integrate more energy-intensive components like electric steering, electric suspension, turbochargers, and even driver assistance systems (ADAS), the traditional 12V bus can no longer keep up with the power demands. The rise of autonomous vehicles, which rely on sensors, cameras, and LiDAR, further intensifies the need for a more capable power distribution system.

The 48V system emerged as a solution to these challenges. As more electric vehicles (EVs) hit the market, the benefits of adopting a 48V power system have become evident, providing a more efficient energy source for high-power electronic systems.

The Birth of 48V Mild Hybrid Systems

In 2011, Audi, BMW, Daimler, Porsche, and Volkswagen jointly introduced the 48V system to meet growing onboard power demands and comply with stringent 2020 emission regulations. This led to the development of the LV148 standard for 48V systems. The choice of 48V is deliberate, as it falls below the 60V safety threshold, which means that additional protective measures are not required.

A 48V system stores more energy than a 12V system and can power vehicles for longer periods without restarting the engine, reducing fuel consumption. The addition of a 48V battery supports the drivetrain and chassis, allowing engineers to either design systems that handle 48V input or use a DC/DC converter to step down to 12V, preserving traditional 12V loads.

Advantages of 48V Mild Hybrid Systems

1. Safety: Being under 60V, the 48V system does not require extra safety measures, making it a cost-effective alternative to high-voltage hybrid systems.

2. Efficiency: Compared to a 12V system, the current is reduced by one-quarter for the same power, and losses are reduced by one-sixteenth.

3. Smaller Engines: With the electrical power assist of BSG/ISG, engine sizes can be reduced, lowering emissions.

4. Electrification of Accessories: High-load components like air conditioning, water pumps, and vacuum pumps can be electrified, reducing the load on the engine.

5. Reduced Losses: Raising the vehicle's electrical voltage to 48V reduces power losses and wire harness diameter.

6. Support for Larger Loads: The 48V system can handle higher-power vehicle components.

7. Improved Engine Efficiency: Electrification of the turbocharger eliminates turbo lag and improves efficiency.

8. Quicker Start: The 48V Belt Starter Generator (BSG) reduces start time, noise, and vibration.

9. Easy Integration: 48V BSG can replace 12V BSG with minimal design changes.

Tesla's Shift to a 48V Electrical Architecture

After more than a decade of 48V system development, Tesla’s Cybertruck became the world’s first low-voltage, fully 48V production vehicle. By eliminating the 12V system, Tesla integrates all electrical components into the 48V domain, improving efficiency and reducing the complexity of handling high power loads. The shift is particularly beneficial for systems like steer-by-wire, which have high electrical demands.

Cybertruck's Electrical and Communication Architecture

The Cybertruck adopts a zonal ECU approach, where each zone is connected using twisted-pair Ethernet cables, which carry both 48V DC power and data. The ring topology ensures that even if one ECU fails, others can still communicate.

Advantages of the 48V System

1. Higher Efficiency: The increased voltage quadruples power output for the same current, significantly reducing power losses and improving overall system efficiency.

2. Better Handling: Fewer wire connections result in a cleaner design and more stable performance, particularly for low-power components. This enhances vehicle handling and production efficiency.

3. Weight Reduction: The smaller current in the 48V system allows for thinner wiring, which reduces system weight. For example, early Tesla Model S vehicles had 3km of wiring, whereas newer models, using a modular wiring patent, reduce this to 100m.

4. Improved Power Transmission: The 48V system boosts power transmission efficiency while handling higher electrical loads, reducing overall weight and further enhancing efficiency.

5. Scalability: The 48V system’s scalability is a key consideration for EV consumers. Tesla’s shift to this architecture reflects the growing trend in the industry, offering greater flexibility and enhancing the performance of electric vehicles.

In conclusion, as the demand for high-power vehicle components increases and manufacturers seek to improve efficiency, the 48V power system is becoming a critical technology for the future of electric and hybrid vehicles. The advantages it