Audi MILD HYBRID

 

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Mild Hybrids: A New Generation of Electric Vehicle Solutions

Mild hybrids, also known as 48-volt mild hybrid systems, are the latest version of electrified hybrid drivetrains. Although designs vary from model to model, the concept and basic system are the same. A small electric motor, called an integrated starter generator (ISG), is connected to the engine and works in conjunction with the internal combustion unit to provide additional power under acceleration.

Automakers use 48-volt systems to improve performance, but they also come with an inherent fuel efficiency benefit: they share the engine load in controlled scenarios, helping to save fuel. Some companies, such as Volvo, use mild hybrid configurations with slightly different components. For example, a Volvo ISG uses a 42-volt battery.

Benefits of Mild Hybrid Systems

1. Fuel Efficiency

An obvious benefit of mild hybrid systems is the increased fuel economy offered by the electric motor. This is achieved in several ways, one of which is known as shifting load point. This refers to when the vehicle's computers recognise a load or voltage on the engine and transfer some of that load to the electric motor, saving fuel. This effect is more pronounced during city driving, where stop-and-go traffic can put a continuous strain on the motor. Automakers such as Ram are able to use mild hybrid technology to improve fuel economy in large trucks without sacrificing capacity.

2. Improved Stop-and-Go Functionality

Many new vehicles offer fuel-saving engine start-stop technology. When the vehicle is switched off, for example at a traffic light or stop sign, the engine shuts off to save fuel and restarts when the driver lifts his foot off the brake pedal or touches the accelerator. During this time, the vehicle's electrical functions, such as air conditioning systems, may weaken or switch to a less functional setting until the engine restarts. Mild hybrid systems offer a smoother experience during this period, as the electric motor and battery power the car's systems while the petrol engine is switched off. Restarting is almost imperceptible thanks to the smoothness of the ISG instead of a traditional starter.

3. Weight Reduction

Many hybrid vehicles lose valuable passenger or luggage space to accommodate batteries and related components, but mild hybrids don't suffer as much. Mild hybrids are smaller and lighter than hybrids or plug-in hybrids, giving them an advantage in packaging and vehicle performance. Even when carmakers learn how to deploy batteries in ways that improve handling and weight distribution, lighter weight is almost always better in terms of performance, fuel economy and manoeuvrability.

Who produces Hibride Mild?

The number of new vehicles available with a 48-volt mild hybrid system has grown considerably in recent years. Although the systems are most popular in the United States, their availability is global and extends to many popular makes and models.

• Audi
• Ford
• Hyundai
• Ram
• Jeep
• Mercedes-Benz
• Mercedes-AMG
• Range Rover
• Mazda
• Fiat
• General Motors
• Volvo

Audi and the Technical Challenges of 48V Batteries

Discoveries in the Workshop: The 48V battery is in a low-voltage protected state and will not accept a charge. DTC error code P0A7D00 indicates that the Hybrid/EV battery pack has a low state of charge.

Technical Background: When the 48V battery drops below a set SoC, the protective relays inside the battery open, ensuring that the internal cells remain above the minimum safe voltage limit. The protective relays will not close until the appropriate adaptation channel is set inside the battery.

As long as the 48V battery has an SoC between 5% and 15%, it can be charged manually via the 12V system, following the procedure in the "Service" section. 48V batteries do not need to be replaced, but recharged in such a case. Requests for incorrectly replaced 48V batteries may be refused.

In case of alternator failure, it is necessary to replace the alternator with a new one. After replacement, SVM parameterisation is performed. Depending on the 48V battery discharge, a 12V charging source with a minimum of 50A is required