Reconditioned Audi Mild Hybrid Alternator

The Audi/VAG code 4N0903028F identifies a 48 V starter-generator for a mild hybrid system, referred to by Audi as the Belt Alternator Starter (BAS).

The component is driven by the accessory belt and combines the functions of generator and starter motor for the MHEV system. It should not be considered a conventional 12 V alternator, as it operates on the 48 V electrical network and interfaces with the MHEV battery, the DC/DC converter, the engine control unit and the vehicle's energy management. It is used on Audi models with a 48 V mild hybrid architecture, particularly on higher-segment platforms with V6 petrol and diesel engines.

Technical specifications

• Nominal voltage: 48 V.
• Nominal current: 250 A.
• Type: belt-driven starter-generator for mild hybrid system.
• Original equipment supplier: Continental (later Vitesco Technologies).
• Liquid-cooled.
• Torque transmission via Poly-V belt.
• 6-rib pulley.
• Internal power electronics.

DIPA can service these components thanks to its experience and expertise.

Functions

• Generates electrical energy for the 48 V mild hybrid on-board system.
• Recovers energy during deceleration and braking, contributing to recharging the 48 V battery.
• Restarts the internal combustion engine in Start&Stop strategies.
• Enables faster and less perceptible engine starts compared to traditional Start&Stop systems.
• Works with the DC/DC converter to supply the 12 V electrical network.
• Regulates generated power according to the vehicle's energy demand and the state of the 48 V system.

Model applications

• AUDI A4/A5/A6/A7/A8/Q5/Q7/Q8

Common faults

• Irregular starts and/or failure of Start&Stop operation,
• Error messages related to the mild-hybrid system,
• Reduced energy recovery capacity during deceleration.

Final conclusions

The Audi/VAG code 4N0903028F identifies a 48 V MHEV starter-generator with a nominal current of 250 A, liquid cooling and belt drive via the accessory belt. The component participates in power generation, energy recuperation, Start&Stop functions and the management of the mild hybrid electrical network.

DIPA offers a wide range of automotive spare parts: from original equipment parts to aftermarket items selected from the best manufacturers on the market. Additionally, it supplies remanufactured components that perform like new, offering cost savings on replacements and contributing to environmental protection through the circular economy. If the part you need is not available, DIPA can remanufacture your unit on demand, restoring full functionality and safety in a short time.