Luxury passenger cars such as the new Audi A8 offer their driver and passengers a multitude of comfort and safety systems, such as air suspension, heated front windscreen and heated seats. The trouble is these use several hundred Watts of energy each and, added together, they create such high energy demands that the car’s alternator cannot always cope with it. To overcome this problem, the new A8 incorporates an innovation called Electronic Battery Management (EBM), developed by Bosch.
EBM controls the whole electrical economy of the vehicle, from generation by the alternator to storage in the battery to use by the various systems. It serves to guarantee optimal energy supply throughout the vehicle’s essential systems, whether it is in motion or at rest.
The functions of the system can be divided into three main groups: battery diagnosis, dynamic energy management and idle state management.
Battery diagnosis assesses the level of charge of the battery. Dynamic energy management ensures that as much electrical energy as possible is produced and distributed in the best possible way. For example, if necessary, the system can progressively reduce the output of the heating system so as to lower peak demand and yet still provide warmth. It also makes sure that power supply from the alternator and demands from energy consumers match the state of the battery, particularly at start-up or when the engine is under extreme pressure.
If the vehicle has been left standing for a long time and the battery has become excessively discharged, the idle state management system kicks in. It regulates the supply of energy to those components, which are still active even when the vehicle is at rest.
A major advantage of EBM is that, by ensuring that vehicles are always supplied with a secure source of electrical energy, it allows development of innovations such as Start/Stop, which reduces emissions by switching off the engine when it comes to a halt and automatically starting it again when the accelerator is pressed.Published 15 March 2003