The Bosch HD series comprises diverse performance classes and optional variants that can be combined variably. This allows commercial-vehicle manufacturers to find the alternator that perfectly suits to their application. An efficient cooling system and high-quality bearings ensure a high level of reliability. At the top end of the range, there are 28-volt variants with a nominal current of 150 amperes at 6,000 revolutions per minute and an average efficiency of 77 percent (80 percent maximum). The available options include enhanced heat resistance and an extension of service life to as much as 1.2 million kilometers.
Compared with a PWM (pulse-width modulation) interface, the serial LIN (local interconnect network) bus allows more extensive, bi-directional communication between the alternator and the engine management system. As a result, charging voltage can now be adapted variably via a standardized interface, and in this way the service life and availability of the battery improved. In addition, the alternator can be completely switched off – during acceleration, for example. In overrun conditions, by contrast, its performance potential is exploited to the full. Depending on overall concept, this can reduce the fuel consumption of a heavy truck by as much as one percent – a cost factor which cannot be underestimated in commercial vehicles with high mileage. Moreover, a LIN allows as many as four parallel alternators to be synchronized in an on-board network – an option that is especially used in buses. For the electrical connections, a proven 5-pin connector is used.