Left: Bosch generator (old version, back view):
1 - B + connection (to the battery);
2 - 0+ connection (to the battery charge indicator);
3 - voltage regulator;
4 - noise suppression capacitor.
Right: Bosch generator of the new generation can be recognized by the cover (1). Position (2) shows the B+ cable to the battery.
When the ignition is switched on, voltage is applied to terminal 15. The alternator, however, is not yet running and therefore the unpowered D+ contact acts as «minus». The indicator flashes because there is a potential difference between the on-board network, which is powered by the battery, and the idle generator.
If the engine is started and the generator has reached the required speed for charging, the voltage regulator connects it to the on-board network. Power is now supplied from terminal 15 and additionally from terminal D+. When there is no potential difference, the charge indicator goes out.
When the ignition is switched on, the lit charge indicator should «pre-excite» generator. Only in this case, the generator will be able to produce current already at low speeds. However, pre-excitation is only necessary when the generator is first started.
Visitor comments