Hi,
My 740 (1990) stalled after an hour of driving (mostly idling) in Manhattan with lights, AC, stereo on. The battery was so dead that iJust changed a voltage regulator, but idling with lights on etc. still produces dead battery. Checked the alternator- at 3000 and more rpms output 15V, sometimes even more than 16V. My understannding that it should be no more than 14,6V. When idling it is something like 13 or so. No big drain between the alternator and the battery. With lights and AC on volta(e at battery drops to 12.6 or slightly less, like 12.4. Battery itself is 12.6, when the engine is not running.
Question- since I just changed voltage regulator, is there a way to install it improperly. The brushes seem to work, there would be no current otherwise. I did not disconnect battery when changing voltage regulator, could I have shortcutted it in some way? Also, there is a tiny black box (could be a relay) next to the voltage regulator on back of alternator. It is connected to the output screw of the alternator and attached to the alternator surface without other wisible wiring. What's that? Can it also be some kind of regulator? I could not find reference to the part in any internet sources and had no opportunity yet to get my hands on a VOLVO book.
Does anyone have any experience with this stuff?
Andris