Quote:
Originally Posted by mrr23
the exciter in the alternator is what does it. once it reaches rpm speed it sends the signal to the computer. been there, done it. the reman alternator i got had a test sheet showing output testing and showed when it excited. sure enough it wouldn't not turn on until i hit 2200 rpms. kept getting the charging system fault on the dash. so had mine rebuilt and gave theirs back.
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Well, I don't think I have hit up against that particular problem. At least not yet. I have had at least three alternators in the C5Z since I bought it, and never got that sort of error message. Since the car will cruise on the highway in 6th gear well below 2200 rpms, I would think the battery would gradually discharge and such an error fault would manifest itself. Just cruising down route 95 at the speed limit would be well under 2200 rpms, so if the alternator is not charging the battery the entire time, I would imagine the battery would go dead in pretty short order that way. Heck, I would imagine that most of my driving is actually below 2200 rpm.
Wouldn't this show up on the ammeter while driving? When my current alternator was working OK, it would normally show 14 volts regardless of what speed the engine was running. Even at idle just sitting in the garage. Wouldn't that be telling me that the alternator was pumping juice to the battery regardless of engine speed?
Now you have me interested in looking into how this actually works. I would have thought the circuitry would monitor the battery voltage, regardless of engine speed, and spark up the alternator when electrical demands needed the juice. Sort of how a trickle charger works.
But I am guessing that there has to be some lower limit in the speed the alternator is spinning when it cannot deliver the amps necessary. Which then brings up the question as to whether a higher amperage rated alternator would be able to deliver that lower limit amperage at a lower rpm speed than a lower rated alternator. For instance a 145 amp alternator could deliver, say 50 amps at 1200 rpm (just pulling numbers out of my hat) whereas a 110 amp alternator might need 1600 rpm to deliver the same amperage. Honestly, I have no idea. Might be the complete reverse.
