<VV> Re: Alternator (not) charging question

[djtcz@comcast.net]

Subject: <VV> Alternator Charging Question

>snip<
>Our alternator is not charging the battery properly on our '66.  We put a
>brand new Delco voltage regulator on.  When the car is running, the voltage
>is 12.65 at 2000 rpm with no headlights or accessories (radio) running.
>With headlights or accessories on, it goes down to 11.96.
>Is this sufficient to power the car, do we need a rebuild, or is something
>else wrong?
Why did you change the regulator?  To "fix" a non-charging concern?
Radio Shack sold a $5 tester that plugged in the lighter. Red, yellow, and green lights to indicate approximate charging voltage, useful while driving.
The factory manual outlines a series of tests, but warns, as Joe did, that the battery needs to be somewhat charged before a good alternator/regulator can get it over 12 volts.  State of charge can Be determined with one of those floating ball syringe devices.  It seems to me on cars that will start on their own the voltage is over 13.x within a minute if everything is OK. Another of the manual's SEVERAL tests, and seveal items along in the process, is applying battery voltage to the F (field) terminal.  That will order the (spinning)alternator to crank out max output.  Start with low revs, because the voltage can get dangerously high when unregulated.  If there is 13.5 volt output or more @ 1500 rpm or so with lights, heater fan etc, on, then the alternator is OK, and regulator or reg circuit is bad.
Having a separate alternator/regulator can be a good thing.  My wife's 2001 Mazda MPV needed a $600 alternator job last week 200 miles from home. (The internet reports that may be one of the few troublespots in an otherwise fairly rugged car). The local alternator shop and the local dealer both said those integrated alternators are not being rebuilt successfully.  As it was a charging issue, not a noisy bearing issue,  one possibility is the regulator cicuitry was bad. My 87 Volvo with 240,000 miles has its original alternator, and 3rd internal0but-replaceable regulator/brush assembly.