batteries, alternators, etc

[Greg Galinsky]

Brett;

Kinf of sounds like the voltage reg. in the alt is OK but the unit may just
be putting out low amps.   My guess is that the unit might be a rebuilt not
a Bosch factory remanufactured unit.

Check what amperage output you are getting.  At 2000 rpm should be at least
35 amps with a slightly discharged battery.   Look at the length of the
brushes in the voltage regulator

Greg
90 90Q
90 80Q
90 80
88 90Q
Miata
----- Original Message -----
From: "Brett Dikeman" <brett at cloud9.net>
To: <quattro at audifans.com>
Sent: Wednesday, January 30, 2002 1:45 PM
Subject: batteries, alternators, etc


> Okay, finally decided to poke around the charging system since I've
> always suspected something isn't quite right.
>
> Off, car not run in several days, battery voltage is 12.5, I believe.
>
> Start it up, voltage at the battery is 14.0 and climbs slowly over
> several minutes to 14.1; dash gauge agrees.
>
> Let it idle for several minutes while I poke around here+there,
> checking for voltage differentials between the terminal+clamp on each
> side, checking the voltage between battery and jumper post.
>
> I had a lot of trouble getting good connections at both terminal and
> ground up front, but voltage up front was -very- close to voltage at
> the battery terminal(s.)
>
> Kick on the accessories; rear window defogger, headlights on high,
> etc.  Engine slows down a teeny bit. Check voltages again.  Much,
> much lower; not much above battery voltage, in fact; 12.8 or 12.9 I
> think; dips occasionally, but probably due to the bad connections
> between test leads+post/ground.  Same at the post, to within less
> than a half tenth of a volt.
>
> Turn the car off, leave headlights on etc; measured voltage drop
> between terminals and clamps, and it's VERY small on the positive
> clamp(we're talking maybe a few tenths of a mV, the Fluke seems to
> have an error range larger than what I measured :), none on the
> ground.  Might clean it up, dunno.
>
>
> This is either a rebuilt or new alternator(don't remember which),
> installed within the last 2, maybe 3, years.  Battery(exide) is at
> least 4 years old and levels were recently checked.  A few white
> specs of battery fluid here+there on top etc.  Terminals looked
> pretty good.
>
> This summer, the alternator seemed to -barely- keep up with the stage
> 2 fan, and once when stage 3 came on(waiting in a parking lot, hot
> summer, AC on) I had to take the car around the block because I was
> afraid the battery would totally give out and/or car would overheat.
>
> Comments?
>
> B
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