Voltage drop reading on guage '83 Coupe

[SJ]

From: "Ben Swann" <benswann at comcast.net>


> I tried to be clear, guess I wasn't.  All readings taken at the battery
were
> with a Digital Multimeter.  The readings from inside the car were all
> referring to what was read on the factory guage,  guess I should not have
> referred to it as a voltmeter.
> Basically there is a difference in voltage between what I read at the
> battery with DMM vs. what the guage installed in the guage cluster reports
> from where it is wired.
**** If the gauge reads different than the DMM . .. with engine not running
and no accessories on . . .then the gauge is reading wrong. You can verify
this by using the DMM and read the Cigar lighter voltage, or the glovebox
lamp voltage.
When you have no accessories on, you have no current flow, no current flow
means no voltage drop in the wiriing. Therefore the guage will be reading
battery voltage. And, if it is not indicating 12.6 V, then the guage is off.

>
> I'm not trying to drive folks nuts, just trying to see if others who have
> '82-83(perhaps later years) experience this apparent voltage drop.  Does
> your "guage' needle flicker when accesories are turned on and off?
**** As stated above, I doubt that you have "an apparent voltage drop". Your
gauge is reading wrong.
Yes, the guage will flicker when you turn accessories on and off. Just like
your house lights may flicker when some big assed A/C unit in the house
kicks in.

>
> BTW, what should DMM read when engine running and no other accessories.
Is
> 13.7 sufficient to indicate charging satisfactorily, or should it be
higher?
**** Typical weak audi electrical system, but this is a common reading on
audi's. 14.3 volts would be nicer, but 13.7 is ok for a fully charged
battery. Everything is normal.


> I basically am trying to determine if there is a problem with the car
other
> than that's just the way it operates as originally wired.
**** Nothing wrong. But, since you depend on the guage to tell you if you
have any problems cropping up, I would put those small paint dots to
indicate normal battery conditions. The meter movement is ok, it will always
be at the same place for the same voltage . . .you just cant rely on the
guage numbers . .thats why you use the paint dots . . . cause in a few days
. . . . you will forget the correlation between DMM and guage numbers. BTDT

SJ