Voltage drop reading on guage '83 Coupe

[SJ]

> From: "Ben Swann" <benswann at comcast.net>
>
> Is it normal for the voltage reading on guage to read about 1-2V lower
than battery voltage when accessories are turned on, in particular the
climate control fan?    This car registers significantly lower on the
voltmeter than at the battery.
**** Define guage and voltmeter.
Call your handheld voltmeter a  "DMM".
Call the car instrument cluster voltage guage a "gauge".

> Battery reads 12V with engine off.  13.7V +/- .3V varying at idle.
**** Are you reading the DMM at the battery?

> Voltmeter reads: about 11.5 with engine off.  Engine on, no accessories
around 12.3.  When flasher operated, there is a noticable flicker in the
guage needle.  As other accessories are turned on, the flicker becomes more
pronounced.  With lights on, guage reads around 11.5 and when fresh air fan
is on full, down around 10.5.
**** Are you talking about the "guage"? The instrument cluster voltage
guage? If you are, keep in mind that this "guage" is not a precision
instrument. Use your DMM for accuracy.
You can calibrate your DMM low scale using a fresh 1.5 volt battery . . .it
should read 1.65 volts at room temperature.
You can calibrate your DMM higher scale by measuring your car battery. It
should read 12.6 to 12.7 volts when its fully charged.

Now, there is a possibility that there is a voltage drop in the wiring
between the battery and the instrument cluster. You can eliminate this
possibility by using your DMM to check voltages in or around the instrument
cluster.

I suspect that your problem is simply that the instrument cluster guage is
not reading accurately.


> I know this is probably not a significant problem, but is there any good
workaround?
**** If it was me, I would "recalibrate" the guage. One small white paint
dot to indicate where the needle is at 13.7 volts, and one dot to indicate
where the needle is at 12.6 volts. Make sure you apply the dots to show
proper indication from the drivers eye's point of view.

If you are really fussy, get another guage from the junkyard.

By the way, if your car has the climate control system, you can read system
voltage using the climate control.

<snip>

>I am referring to the voltage drop as measured at the voltmeter in the
console with respect to what I read with a VOM at the battery.
**** Always use the same instrument(DMM) when comparing voltages. Otherwise,
you will drive yourself and the rest of us nuts.


SJ
85 Dodge PU, D-250, 318, auto
85 Audi 4k - - sold but still on the road
88 Audi 5kq
90 Audi 100q