[s-cars] Need Electrical Help

[Tom Green]

What's really peculiar is charlie at elektro needs electrical help.  
Now, you have said either headlights or a/c and the fan that 
accompanies it drops the voltage.  Because, if it were only the a/c and 
fan I would have you out there checking that fan motor for heat.  They 
have been know to go exponential on current draw when the bearings 
fail, with very messy consequences.  I would suggest reading the 
voltage at the jumper post under the hood while this drawdown is taking 
place.  Check if it cranks as fast after the apparent voltage drop.   
Clean the battery cable connections and ensure they are tight under the 
hood also.   Check the positive cable for corrosion, perhaps extending 
under the insulation sheath.   If all is fine here, start with the 
alternator/voltage regulator connections, pointing toward a replacement 
regulator at least.  That's all I can do from here, Charlie.    HTH

Tom '95 S6

On Aug 21, 2004, at 19:08 Charlie Smith,  <charlie at elektro.cmhnet.org> 
wrote:
>
> Subject: [s-cars] Need Electrical Help
> To: s-car-list at audifans.com (Audi S Car List)
> Cc: Charlie Smith <charlie at elektro.cmhnet.org>
> Message-ID: <200408212308.i7LN81Fo000169 at elektro.cmhnet.org>
> Content-Type: text/plain; charset=us-ascii
>
>
> I've got a peculiar situation, that I think is caused by a high
> resistance connection somewhere.  The question is WHERE?
>
> The symptoms -
>
> The engine cranks fast and starts fine.  On first starting, the S6
> voltmeter reads about 14 Volts, as I'd expect.  This tapers down to
> maybe 13 Volts after running a couple of minutes.
>
> When I put a load on the electrical system, the voltmeter's reading
> drops down a volt or two.  A load like turning on the headlights,
> or when a relay related to the A/C clicks under the dash ... my guess
> it's for the compressor clutch or the radiator fan.  Either is enough
> to knock the bottom out of the voltmeter's reading ... sometimes below
> 12 volts.
>
> Any suggestions on where I should start looking?  I know, first put a
> voltmeter across the battery and see what it reads while the voltmeter
> in the dash is pulling it's stunts.  My bet is the battery voltage is
> stable, given how well the engine cranks while starting.
>
>     - Charlie