Not So Ur q Questions

[quk@sievers.com (Phil Payne)]

In message <199612020809.DAA24190@hammurabi.nh.ultra.net> human writes:

> I liked the underhood fuse box on my 83 5kt, you could get to both sides
> of it to work and you didn't have to kneel in the slush to look at it on
> the roadside.

Get yourself an urq.  You get both.

> I will, however, definitely be upgrading the lousy 8 (if that!)
> gauge wires between the alternator, the fuse panel, and the battery, to
> something more substantial.  The main reason for observed voltage
> fluctuations at the console voltmeter in my car is series resistance, not
> operating voltage.  My 100 watt high beams running off the alternator prove
> that.  Hmmm, the rear window defroster is also another major candidate for
> rewiring, both +12 and ground.  Turning it on trashes my radio reception!

Series resistance also defeats the capacitor installed to suppress interference 
from the alternator.  It's not uncommon to find resistances becoming higher in 
old auto wiring, partly because the grain structure in the cable changes slowly 
over time.  Copper wire is hard when first drawn down to size, and is annealed 
to soften it for "flexible" applications like auto wiring.  This process also 
reduces its electrical resistance.  Over time, carrying current, the annealing 
process reverses.  If the wiring gets hot frequently (often the case in Audis) 
the process is accelerated.
 
I find _many_ of the circuits on my urq are under-specified.  Especially the 
rear wiper, which is fused for 25 amps and can pull 15 amps when stalled (e.g., 
with the blade frozen to the screen) but is wired with 1mm wire. 

(As an aside - always make sure the wipers park properly in winter.  If they 
 freeze in the parked position, trying to start them obviously fails and you 
 then go and free them.  The motor is only pulsed by your attempt, but the 
 stall current is switched off when you switch off the wipers.  If they're 
 frozen but _not_ in the parked position, the motor itself contains a parking 
 switch that will keep current flowing all the while the ignition is switched 
 on.  The motor and wiring can get mighty warm while you're walking round the 
 car.)  

--
 Phil Payne
 phil@sievers.com
 Committee Member, UK Audi [ur-]quattro Owners Club