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Re: Lighting questions
For the £45 BRM in the UK charge for their complete upgraded wiring
harness - straight off alternator I think - its not worth arguing about
IMHO. I now run 180w / 460w dip/main in total, and as in the song 'I can see
clearly now the day has dawned' every time I light up.
UK Urq
-----Original Message-----
From: Robert Myers <rmyers@inetone.net>
To: scott miller <macatawa@hotmail.com>
Cc: Quattro list <quattro@coimbra.ans.net>
Date: 07 August 1998 19:36
Subject: Re: Lighting questions
>At 09:31 AM 8/7/98 PDT, you wrote:
>>>
>>>Scott, IME, stock wiring is simply not heavy enough to carry such loads
>>for
>>>any length of time
>>
>>Why?
>
>I've BTDT. I inserted higher wattage bulbs in the fog lights of an '88
>90q. Shortly thereafter I had no fog lights due to burnt out wires or a
>connector somewhere. I never resolved which. My wife totalled the car
>shortly after the fog lights died. New light bulbs did not solve the
>problem. Calculations be damned. The wiring (including/or the various
>connectors?) simply ain't up to the job.
>
>>I've followed threads endlessly, downloaded proposed wiring
>>diagrams from other sites, but never seen an analysis of stock wiring.
>>My high beams are powered from the wimpy switch by one 12 Ga. wire, then
>>two fuses feed two 14 Ga. wires that go to the bulbs, then two 14 Ga.
>>wires to ground. I'm on the road and can't look this up, but I believe
>>14 Ga. wires are rated for 15 amp applications (?).
>
>Could be. 15 amps at 12 volts = 180 watts - MAXIMUM. A 100 watts lamp at
>12 volts draws 8.3 amps or nearly 60% of the rated maximum load for the
>wire. Now, throw in a resistive connection or two and some IR drop in the
>wire itself and the heat produced by current flowing through that
>resistance and the next thing you know insulation is melting.
>
>How many have tried these plug-in high wattage 9004 lights? I have on one
>of my '89 200tqs. They kept burning up bulb sockets at the ground
>connection. It was so bad that I went back to stock and then added fog and
>driving lights. (Incidentally, these were the sockets supplied by
>Competition Unlimited, not stock Audi sockets. They were significantly
>longer lasting than the stock sockets.) Slightly resistive connection +
>current --> HEAT. (Watts = I^2*R.) This localized heat will definitely
>burn stuff up. Again, BTDT.
>
>>That's about 200
>>watts at normal alternator voltage per wire, plus an unknown safety
>>factor (usually pretty high for automotive). That rating also takes
>>into account momentary spikes. Hella cites up to ten times the power
>>rating for their bulbs on start up, other applications may draw even
>>more, and the wires are rated for those normal applications. What about
>>the connections? These same connectors are used for much higher loads
>>elsewhere. I agree there are line losses, after ten feet of wire you
>>should jump to the next Ga. wire, and I'm close to ten feet. My bulbs
>>may run a little cooler and last a lot longer.
>
>And produce less light.
>
>>How much difference does heavier wiring make in headlight performance?
>
>You do the calculations. If there is enough IR drop in the wiring before
>(or after for that matter) the light then the current through the filament
>will be decreased and light output (rather closely proportional to I^2*R)
>will decrease in correlation. 13.4 volts, at the light, will be
>significantly brighter than 12.0 volts. The difference between 13.4 volts
>and 8 volts will be even more pronounced.
>
>>No one has cited any measurements, just subjective opinions.
>
>I recall a number of posts which reported measured voltages at the light
>socket. These measurements have been done, I think. No, not by me.
>
>>I spent a
>>lot of years making automotive and electronic optics, I saw a lot of
>>production and maintenance workers try to fix problems with the product,
>>and convince themselves they saw an improvement without measuring it.
>>It's easy to do, I've done it. I usually got called by QC at 2:00am to
>>resolve the problem and help throw away several hours of bad product.
>>What's a small increase in headlight brightness worth? In low-vis, poor
>>optics will throw even more blinding light where you don't need it and
>>make your fog lights even less helpful. If you have good optics, you
>>don't need an incremental increase in brightness.
>
>Agreed, good optics help greatly. The lights in my S6 are almost
>infinitely superior to my '89 200tq. Optics makes the difference.
>
>The desirability of incremental increase is, of course a matter of opinion.
> If you spend your entire life driving only during the daytime you don't
>need lights at all, much less an incremental improvement. If you drive
>only on well lighted city streets you almost don't need lights. If you
>drive on totally dark country roads, every little bit of extra light you
>can get is a help. Especially as you age and your night vision begins to
>suffer age related deterioration. BTDT, also. :-(
>
>Am I satisfied with the lighting on the S6? Well, it's certainly much
>better than those on the 200. Enough so that I can probably live with them
>for a while. Until, that is, I can find a good way of mounting some good
>100 or 130 or 180 watt fog lights and driving lights in an unobtrusive
spot.
>
>>I'm not an EE, I really don't understand electrons as well as I should.
>>I appreciate the dire warnings and many other tips, and I'll appreciate
>>anyone telling me why I'm wrong and saving me a whole lot of trouble and
>>$. Luckily I usually wear nomex for my 400 mile weekly commute, maybe I
>>need to move my fire extinguisher out of the trunk?
>
>No flames, Scott. You are certainly free to do whatever you want. It's
>your car. I was simply trying to relate my experiences. I wish you
>success with your lighting mods.
>
>>Scott
>>'90 200tqw
>
>
>___
> Bob
>*******************************************************************
>* Robert L. Myers rmyers@inetone.net Home 304-574-2372/1166 *
>* Rt. 4, Box 57, Fayetteville, WV 25840 USA WV tag Q SHIP *
>* '95 S6 Cashmere Grey *
>*******************************************************************
>