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Fw: Lighting questions
-----Original Message-----
From: DRoxburgh <DRoxburgh@email.msn.com>
To: scott miller <macatawa@hotmail.com>; Robert Myers <rmyers@inetone.net>
Cc: Quattro list <quattro@coimbra.ans.net>
Date: 07 August 1998 23:03
Subject: 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 *
>>*******************************************************************
>>
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