RE: Hooking up euro lights.

["L. M. Lloyd" <ubik@austin.rr.com>]

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> --- "L. M. Lloyd" <ubik@austin.rr.com> wrote:
> > > Why all the relays? I am probably missing something,
> > but I don't understand what purpose all the relays 
> > serve.
> 
> You don't need as many as the instructions show. If
> you read all of it you will see that he used extra in
> case one went bad he wouldn't loose two lights from
> one relay. You also don't need to use 40amp relays, I
> used 30amp and am quite happy with the results.
> 

I did read it all, and I realized that I did not need all 6, I just
was wondering if I needed any?


> > So, what am I missing? it seems strange to me to use
> 
> > a switched 12V signal, just to switch another 12V
> > signal. 
> 
> Because you're using a switched signal from a small
> gauge wire to trigger the relay with preferably a much
> larger gauge wire to feed more juice to the bulbs.
> 

OK, doing tests today with the car running, I have a pretty
consistent 13.05V straight off the battery, and a rock solid 11.92V
off the wiring harness at the headlight connector. So, if I am
understanding the comments made, and the supplemental pages included,
the halogen lights used in the Euro headlights need a minimum of
13.5V to operate at 100%, and at 13.05V will operate at around 97%.
However, at 11.92V they will only operate at about 60%. All of this
seems like a very good reason to look into the possibility of
converting H4s into Xenon lights, but that is for some other day. So
the real purpose of the setup shown on scirocco.org is to upgrade the
light wiring harness to carry a more direct voltage from the battery,
to get as close as possible to a 13.5V signal to the lights. Got it.


> > Why not just use the original signal/wire? 
> > It seems a lot easier to just rewire the connector,
> 
> You can do that if you don't mind having lower output
> lights.
> 

As I now understand that the lights need (optimally) 13.5V, this now
makes sense. I had previously thought that the lights would have been
designed with a 12V system in mind, so the difference between 12V,
and 11.92V did not seem worth wiring a new system.


> > rather than ripping out the old wires, 
> 
> Who said you have to rip out the old wire?
>  

Well, if you are going to do it, might as well do it right! I
wouldn't want to leave in wires that I am not going to be using.

> > finding a place to mount the new relays, 
> 
> See my install, no problems with finding a place to
> put even six relays:
> http://photos.yahoo.com/bc/scirocco16v_1986/lst?.dir=/VW+Stuff&.view
> =t  
> 

Personally, I don't like the idea of a non weatherproofed electric
component in the engine compartment, especial given how often we have
flash floods around where I live. A weatherproofed enclosure could
certainly be made, but that adds size, and further complicates
mounting.


> > I hate electro-mechanical relays (they just seem so
> > WWII)
> 
> As far as I know they're used in all vehicles to date.
> 

I have no doubt of that, I am not aware of any cars that use circuit
breakers either, but that doesn't mean that I would choose a fuse
over a circuit breaker given the choice. It is just that I come from
more of a computer/electronics geek background, so electro-mechanical
relays seem very, well, quaint. I am not arguing their effectiveness,
it is just when you are use to dealing with surface mount
transistors, a coil with a plate and a spring seems very stone-aged


> > That was when it occurred to me that perhaps
> > electro-mechanical relays had some property or
> > benefit I was not taking into account. 
> 
> Amperage!
> 

Now you lost me again. As I understand it, a relay can limit the
amount of amperage in a circuit, but it can't add to the amperage in
a circuit. Perhaps I got this wrong, but it seemed from the comments
made that what was at issue here was voltage, not the amperage in the
line, so I am unclear on what this comment means.

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