Date:         Sun, 4 Jan 2004 13:42:04 -0800
Reply-To:     Ryan Press <ryan@PRESSLAB.US>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Ryan Press <ryan@PRESSLAB.US>
Subject:      Re: [Syncro] Headlight relay upgrade?
Content-Type: text/plain;charset=iso-8859-1

Steve Delanty said:
> George wrote:
>
>>Considering the short run of wires and the minor currents involved this
>> is
>>surely wasted effort.  I have, arguably, one of the best portable DVM's
made and
>>I doubt if it could reliably measure the small potential drop at full
>> load
>>across even the longest conductor used in the headlight system.
>
>
> Hmmm. My American Electricians Handbook shows the DC resistance of 14AWG
stranded copper wire to be .002624 ohm per foot.
>
> 5 feet would be .01312 ohm. (I imagine there's more than 5 feet...)
>
> At 10 amps, the voltage drop is 0.1312 volts.
>
> What meter do you have that won't measure 1/10 of a volt accurately?
>
> Did you get it at Harbor Freight?
>
>
> Steve
> EJ22 -> '86 Westy "Escape Pod"

I'd say the wiring has a substantial voltage drop; those numbers above
seem reasonable to me.  Also the old headlight switch (and all those
connections!) could have even more.  If you were to look at the PDF file
below it shows that running at 90% voltage gives you 80% of the light and
300% life.  So you do get SOMETHING running the lower voltage; more life.

<http://www.walamp.com/Product_Pdfs/isl297b.pdf>

On my 2000 GTI, the low beams are daytime running lamps with the headlamp
switch off.  They seemingly use a 0.5mm wire that snakes into the loom and
comes back out again to drop a little voltage.  I'm not sure how long this
wire is, but it has about a volt of drop.  By calculation alone it would
be about 4.5 feet.  That sounds reasonable.  So the daytime lamps would be
about 85% as bright but last 275% longer in this mode.

US automotive headlamps have a "Test Voltage" of 12.8V according to FMVSS
No. 108.  So the designer of the bulb is expecting a 0.7V drop from the
alternator to the headlamp, assuming a 13.5V alternator output.

<http://fmvss108.tripod.com/fmvss108text.htm>

In Europe the test voltage is 13.2V according to ECE R37.

These standards may not have been in effect when the Vanagon was produced
but I'm sure new bulbs will use these guidelines.

So I think the ideal thing to do would be to upgrade the lighting system
(wiring & relay) to provide 12.8V at the headlamps.  This will optimize
light output as well as bulb life.  Perhaps our Vanagons are already
capable of doing this?  Do the European Vanagons have larger wiring to
satisfy the 13.2V?  I hadn't thought of this before.

I use Philips Vision Plus bulbs for high beam on the GTI; it has HID low
beam now.  ACH!  THE HORROR!  They are E-code lamps which are MUCH better
than the DOT HID lamps we have here.  Have you seen the glare from a Honda
S2000?  Terrible!

<http://www.eur.lighting.philips.com/int_en/prof/about/press/automotive/resultsVision.html>

Philips does not offer Vision Plus in a 9004, although they do offer the
Premium series which is supposedly pretty good.  I have not tried these
yet.  For starters, I have found that a good cleaning of the lenses inside
and out has a profound effect!

Ryan