Re: adding relays to euro lights

["Rossato, Bob HSD" <ROSSATR@hsd.utc.com>]

When I wired a quad 5 3/4 " setup I ended up using 3 relays.  One for
each pair of filaments.  If I remember correctly a 55W bulb will draw
4.3 amps and a 100W will draw 7.6 amps, or thereabouts.  If you end up
using 55/100W H4's and 100W H1's on your 4x6 setup, and only use one
relay for the high beams, then you will draw 30.4 amps.  Most relays are
rated for only 25-30 amps, though I've heard of some 70 amp Bosch relays
but I'm sure they're a lot more expensive than two 30 amp relays.  Of
course if you stick to 55/60W H4's and 55W H1's you can use two relays
only, but you're stuck if you want to upgrade in the future.

Wiring:

1) Pop the wires from the headlight sockets (use a jewelers screwdriver
to reach into the socket and press down on the locking tab) and cut off
the terminal.  This will give you the most usable wire.

2) Run this wire to the trip circuit of the relay.

3) Use 10-12 gauge wire from the battery to the relay and from the relay
to the headlight.  Be aware that the tabs on the headlight bulbs are not
your standard .250" width.  They are .312" wide.  I got the proper
terminals from AMP.  Though apparently Huw Powell has had luck in
jamming the .250's on.  You should probably beef up your ground wires
too.

4) Very important.  Install in line fuses to each of the 3 wires going
to the battery as close to the battery as possible.

5) I used relays that had 2 output terminals.  Much easier than trying
to crimp two 10 gauge wires on one terminal.

6) Location of the relay is more a matter of mounting convenience.  The
key is to end up with the shortest run possible from the battery to the
headlights.  Whether the relays are closer to the headlights than the
battery is irrelevant since the total length of wire is still the same.

7) As for mounting hardware for the relays, I used the plastic relay
mounts that clip to the top of some of the vw/audi fuse panels.  The
Scirocco II uses a metal bracket mounted next to the radiator that holds
one of these plastic relay mounts.  I got one of those and then clipped
the 3 plastic holders end to end and mounted them on the metal bracket.
As an alternative, if I remember correctly there are 3 relays mounted
side by side under the passenger side of the dash on the Audi coupes.
That might actually be a better arrangement as the relays are
cantilevered out the way I did it.  I might give that a try next time.

Well that's the way I did it anyway.  HTH

Bob


From: Dan Simoes <dans@ans.net>

>>>This is a relatively simple task, once you know how the relays
are wired.  I plan to use two relays, one for high beams and one
for low beams.  Should I use more?
The question is... there are wires from the headlights that go
through the fuse box and then to the switch.  What is the
best place to intercept the wire so that the signal goes
from the switch to the fuse to the relay, then to the light?
Should I wire the relays close to the headlight?
Should I just discard the existing wiring?

I'm hoping that my existing electrical problem (lights, power
cut out at random but always with lights on) is somehow related
to the lights and that adding relays will fix the problem.

I'd especially like to hear from anyone who has wired relays on a
car using the quad 4x6 euro light setup (ie urQ or 84 4000/80q)

| Dan |<<<