http://www.dimebank.com/Light-up.html

I used Doug's schematic four years ago when I installed a set of Wipac Quadoptic lamps.  I've modified the drawing by adding some color to it. 

 My copy can be found here: 

http://s193.photobucket.com/albums/z130/americanbam96/Diagrams/?action=view&current=Relay_Panel_modified_DKLawson_kopi-.jpg 

http://www.ausmini.com/forums/viewtopic.php?t=11529

QS, I'm sure I have a schematic somewhere at home but I couldn't find it last night.

Advance Auto Wire is going out of business following the death of their owner.  Until further notice, the family is keeping the web site up as a technical resource.  There is an excellent schematic of the headlight relay circuit there.

Please visit:
http://www.advanceautowire.com/
and on the home page, look down the left side of the screen and click on the link for "Headlight Relay Kit".  There is a schematic there showing you what to do. 

"To Power Source" would be the hot terminal on the solenoid.  The relay terminal numbers are for the standard 30A ISO/Bosch type relay.  The wire colors shown correspond to the standard Lucas scheme for the headlight wiring.

Doug L.

Even so, the toggle switches are expensive and the relays are cheap insurance.  Again, an additional benefit reported by many (depending on the condition of their car's wiring and switch contacts) is that even standard headlights appear brighter when the relays are added.

QS, while I look, you may want to visit the Victoria British web site and look up part number 10-679.  That's a headlight relay kit for $30.  It's not on a panel but it has everything you need to add two ISO/Bosch relays to the headlight circuit of LBCs.  I don't believe our host sells anything close so they shouldn't mind the referral.  Until recently you could buy a sophisticated relay kit from AdvanceAutoWire.com.  They recently had a death in the family and were closing down operations last month.

Doug L.

Metric is for people who can't do fractions.

Alex, you wont' get an argument from me. Power is power, current is current.  However, cheap switches that are marginal remain cheap switches that are marginal.  The relays take virtually all the load off the dash switches.  It takes some time to make and install the panel but once it's there you have switches with virtually infinite life and relays that are universally available, cheap, and easy to replace should they ever fail.

QS, I'll see what I can find.

Doug L.

55w is 55w regardless of whether it goes through a halogen bulb, a sealed beam or a foghorn...

Metric is for people who can't do fractions.

I'm solidly in Mur's camp.  The switches aren't really up to the task of the higher current of the halogens and replacement switches are expensive.  Making or buying a relay panel will protect the dash wiring and switches and in most cases improves the brightness of the lamps... even if they are traditional, non-halogen, sealed beams.

By adding an additional momentary contact pushbutton to a relay circuit you can also add a headlight flasher function to older cars like mine that have no provisions for it.

Doug L.

"I don't know much, but what I do know I know little of "

If you're going to upgrade lights (here in the land of the giant grasshopper I have 2x100 watt headlights + 2x100 watt spots) then relays are a good idea; both to protect old switches etc and to provide as much power to the bulbs as possible.

Cheers, Ian

I think the switches from mk III onwards just can't properly power a regular halogen light for any length of time.  A pair of relays protects the headlamps switch and the dimmer switch, provides full voltage to the headlamps and they in turn work better and have the full service life that can be expected of them.

So do it. 

Metric is for people who can't do fractions.

is this any help?

Many moons ago we discussed the benefits fo adding relays to the headlight. A member (I forgot the suspect) actually did this and I think offered it as a kit for others.

Whom might this be?