RE: Relays

["A. Bjorkheim" <andreb@u.washington.edu>]

> Thanks Andre, this makes perfect sense.  So I would have one wire coming 
> from the fusebox into the relay.  I will also have another wire coming from 
> the battery into the relay.  Then I will have one wire coming from the 
> relay to the headlight.  Is this correct?  If it is this easy, where can I 
> purchase such a relay for this type of use.
> 
     Precisely.  Most relays are either 4 prong or 5 prong (More about
the 5 prong later). The terminals are as follows:

	30 - Goes to + on Battery, should be higher gauge than stock
        85 - Goes to Ground or - terminal on Battery
        86 - Trigger of relay, usually original headlight wire
        87 - New headlight wire, should be higher gauge than stock

     I cant say all relays will have those terminal numbers but they
should have at least these 4 types of terminals.  The way it works is
that the original headlight wire is now not going to the headlight but
is the trigger for the relay.  Once you turn on your headlights the relay
senses the voltage at the trigger wire and then turns on, taking power
directly from Terminal 30 onto Terminal 87 and from there to the
headlight.  Now rather than having 10 or 12 feet of old crappy 16 gauge
stock wiring, you can have 2 or 3 feet of 12 or 10 gauge wiring.  Once
you turn off the headlights the trigger is now off and so it cuts the 
current flow through Terminal 30 onto Terminal 87.  
     On some relays then come with a 5th Terminal, sometimes called 86a or
86b.  I believe these work opposite to the general case of most relays.
These terminals sense when there is no voltage at the trigger, then they
turn on.  Once you make the trigger wire hot, the relay turns off.  I 
havent tried it or wired anything on my car in this fashion so I can only
say that I have heard of people who have done it.  If you want precise
details on how I wired mine, just let me know and I will type it out for
you in detail.  It will prolly take me a half hour or so to get it all
out there.  BTW, dont forget that if you upgrade the power wires for
your lights and you use higher wattage bulbs, you should upgrade the
lights ground wires as well.  Best of luck.  Oh, as to where to find them,
up in the Seattle area I found my relays at a place called Al's Auto
Supply, but most descent Auto Parts Stores should carry relays of one
form or another.

  Andre'
  480Watts of Headlight power at HighBeam  =)  Soon to be 560Watts...

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