Well, using a relay with your driving lights prevents all the current from
going through your switch. Headlamps and hi-powered driving lights draw
quite abit more amperage than the switch is intended to hold.

Your switch wiring contains enough resistance that it would quickly heat up
and perhaps melt the switch, possibly causing a short, so your switch
activates the relay which carries the load to the lights.

If you'd like to test this theory, try direct wiring the lights through a
simple on/off switch and let them stay on for awhile (take my advice, the
switch will get real HOT--personal experience).

I can't remember what the dual battery relay is for, probably to prevent
drain...but it's getting late and I've been sleep deprived for weeks as it
is,...so off to bed I go.

Good Luck.

Doug
Almost a vanagon owner, but not quite yet.
I do have 3 '74 SuperBeetles at present to feed my habit.

----- Original Message -----
From: "Mervyn Readman" <Themervino@CS.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Thursday, November 08, 2001 9:00 PM
Subject: Why we need relays

> I bought the Hella XL auxiliary dim lights and was wondering what is the
real
> purpose of the relay and why it can't be straight wired to the regular dim
> lights and also with the dual battery is the relay simply to stop the
starter
> battery from draining when the auxiliary  becomes empty
>      Merv
>      90 carat in the sunny south
>