[Spridgets] Relays

[derf]

A relay is just an electric switch.  They are usually used to control
big power loads with small switches.  Starter solenoids are relays.
They just use <1amp (usually) and mechanically switch >5amps.
If you are pulling the starter than you are operating a big mechanical
switch for the starter.  A starter solenoid uses a small electric
current to do the same mechanical action as your pulling.
Over time, the mechanical contacts in your headlight switch will
deteriorate and be less efficient.  Those contacts could be used to
switch a relay, and the relay be used in turn to switch the power to
the lights.  Since the relay output contacts are cleaner, newer, and
more efficient, you can get brighter, more reliable lights.  The relay
goes between the battery and the lights.  The control circuit of the
relay draws less power and your light switch will last much longer
switching the very small control circuit power.