Question

[Ti Kan]

Automotive headlight bulbs are designed to operate with the higher
voltage that the alternator generates, so it's a non-issue.  It is
voltage spikes and mechanical shock that would shorten the life
expectancy of the bulb, not the steady-state DC voltage itself,
as long as the voltage is kept within spec.

Thus, there is really no benefit to using a DC-DC convertor and
dropping the voltage to 12V.

Moreover, DC-DC convertors are not 100% efficient, so you'd be taxing
the car's electrical system with an even bigger load than with the
headlights alone.

-Ti
2003 A4 1.8T multitronic
2001 S4 biturbo 6-sp
1984 5000S turbo
1980 4000 2.0 5-sp
--
    ///  Ti Kan                Vorsprung durch Technik
   ///   AMB Laboratories, Sunnyvale, CA. USA
  ///    ti at amb.org
 //////  http://www.amb.org/ti/
///

Todd Young writes:
> We all know that normal voltage to the headlights drops as you turn on
> accessories, thereby reducing the available light output from your
> headlights. Some of us have wired in relays to direct voltage directly
> from the battery to the headlights, thereby shortening the expected life
> of the bulb because it is receiving 13.6 volts rather than 12 volts.
>
> Here's my idea, instead of using relays, why not utilize a DC-DC
> converter circuit with the relays? Input would still be 13.6 volts
> directly from the battery, but with the DC-DC converter, the voltage
> from the battery could be a "range" of voltages, but still have an
> output from the converter set to a steady 12 volts.