Re: Anyone moved to LED Lighting?

["Josepi" <JRM@xxxxxxxxxxxx>]

I would like to see cites of this. This is quite interesting.
Apparently the Lexus (2008) used LEDs for low beam headlights. Here is an
exepr from a sirte discussing that. The heigh heat put out by LED
inefficiency is a problem.
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Automotive headlamp applications using light-emitting diodes (LEDs) have
been undergoing very active development since 2004.[38][39] The first
series-production LED headlamps were factory-installed on the Lexus LS 600h
/ LS 600h L starting with the 2008 models. Low beam, front position light
and sidemarker functions are performed by LEDs; high beam and turn signal
functions use filament bulbs. The headlamp is supplied by Koito. Full-LED
headlamps supplied by AL-Automotive Lighting were fitted on the 2008 V10
Audi R8 sports car except in North America. The Hella headlamps on the 2009
Cadillac Escalade Platinum became the first U.S. market all-LED headlamps.
Present designs give performance between halogen and HID headlamps,[40] with
system power consumption slightly lower than other headlamps, longer
lifespans and more flexible design possibilities.[41][42] As LED technology
continues to evolve, the performance of LED headlamps is predicted to
improve to approach, meet, and perhaps one day surpass that of HID
headlamps.[43]

The limiting factors with LED headlamps presently include high system
expense, regulatory delays and uncertainty, and logistical issues created by
LED operating characteristics. LEDs are commonly considered to be low-heat
devices due to the public's familiarity with small, low-output LEDs used for
electronic control panels and other applications requiring only modest
amounts of light. However, LEDs actually produce a significant amount of
heat per unit of light output. Rather than being emitted together with the
light as is the case with conventional light sources, an LED's heat is
produced at the rear of the emitters. The cumulative heat of numerous
high-output LEDs operating for prolonged periods poses thermal-management
challenges for plastic headlamp housings. In addition, this heat buildup
materially reduces the light output of the emitters themselves. LEDs are
quite temperature sensitive, with many types producing at 30 °C (86 °F) only
60% of the rated light output they produce at an emitter junction
temperature 16 °C (61 °F). Prolonged operation above the maximum junction
temperature will permanently degrade the LEDs and ultimately shorten the
device's life. The need to keep LED junction temperatures low at high power
levels always requires additional thermal management measures such as
heatsinks and exhaust fans which are typically quite expensive.

Additional facets of the thermal issues with LED headlamps reveal themselves
in cold ambient temperatures. Many types of LEDs produce at ?12 °C (10 °F)
up to 160% of their 16 °C (61 °F) rated output. The temperature-dependency
of LED's light output creates serious challenges for the engineering and
regulation of automotive lighting devices, which are in some cases required
to produce intensities within a range smaller than the variation in LED
output with temperatures normally experienced in automotive service.

Cold weather also brings another thermal-management conundrum: Not only must
heat be removed from the rear of the headlamp so that the housing does not
deform or melt and the emitters' output does not drop excessively, but heat
must in addition be effectively applied to thaw snow and ice from the front
lenses, which are not heated by the comparatively small amount of infared
radiation emitted forward with the light from LEDs.

LEDs are increasingly being adopted for signalling functions such as parking
lamps, brake lamps and turn signals as well as daytime running lamps, as in
those applications they offer significant advantages over filament bulbs
with fewer engineering challenges than headlamps pose.

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"Congoleum Breckenridge" <conbreck@xxxxxxxx> wrote in message
news:4B080FFD.9090000@xxxxxxxxxxx
> I've seen LED back up lights on a couple of newer Luxury cars.
> BTW, The 2009 Cadillac Escalade Platinum has LED headlights.