In article ,
John Williamson writes:
Moonraker wrote:
I read recently that LEDs in cars are not as efficient as touted, it
seems they need cooling to work efficiently, so that may apply to the
home as well.

Indeed it does. The lighting industry got a very bad reputation
with the dishonest claims for CFLs, and LEDs started off even worse,
e.g. quoting efficiencies with the LED chip at 25C, which is only
going to apply if you run the thing in your freezer.

The benefits of LEDs on vehicles are the long life and resistance to
vibration.

Also, faster 'ON' time, particularly for brake lights.

However, the lamp cluster needs to have been designed for LEDs.
Retrofitting them into a cluster designed for a filament light
source isn't going to conform to regs.

They also normally fail in a manner that leaves at least some
light being generated by the unit, which is safer than the all or
nothing when a filament lamp fails.

The efficiency savings for mobile use aren't worth bothering about
except for applications like battery powered cycle lights or torches, as
the power used by the lighting on a car is a small percentage of the
total power used to move it. At 30mph on a flat road, the absolute
maximum total lighting load on most cars, including headlamps and
foglamps, is less than 400 watts, as against ten kilowatts or more being
used to overcome rolling and air resistance.

LEDS in fixed installations are noticeably more efficient than filament
bulbs, as they use a switched mode supply, with a total comsumption of
about 10% or 15% that of the filament bulbs for the same light output.

LEDs at that efficiency do exist, but are pricy. Most of the LEDs
you'll see at halfway affordable prices are around the same efficieny
as CFLs, and the cheaper ones are nearer the efficiency of LV halogens.

--
Andrew Gabriel
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