Re: LED power efficiency

In <dbe50969-116c-4d51-9278-ff8e7504212c@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
RHRRC wrote:

On 29 Feb, 02:30, m <martin.use...@xxxxxxxxx> wrote in part:

From empirical observation, I find it hard to believe that high-power
LEDs can be 20% efficient.  In other words, 20% of the incoming energy
is converted to light and the rest is heat.  The reality today seems
to be less than 10%.

-Martin

Looking at the 1W Amber Luxeon (LXHL-DL01) using the typical figures
for intensity bin S, color bin 4, volts bin G etc gives an photometric
efficiency of ~12%. Higher intensity and lower voltage bins wiould
increase this figure (albeit this data is with a Tj of 25 degC!).

I would like to know the data (manufacturer etc) of the 30% blue and
21% red devices if at all possible (appreciating this may be
restricted information)

I note that Cree arenow suppling in volume white leds at >110 lumen/
watt reaching 135 lumen/watt
Depending upon how you wish to define the white (I am too lazy/thick
to calculate it for the actual Cree leds spectrum) this would be
250~300lumen/watt for the 'perfect' emitter meaning the Cree devices
are pushing 50% 'efficient'

Datasheets for Lumileds Luxeons state both typical dominant wavelength
and overall luminous efficacy (lumens out per watt in).

The Lumileds AB12 application brief shows a couple curves that indicate
luminous efficacy of the emitted light of their colored LEDs (lumens out
per watt out) as a function of dominant wavelength.

Divide the second by the first to get conversion efficiency. This
appears to support most of their red ones achieving 25% efficiency at 350
mA.
Royal blue Luxeons and some other royal blue LEDs are rated for
radiometric output rather than photometric output, so conversion
efficiency of those can be determined from their datasheets alone.

As for white LEDs - I have one clear determination for one prototype,
331 lumens out per watt out, and I have a feeling that this is a little
higher than usual, due to lowish CCT and its use in a super-efficacious
prototype:

http://ledsmagazine.com/articles/news/3/11/22/1

- Don Klipstein (don@xxxxxxxxx)
.