Re: LED efficiency

In <1182463218.300788.71960@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>, Boxman wrote:

According to a presentation I saw by one LED company, the average
status of high output leds today is for there to be about 45% of the
electrical power in to be converted to optical power, with the
remaining 55% going to heat.

I find that believable for those laboratory prototypes that the high
efficacy claims of half a year to a year or so ago are attributed to.

Come to think of it, the highest overall luminous efficacy I have heard
so far for an LED is 150 lumens/watt, and the second-highest is 138
lumens/watt and that one comes with a mention of conversion efficiency
("wallplug efficiency" often mentioned in the LED industry to mean this)
of 41.7%.

Link to that one: http://ledsmagazine.com/news/3/11/22/1

The most efficacious white LEDs on the market (as of early June 2007
as far as I know) get a lot less than 138 lumens/watt, so I expect them to
be a lot less than 41.7% efficient at converting electrical power to
light, and a lot more than 58.3% efficient at converting electrical power
to heat.

They were speculating that the
theoretical limit was somewhere near 75% of the electrical power in
being converted to optical power. So in your example above, you could
expect to generate about 220 watts of heat with current high power LED
technology devices. I don't know enough about metal halides to know
how that compares.

- Don Klipstein (don@xxxxxxxxx)
.

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