Is 18-26 lm/W a good efficacy for a Red LED?

[radmanrugg]

Is 18-26 lm/W a good efficacy for a Red LED?
See http://www.luminus.com/stuff/conten...8f2716e49fa6/pdf/pds_001226_cbt_120_rev02.pdf
Wondering if this would make a good bicycle tail lamp.

My first post so please be kind.
SR

 

[ellerbro]

Not very good efficacy. The Lumileds Luxeon I gets 43 and 53 lumens/watt typical for red and red-orange respectively. Red-orange is still quite red and makes a great rear light. I used two for my rear light and it's plenty bright.

 

[Oznog]

There's a quirky factor that lumens are not a measure of emitted mW energy, but of the human eye response.

1 mW of red @ 630nm actually scores 30% lower lumens than 1mW of red-orange @620nm. So the red actually puts out a bit more light power than the red-orange but it will score fewer visible lumens.

The LEDs you list are in the red-orange range (622nm) and "good" LED tech scores about 50 lm/W there.

Your spec sheet there took the unusual measure of specifying with the Tsink @40C not 25C, and reds lose a lot of output at higher temps. Rebel Red-Orange specified at 25C sink temp and they're down to about 45 lumens/W at the 40C level. Still not enough to make this sound attractive.