On Tue, 01 Nov 2016 09:02:59 -0700, Jeff Liebermann
wrote:

LM-80 = a standard for measuring LED lumen maintenance & depreciation
LM-40 = time for 50% of the lamps in a large group to burn out
L70 = time to degrade to 70% of its original lumens
L80 = time to degrade to 80% of its original lumens
L90 = time to degrade to 90% of its original lumens
Reported TM-21 = predicts lifetime using LM80 + optimistic magic math
Calculated TM-21 = predicts lifetime using LM80 + more optimistic magic math

One more. ARL:
http://www.bulbs.com/learning/arl.aspx
"Average Rated Life (ARL) is how long it takes for half
the light bulbs in a test batch to fail"
I seem to recall others, but I'm too lazy to Google.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558