Bear in mind, Charles, that this paper is talking only about white LEDs, which didn't even exist prior to the mid 1990s, and which have a number of additional failure modes which LEDs without phosphors do not have. On Fri, Jul 4, 2014 at 11:18 PM, Charles Craft wrote: > > http://www.etaplighting.com/uploadedFiles/Downloadable_documentation/docu= mentatie/whitepaper_LED_EN.pdf > > "Early generation and most low power white LEDs typically lose up to 50% = of > their initial lumen output within the first 8,000 - 15,000 hours. Due to > improvements in thermal design and improved materials, high quality power > LEDs nowadays can have average lumen maintenance4 > of 50 - 70% after > 50,000 hours of operation." > > Samsung fridge here and finally got around to hooking up the water line. > Hope they changed the logic on the ice maker since yours came out. > > > > -----Original Message----- > >From: Bob Blick > >Sent: Jul 4, 2014 4:18 PM > >To: piclist@mit.edu > >Subject: [EE] Aging of blue LEDs > > > >My refrigerator has been set to 4F (freezer) and 38F (refrigerator) > >since it was new, about 5 years ago. Last night I changed the > >refrigerator to 40 and immediately noticed that one segment of the > >display was considerably brighter than the others. That segment was one > >that hadn't been lit for 5 years. > > > >Attached is a picture I took. In real life the difference is even more > >striking. > > > >Five years is over 40000 hours, so it's perfectly reasonable that the > >LEDs have aged, but I've had red and green displays running continuously > >longer than that with no degradation. > > > >I've also seen blue and white(phosphor) LEDs age very quickly running at > >200% of their current rating, in just a thousand hours. But the display > >in this refrigerator is probably running within its design spec. > > > >I can't help thinking that blue LEDs age faster than other colors. If > >anyone has real information on this I'd love to hear. > > > >Thanks, Bob > > > >-- > >http://www.fastmail.fm - The professional email service > > > > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .