While the lamps are spec'd for ~14 years of continuous use (at 25C... "yeah, right!"), there's nothing that indicates how the output changes, over time (i.e., use).
The color of the individual emitters shouldn't change -- just their optical power output, right?
Can one assume that equal use will degrade that output equally? I.e., the color produced by *combinations* of emitters won't shift, over time (?)
If it does, is there any practical way to compensate for this (e.g., by tracking the amount of "use" each emitter has seen)? Or, is it too component specific?
Yes, but will that be related to operating current, duration, duration x current, etc. I.e., if you can watch (control) how each is used, can you make reasonable predictions as to what to expect regarding their output (without having to directly *sense* that)?
I did my first retrofit in our laundry/pantry in 2013. I then did all the dual fluorescent 48" fixtures in the kitchen from 2014 - 2019. I made up my own system, using long strips of copper-clad PC board material to mount SMT LEDs and act as the interconnect as well as the heat sink. I made my own constant current supply for the first one, and commercial LED lighting supplies for the others. They are all working quite nicely, and I don't think they have dimmed at all. We use those kitchen lights a LOT, especially in the winter, too.
But you probably are only relying on your day-to-day recollection of their brightness -- do you have a light that you have NEVER/rarely powered to compare against, as a reference?
A neighbor installed some 100W LED fixtures in his front yard. (note that this is roughly comparable to the fixture I cited -- though his are "monochrome") As I've been wanting to replace the 1500W of Halogens that we have in our BACK yard (which see a lot of use and, thus, "operating cost"), I asked him where he'd purchased them, cost, etc. (cheap chinese products from eBay).
As I'd not been able to find a package that I like (no exposed cable to deteriorate from prolonged exposure to heat and UV), I've put off purchasing and installing any. Easier to just pay the electric bill than to spend hours chasing down suitable fixtures!
Last week, I was out, at night, and noticed his lights seemed considerably dimmer. And, I'm 103% sure he doesn't have intensity control on those! :>
So, I asked him about it, the other day. He frowned and nodded that they are, in fact, noticeably dimmer. He said, when he suspected it, he pulled the "spare" (never rely on chinese replacement products to be available "long term") that he had purchased and "plugged it in" (fixture has a long pigtail). Knowing that they've dimmed, he really has little recourse -- buy yet another inexpensive chinese product and hope??
No, I did the first one in early 2013, and did the last one in Dec. 2019, using the same LED part #. If they had seriously dimmed, I would have noticed the difference. I can't really tell any difference between the first and last unit built. Now, because these LED strips are completely exposed above the diffuser, they run pretty cool -- about 45 C at the copper-clad boards. Many packaged lamps have to be seriously sealed because they are not isolated from mains voltage. That causes a huge temperature rise. My retrofits are about 44 inches long by 2" wide, that spreads out the heat.
OK. I'll attribute the neighbor's "problem" to "Made In Chine".
These are 100W units in sealed (waterproof) enclosures. They are intended for outdoor use (see slideshows):
My concern is that if one "element color" sees more use than another -- and, thus has more opportunity to degrade -- that the color(s) formed in concert with other elements will significantly change.
In particular, if mainly showing "green" (and, thus, aging the green emitters) then the light output in contrast with an eventual *red* (signalling an anomaly) could be degraded in such a way that the red and green states are less distinguishable (by an individual with red-green colorblindness).
Repeat for other -- less common -- types of colorblindness.
[If you can't separate indicators so that the position of the indication conveys meaning (regardless of color) -- much like a traffic light -- then you need to rely on other "encodings" to convey the color information.
"Blinking" is a poor way of differentiating state in a color-independent manner so you want to rely on other aspects of the presentation -- imagine if every (US) traffic light was represented by a single indicator that used color and blink rates to convey just those three states (red/yellow/green) instead of standardized "positions"!]
The lattice might degrade a bit with time so the FWHM of the wavelengths output might slowly broaden as well. Not noticeable to the human eye...
The yellow phosphors on the White emitters will be the thing that degrades first. Though some systems now use phosphors for each of RGBW.
Not worth the effort in such lamps since they are generally being used for putting swathes of slowly changing colours onto buildings. And if they were in a theatre they would be on a control console that could if necessary be recalibrated as they faded to correct systematic errors.
I'd expect the blue emitter to be the most fragile but not by much.
In my case, I only use the white emitters for general/supplemental lighting. I *could* use other fixtures for that but it just complicates the control and installation.
Yes. Unfortunately, there are no *other* products that are designed to throw a LOT of "colorable" light (to illuminate large *spaces*)
In a theater, you really want precise control over light color (witness the variety of "gels" that have traditionally been used). In my case, I only want to make sure that the "color choices" (i.e., operating configurations) retain their distinguishability over the life of the lamp. Imagine if your "emergency exit" signs had to be recolored as the RED faded over the years... :>
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