| Electronics > Projects, Designs, and Technical Stuff |
| Rule of thumb in powering LEDs-prioritizing longevity over light output. |
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| cdev:
I want to install some low voltage warm white LED spot lighting for safety and I want it to last a very long time so I don't ever have to repair it. It might be in inaccessible places, etc. Can I just derate it, if so by how much (a rule of thumb) Ive noticed that when I do that they last much longer and dont get dim, but my observation is not based on numbers, just my observation. In contrast it seems that LED light bulbs bought to replace conventional bulbs have a high attrition rate and so I have a bunch of them. I think I may just try to scavenge the remaining LEDs out of some of them to see how that works. I think their short life is probably because they are designed to run kind of hot. The LEDs themselves are probably fine and its the driver circuitry thats failing. Are there any papers that give an overview of the factors impacting LED longevity in a general way? |
| Buriedcode:
I don't have much experience with them but I assumed (perhaps wrongly) that its because often they are for hanging lights - with the (already running hot) driver sitting directly above a hot LED array with little or no ventilation. Both are running at their limits anyway, and their lifetimes are probably given for a more modest temperature range (= lies). Although it'll take a while I would be interested to see a comparison of lifetime for hanging vs "lamp" arrangement. Sorry, its not really what you asked for, I'll just watch the thread :) |
| cdev:
'lamp' for me lasts longer than hanging or sideways. |
| SiliconWizard:
--- Quote from: cdev on October 27, 2018, 08:29:31 pm ---I think their short life is probably because they are designed to run kind of hot. --- End quote --- That's what I have observed as well on a number of LED bulbs. Whether it's intentional, just bad design decisions or mainly cost reduction reasons, I don't know and it doesn't really matter. Most of the home LED bulbs are crap. --- Quote from: cdev on October 27, 2018, 08:29:31 pm ---The LEDs themselves are probably fine and its the driver circuitry thats failing. --- End quote --- Yes, the drivers fail first. They are usually not properly heatsinked and the components are low-quality. The LEDs themselves will end up degrading as well when running too hot. We're just lucky enough that the drivers fail before they end up catching on fire. :palm: ;D |
| texaspyro:
My house has over 300 bulbs (in ceiling mounted cans)... all are now LED. I bought all my LED bulbs from am ebay seller that sold store returns (probably because they did not work with some dimmers). Most are Sylvania (made by Lighting Science Group). When I did the retrofit retail pricing for the LED bulbs would have been over $14,000 dollars. I got the "used" bulbs for less than what I was paying for hot-wire bulbs. Then LSG recalled a lot of their bulbs and they sent me brand new replacements... I'm fixed for life. I have had two LED bulbs fail in the last 5 years (before I was replacing at least one halogen bulb a week... and if the halogen was in the kitchen it usually took out a couple of other bulbs and the dimmer). Both failed bulbs were from the same socket. My LED bulbs are old-school designs with massive aluminum heat sinks (over a pound of aluminum in the PAR38's). Newer LED bulbs are way too aggressively cost reduced. Virtually no effective heat sinking. |
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