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So, engineering lead of a (outdoor) led Luminaire manufacturer here. And our sales director used to work for one of the biggest Asian light bulb OEMs. Happy to
by phasetransition 8y ago
So, engineering lead of a (outdoor) led Luminaire manufacturer here. And our sales director used to work for one of the biggest Asian light bulb OEMs. Happy to answer specific technical questions out there that this article triggered.
- int_19h 8y agoFrom the perspective of efficiency, defined as maximum perceived (by human eye) luminosity per watt used, what's the best color for LED bulbs? Is white as good as it gets, or is there any advantage with pure green LEDs?
- phasetransition 8y agoGo look up scotopic vision, phototopic vision, and metamerism if you want a deeper dive on human vision. Our eyes are most sensitive in the green, but green LEDs are not necessarily the most sensitive
- int_19h 8y agoThe green LEDs are not necessarily the most efficient in terms of amount of light emitted per watt of energy used, if I understand correctly. Hence the question - is the increased sensitivity to green enough to overcome that inefficiency, compared to white?
- arbitrage 8y agoSo, why do LED bulbs seem to last not as long as they should?
- phasetransition 8y agoI think the parent article provides a reasonably accurate description of why
- Pheide1j 8y agoMore of a non-technical question, do you see demand for outdoor lights at the red end of the spectrum? Supposedly that's better for night vision, light pollution and various animals. But everywhere I go I see yellowish sodium vapor lights replaced with white LEDs.
- phasetransition 8y agoWe've certainly been asked about amber LEDs for coastal environment projects, so I think there is some demand. Amber LED performance, on the other hand, is a different story. The lumens out of a legacy high pressure sodium lamp are very high. It is still an engineering challenge to get comparable lumens out of LEDs at price point the market will bear.
- darkmighty 8y agoI think it's a shame sodium vapor lamps are being replaced. Low pressure sodium (LPS) is actually highly efficient, provide a very soothing color for nighttime, and for me most importantly are easily filtered by astronomical observations (their spectrum is nearly a single line). Their size and unwieldiness is justified in utility street lightning setting. http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?2001IAUS..196...81L&defaultprint=YES&filetype=.pdf http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?2001IAU...
- kowdermeister 8y agoHow do you predict product lifetime?
- thomas 8y agoThere are standardized tests for all this stuff, as you might imagine. One in this case would be the LM80 test. Source: https://www.amazon.com/LED-Lighting-Primer-Future/dp/1449334768 https://www.amazon.com/LED-Lighting-Primer-Future/dp/1449334...
- kowdermeister 8y agoThanks. For the lazy... it's explained here: https://www.eetimes.com/document.asp?doc_id=1280235 https://www.eetimes.com/document.asp?doc_id=1280235
- phasetransition 8y agoFor LEDs, LM-80 data is used to extrapolate lifetime data via the TM-21-11 methodology. Its not great, but it is what we have. If you read the standard, it has pretty good summary of the drawbacks of the current approach to lifetime extrapolation: https://www.ies.org/product/projecting-long-term-lumen-maintenance-of-led-light-sources/ https://www.ies.org/product/projecting-long-term-lumen-maint... But, in practice, other components generally fail before the LEDs have a (binary) failure.
- nouveaux 8y agoSo which led light bulb do you install in your house?
- phasetransition 8y agoIkea when the size is available, for reasons I cannot discuss here.
- s9w 8y agonow I'm curious
- cullenking 8y agoi've tried a bunch, and the ikea bulbs do the best in a variety of conditions: - longevity - when used with a dimmer - when a large load is applied to the same circuit Most other bulbs fail one of those, but I haven't had an ikea branded bulb do poor in any condition.
- deleted 8y ago[deleted]
- badgers 8y agoMy guess is that is has to do with IKEA's improving smart home trend [0]. I like the fact that the work with all three major platforms so I don't necessarily have to be all in on one if I decide to switch in a couple of years: "Trådfri [has] compatibility across Apple HomeKit, Alexa, and Google Assistant". [0] - https://www.wired.com/story/ikea-fyrtur-smart-blinds/ https://www.wired.com/story/ikea-fyrtur-smart-blinds/
- phasetransition 8y agoIt has nothing to do with this. It has to do with details about the OEM for the Ikea product.
- sydd 8y ago
- antisthenes 8y agoHow much does it cost to make a LED bulb that runs no hotter than 45C at all times?
- blacksmith_tb 8y agoThe trick is that you have passive cooling (a heatsink) in what could be a completely enclosed space (like a glass shade/globe on a flush-mount fixture). The heatsink can't be too big to occupy a similar volume to a 'normal' A19 bulb, or it won't be able to fit in lots of existing fixtures. I suppose we might see some bulbs try active cooling (with a fan on that heatsink), but people are already very aware of hums and buzzes from their fixtures, so it'd have to a quiet one.
- phasetransition 8y agoI cannot speak knowledgeably to this for A19 type products, but generally there is no need to have such low temperatures to achieve good lifetimes. There may be temperature requirements this low for bulbs mounted in certain locations, but that is not a part of UL 1598 that I have in my brain.
- antisthenes 8y agoWell, thanks for not answering my question in any capacity, I guess...
- pbhjpbhj 8y agoWhat planned obsolescence do you engineer in to your fittings, etc.?
- phasetransition 8y agoNone. Our industrial customers require minimum 5 year warranty at 12hrs on per day, 365 days per year. We work hard to make both the lighting producing and mechanical aspect of the luminaires last.
- rhacker 8y agoWhat percentage of your sales is in RVs vs homes?
- phasetransition 8y ago0% We do outdoor lighting for industrial environments
- chris_va 8y agoIf cost were less of a concern, what engineering changes would you make to the bulb?
- phasetransition 8y ago#1 more die. More die means less current per die, which helps efficacy in a nonlinear way (google "LED droop") #2 better passives. Aluminum polymer caps, for instance #3 lower temps, in however you want to achieve that aim #4 some TVSS element if there wasn't one already
- xxs 8y agoThere: 1) Better cooling: non-tooth paste thermal compound, more space for heatsinks 2) Not overdriven LEDs 3) Introduce DC power lines (within the house/building) - galvanic corrosion still might be an issue 4) In lack of point 3 - more efficient AC -> DC converters, preferably with lower temp threshold, having 150C default for the internal mosfet on 8pin LED driver is really high. 4a) AC-DCs require quality passive components: coil and caps.
- ChristianGeek 8y agoIt’s dog hours, right?
- jandrese 8y agoWhy do so many of the bulbs run hot? Like so hot you can't hold them in your hand if they were on when you unscrewed them. Isn't this a lot of wasted energy?
- phasetransition 8y agoAll bulbs produce heat, both from the LEDs and the electronics. Incandescent bulbs were blazing hot, too, and they radiated IR on top everything else. A high efficiency LED assembly is still producing on the order of 50% light and 50% heat.
- sleavey 8y agoI think they might have began quoting the LED lifetime on boxes, which is still true, but in reality something else in the bulb usually breaks before the LEDs themselves. I guess manufacturers have either taken it upon themselves or have been forced to reduce the quoted lifetime since the famous 100,000 hours marketing.
- jandrese 8y agoOr they quote the lifetime figure for a single LED, but then wire up a dozen or more in series to make the light. Any one of them fails and the whole assembly goes dark.
- lucb1e 8y agoSince the article never answered the question, do you know what happened to the 100k hours LED bulbs? Were the initial estimates just over-optimistic? Was it all marketing hype?
- phasetransition 8y agoI can only guess that the marketing department wanted to put the biggest numbers forward against what was plausible calculations for the early LED lifetimes. I know for a fact that some of the testing houses have done extended on/off cycle testing for some of the big box retailers looking to keep the lamp vendors honest on real lifetime performance of A19 class bulbs. I've been in such a test chamber.
- ceph_ 8y agoWhat's your take on why so many dimmable LED bulbs have flicker/buzz issues? I've tried through 5 different MR type LED bulbs and every one of them had an extreme flickering issue. All of them were labeled as dimmable. I've had better luck with the standard A type bulbs. But only because there were more thorough reviews available.
- phasetransition 8y agoThere's a myriad reasons why flicker and buzz occur, because there are a number of ways to achieve dimming. But all of this comes down to cost. If dimming is important to you, there are a number of architectural grade bulbs that offer deep dimming to 5% or 1%. Personally, for this application, I've had good luck with Cree bulbs of this type at home (on Leviton dimmers). And in the house of worship environment with Cree bulbs on Doug Fleenor dimmers (http://www.dfd.com/dmx8dim.html http://www.dfd.com/dmx8dim.html)
- shadowoflight 8y agoSecond that Doug Fleenor recommendation. They make some fantastic lighting kit. I'd also like to add that looking for lamps with the CEC Title 20 & Title 24 certifications should be helpful in finding bulbs that dim well, as California has much stricter regulations on dimming flicker and buzz than the rest of the country.
- vanderZwan 8y agoIs there a way for me to know whether or not an LED bulb will have a proper driver that does not throw away half the current and produce a "strobe" before I buy it? The flickering (in the presence of moving things) drives me crazy.
- phasetransition 8y agoAs above, look for architectural bulbs that are deep dimming rated (< 10% dimming). They cost more. I personally have had good luck with Cree, but probably the other top shelf vendors have similarly good products.
- Guereric 8y agoWhat do you think of the Phoebus cartel? Is a form of it still continuing nowadays?
- phasetransition 8y agoCan't speak to any of that. The appearance to me as a consumer walking around with an engineering eye, is that the early days of expensive higher end, store exclusive home LED bulbs (e.g. Cree at Home Depot) has given away to an all out price war.
- sydd 8y agoWhat do you recommend to buy if I want a ~2700 lumen, high CRI (>90), and non flickering bulbs for home?
- phasetransition 8y agoI'm not sure for high CRI. See my comments elsewhere about Ikea otherwise.
- fh973 8y agoDo all types emit RF noise? What to look out for to avoid it?
- phasetransition 8y agoAny bulb with switch mode hardware to control the LED drive current will exhibit RF emissions. The cheaper bulb in the original article has linear current control. Inside the ASIC, this could be as simple as a BJT or FET in saturation with a (somewhat) controlled base/gate voltage, maybe with some temperature compensation. The linearly regulated bulb will have less RF emissions, though you could theoretically still have a bit of rf trash from edge effects depending on the rectifier and filter cap. Any bulb that has passed FCC Class B will have an upper bound on conducted and radiated emissions, but you can pass such tests on a wide range of margins, and therefore certification isn't useful to clarify which bulbs have the lowest emissions.
- deleted 8y ago[deleted]