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Comment by phasetransition | Hacker News Reader

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.

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Since 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?

I 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.

So which led light bulb do you install in your house?

Ikea when the size is available, for reasons I cannot discuss here.

now I'm curious

i'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.

My 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/

It has nothing to do with this. It has to do with details about the OEM for the Ikea product.

Leedarson? (according to http://wastonchen.com/3973.html ) Never heard of them, they make good LEDs?

Leedarson is an OEM for many light bulbs you've seen on shelves in stores.

Do you have preference for a particular line of Ikea bulbs? (Ryet, Ledare, etc)

The higher end line (Ledare?)

Seconded that. I switched to Ikea lamps back in the CFL days and today use their LED bulbs and lamps with no problems at all. Of course they're not manufactured by Ikea, but whichever is the maker it seems a very reliable one.

More 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.

We'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.

I 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?2001IAU...

Is 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.

As 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.

From 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?

Go 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

The 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?

Why 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?

All 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.

blazing is undertaking, the filament is over 2500K

High efficiency is only 50%? Isn't that terrible? Are LEDs really that bad?

Incandescents used to be 5% visible light at best, with 95% of energy turned into non-visible radiation.

I 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.

Or 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.

Partly because they are running tiny cheap power supplies pushed near their limit, and also because many of the actual LEDs they use aren't nearly as efficient as they could be. Also available surface area, in order to fit in most standard bulb locations they need to be small leaving little room for adequately sized heat fins.

yes theres multiple kinds of inefficiencies concerning the external circuitry etc, but there is also the intrinsic inefficiency of current LEDs: some of the high energy photon are downcoverted to a low energy photons by phosphors, so there is non-radiative (heat) generation in the phosphor itself. In theory it is perfectly possible to use "quantum cutting" i.e. 1 photon -> 2 photons instead of 1 photon -> heat + photon. There is quite a lot of research on quantum cutting phosphors, both for LED's and for VUV excitation etc, so these higher efficiencies will probably come, but I don't know how far out in the future. If someone knows of commercially available quantum cutting phosphors (or products using them) I would be very happy to know about them for some physics experiments...

If cost were less of a concern, what engineering changes would you make to the bulb?

#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

There:

  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.

What'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.

There'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)

Second 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.

So, why do LED bulbs seem to last not as long as they should?

I think the parent article provides a reasonably accurate description of why

How do you predict product lifetime?

There 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/1449334...

Thanks. For the lazy... it's explained here:

https://www.eetimes.com/document.asp?doc_id=1280235

For 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-maint...

But, in practice, other components generally fail before the LEDs have a (binary) failure.

Do all types emit RF noise? What to look out for to avoid it?

Any 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.

How much does it cost to make a LED bulb that runs no hotter than 45C at all times?

The 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.

I 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.

Well, thanks for not answering my question in any capacity, I guess...

What do you recommend to buy if I want a ~2700 lumen, high CRI (>90), and non flickering bulbs for home?

I'm not sure for high CRI. See my comments elsewhere about Ikea otherwise.

What do you think of the Phoebus cartel? Is a form of it still continuing nowadays?

Can'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.

What percentage of your sales is in RVs vs homes?

0% We do outdoor lighting for industrial environments

It’s dog hours, right?

What planned obsolescence do you engineer in to your fittings, etc.?

None. 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.

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