So, what happened to those 100,000 hour residential LED bulbs? Were the initial estimates just over-optimistic? Was it all marketing hype? Or, did we not know enough about LED aging to predict the true useful life of a bulb?
I put these questions to the test. Join me after the break for some background on the light bulb cartel from the days of incandescent bulbs (not a joke, a cartel controlled the life of your bulbs), and for the destruction of some modern LED bulbs to see why the lifetimes are clocking in a lot lower than the original wave of LED replacements.
Any discussion of light bulb lifetime would be incomplete without mention of the Phoebus cartel, an international organization formed in 1924 by the world’s leading light bulb manufacturers to manipulate the bulb market. As discussed by Markus Krajewski in “The Great Lightbulb Conspiracy”, the cartel assigned territories to member companies, limited production, and dictated a shortened 1,000 hour bulb life. Previous bulbs had burned for a much longer 1,500 – 2,500 hours. Purportedly imposed to increase quality, efficiency, and light output, the new 1,000 hour limit also resulted in many more bulb sales. Archived documents show that significant research was expended to devise bulbs that lasted their 1,000 appointed hours and no more. It wasn’t only household lighting that took a hit: flashlight bulbs originally lasting for three sets of batteries were reduced to two, with a proposal to limit their lifetime to a single set. Again, brightness increases were touted as the reason. However, that last step, halving bulb lifetime, would increase brightness only between 11%-16%, while doubling sales. This was about selling more bulbs and making more money.
The cartel enforced production quotas and bulb lifetimes with a system of monetary fines, backed by the power of GE’s patent portfolio. Bulbs from each producer were tested, and penalties imposed for bulbs lasting significantly shorter or longer than 1,000 hours. Phoebus continued to exert influence on the market until World War II ended its reign. The cartel is often cited as one of the first instances of planned obsolescence: designing products with an artificially shortened lifespan. A 2010 documentary, “The Light Bulb Conspiracy,” explores the history of the cartel along with some more recent instances of planned obsolescence. I wonder what the conspirators would have thought of bulbs that supposedly last 100,000 hours? Or even 7,500?
Tucked into a lower shelf in the lighting isle at the hardware store, a few lonely incandescent bulbs waited for some Luddite consumer. Picking up a box, I read the rated lifetime: 1,000 hours.
What exactly does the box mean with this 1,000 hour lifetime? This is the bulb’s Average Rated Life (ARL) — it’s the length of time for 50% of an initial sample of bulbs to fail (abbreviated B50). What “failure” means depends on the type of bulb; we’ll explore this in more depth later on. The definition of B50 reveals a common misinterpretation, namely that a bulb will last for its rated lifetime. In reality, only half of them last that long, although this rating doesn’t tell you anything about the distribution of failures around the median lifetime.
Manufacturers use these ARL values to forecast how many years a bulb will last based on using the bulb a specified number of hours per day (typically 3). LED bulbs suffer less wear-out through power cycling than incandescents, so the conversion is just a division: years of service = ARL/(3*365). For example, half of a set of 100,000-hour bulbs would still be in service after 91 years according to this calculation. But this simple metric doesn’t tell the whole story. LED bulb failure mechanisms are complex and fundamentally different from the well-known incandescents. To understand more, we need to shed some light on the inner workings of a bulb.
There’s more to an LED bulb than just the LEDs. Outlets in our homes are actually fairly dirty sources of AC power. LEDs want clean, constant-current DC sources, so circuits inside the bulbs must rectify and filter the incoming AC, then limit current to the LED packages. To see how this is done, I dissected three different A19 style bulbs: one each from the GE “Basic” and “Classic” lines (7,500 and 15,000 hours), and a Cree model offering a 25,000 hour life.
This GE bulb has a plastic dome covering a circular aluminum PCB which carries eight LED packages and the driver electronics. The driver consists of an MB10F bridge rectifier, an electrolytic capacitor rated for 105 °C, and an SM2082D linear constant-current driver. There are three resistors on the PCB: one bleeds charge from the capacitor when the bulb is off, and two others set the SM2082D current to 54 mA. In fact, the circuit looks like it was taken directly from the SM2082D datasheet.
Seven of the 3.5 x 2.8 mm LED packages show around 18 V of forward drop when driven with 50 mA, indicating that they contain six LED dice in series. One LED on the board shows a drop of 9 V, so it has only three LED chips. All the LEDs, totaling 45 dice, are wired in series to drop approximately 135V.
When they say classic, they mean it. This bulb is in a glass envelope just like incandescents, and like those old bulbs, the glass is easily removed with a ball-peen hammer. In place of the tungsten filament is an aluminum PCB folded into a squat obelisk. Sixteen 3.5 x 2.8 mm LED packages are connected in series on the board, with each one showing a forward voltage of around 9 V at 50 mA. So, this version has 48 LED chips vs 45 for the Basic bulb, except they’re in twice as many packages – this is good for keeping the LEDs cool.
Another difference with this longer-lived bulb is that the driver electronics are not thermally coupled to the LEDs; they are hidden on a separate PCB in the screw base. This keeps the rest of the components from heating with the LEDs. On the driver PCB is a bridge rectifier, an electrolytic capacitor again rated for 105°C, and an SOIC-8 IC. Interestingly, this bulb also contains a metal-oxide varistor for transient suppression. Although I couldn’t determine what the house-marked (“BYSACT”) driver IC was, the lack of any inductive components on the PCB indicates this is another linear supply.
The Cree bulb has a diffused plastic dome like the GE Basic model. Inside, a larger aluminum PCB holds (16) 3.5 x 2.8 mm LED packages. Each LEDs drops around 8.5 V at 50 mA, so they contain 3 chips; like the GE Classic bulb, this one uses 48 total LED dice. The LEDs are wired as eight sections of two paralleled LEDs, so the total drop is around 68 V. The LED PCB is coupled to a thick aluminum heat sink with silicone thermal compound.
As with the GE Classic bulb, the power supply electronics are on a separate PCB, thermally decoupled from the LEDs. The driver IC is an SOT23-5 package inscrutably marked with “SaAOC”, but the presence of a transformer and stout Schottky diode reveals that this is a switch-mode power supply. The filter capacitor on the switcher output is an aluminum electrolytic rated for 130 °C.
It’s not much to go on, but what conclusions can we draw from the design of these three bulbs? It helps to consider how they typically fail, and what factors affect their lifetime.
Since the LED bulbs contain a number of parts, it’s natural to ask which ones might be responsible for failures. The US Department of Energy (DoE)’s solid-state lighting program supports research and development of LED technologies, and their website contains volumes of data on LED lighting systems. Their Lifetime and Reliability Fact Sheet contains data on the failure rate of 5,400 outdoor lamps over 34 million hours of operation. Interestingly, the LEDs themselves account for only 10% of the failures; driver circuitry, on the other hand, was responsible almost 60% of the time. The remainder of failures were due to housing problems, which may not be as applicable for bulbs in indoor use. This data shows that at least for catastrophic failures (where the lamp ceases to emit light), extending lifetime means improving the power supplies.
The lifetime of a bulb (or power supply) can be no longer than the lifetime of any of its components. Among the components found inside the bulbs, two stand out as life-limiters: the semiconductors and the electrolytic capacitors. Both of these components suffer from a failure rate that is a strong function of temperature. The typical model for this effect, based on the Arrhenius equation, predicts a doubling of lifetime for each 10 degree Celsius decrease in temperature, at least over a limited range.
The two longer-lived bulbs use twice as many packages to carry approximately the same number of LED dice as the GE Basic lamp, decreasing thermal resistance to their respective heatsinks, and presumably reducing their temperature. These bulbs also both mount the failure-prone driver electronics on separate PCBs from the LEDs to keep them cool. Finally, the 25,000-hour Cree bulb uses an electrolytic capacitor rated for 130 °C as opposed to the 105 °C caps in the other two. For similar operating temperatures, this could multiply the expected life of the capacitor by a factor of five. Each of these measures probably contributes to delaying catastrophic failure of the bulb, resulting in the longer rated lifetimes.
But when it comes to the LEDs themselves, there is more to lifetime estimates than predicting catastrophic failure.
Like the soldiers in Douglas MacArthur’s famous line, old LEDs don’t die, they just fade away. We all know what an incandescent lamp failure looks like: one second it’s burning bright; the next, it’s not (and every once-in-a-while, you hear a pop followed by a faint jingling as the liberated filament richochets inside the bulb). Power supplies aside, LEDs typically don’t fail with so much fanfare. Instead, they gradually lose brightness as they age. In the lighting industry, this is known as lumen depreciation, and is a separate failure mode from the catastrophic failure we usually think about.
As it turns out, lumen depreciation happens to incandescent bulbs, too. By the end of their 1,000 hour life, the output has typically dropped 10-15%, but nobody ever notices. With LEDs, the effect is much worse, and the output continues to fall as the device ages. At some point, the LED is no longer producing enough light to fulfill its original purpose, even though it hasn’t “burned out.” Research says that most users won’t notice a gradual 30% drop in light levels; accordingly the industry has defined L70, the time at which the output has dropped to 70% of its initial level, as an endpoint for measuring LED bulb lifetime. Based on how it’s estimated, this measure is typically stated as B50-L70, the point at which 50% of an initial sample of bulbs will retain 70% of their rated output.
Something else happens as phosphor-based white LEDs age: they change color. The US DoE’s report on LED Luminaire Reliability: Impact of Color Shift defines four color-shifts (blue, yellow, red, and green) observed in LED lamps, although the yellow shift dominates in high-power white LEDs. This gradual yellowing of the light output results from phosphor cracking, delamination, and thermal effects, since the phosphor temperature can exceed that of the LED junction by 30 C – 50 °C. Modeling and predicting color shift in LEDs is a difficult task, with all of the mechanisms not yet fully understood. As a result, no standards have yet been established for accelerated testing or projection of color stability over time.
Eventually, these effects can be as detrimental to the function of the bulb as catastrophic failure. Given that lumen depreciation and color shift will in time render the LEDs ineffective, it may not make sense for manufacturers to design bulbs with very long electrical lifetimes. It’s possible that the reduced lifetime ratings we see on current bulbs simply reflect better knowledge about actual performance of existing LED technology over time.
I’ve seen lumen depreciation and color shift first-hand. In June of 2010, I replaced twelve 65W incandescent PAR30 floodlight bulbs in our kitchen with LED equivalents. At the same time, I also replaced three lights in another room with identical LED bulbs. These three bulbs see much less use, so in preparation for this article, I took one bulb from each location and put them side-by-side to see if I could tell the difference in output. The recessed light fixtures in both rooms are identical, so I expect that the bulbs are exposed to similar temperatures when on: any difference should only be due to aging effects. The results were shocking. Since these two bulbs were in different rooms, I never saw them side-by-side, so didn’t notice how bad the lumen depreciation and color shift had become. Sure, I knew they were dimmer and yellower than when I installed them, but had no idea it was this bad.
These bulbs were advertised with a 30,000 hour lifetime. I estimate the total use at 15,000-20,000 hours. During the 8 ½ years these were in service, one failed completely. Instead of replacing it with a newer bulb which would not match the color of the older ones (or replacing them all), I left that socket empty.
In the hardware store, I noticed new 9-watt BR30 LED bulbs for $5 each. The PAR30s I purchased in 2010 were $45 and consume 11 watts. A quick calculation says that the old bulbs paid for themselves more than three times over in electricity savings relative to the incandescents they replaced, and put that much less carbon into the atmosphere. They may well continue to burn for another 15,000 hours, but after weighing the degraded output and the cost to replace them with brighter, more efficient versions, I’m headed back to the store.
I’ve taken a look at some of the technical issues in LED lighting. Of course, there is more to LED bulbs than lifetime — color temperature and color rendering index (CRI) should factor into any purchase decision. There are also a number of larger problems involved, including issues of economics and sustainability. Some of these are addressed in J.B. MacKinnon’s 2016 article, The L.E.D. Quandary: Why There’s No Such Thing as “Built to Last”, in The New Yorker.
Certainly moving away from incandescent bulbs to more efficient lighting makes sense, but maybe we never really needed 100,000 hour bulbs in the first place. The lifetime of even 7,500-hour bulbs is long compared to the rapid pace of advance in lighting technology. Does it makes sense to buy expensive long-lived bulbs today, when better, cheaper, more efficient ones may be available in the near future?
The oldest surviving incandescent light, known as the Centennial Bulb (click to see a webcam of the lamp), is a dim carbon-filament bulb that’s been burning nearly continuously since 1901 — over 1 million hours. In its current state, it throws off as much light as a modern 4-watt incandescent. Would it have made sense to pay a premium for such “million hour bulbs” at the turn of the 20th century if we had any inkling of the advances that would come in the next 117 years?
The new $5 BR30 LED bulbs I just installed in the kitchen are amazingly bright and crisp: tests with a lux meter show the illuminance is more than 60% higher. Plus, they’ll more than pay for themselves in electricity savings compared to the old, inefficient LED bulbs they replaced.
I have had very bad experiences with a particular brand of 100W LED bulb (I’ve had about 12 failures in 15 installations, some installations more than once). I’ve given up on 100W LED bulbs, which is too bad because they could save the most money. I may wind up replacing these with more and smaller LED bulbs.
When Home Depot started selling Cree’s, they had a “store return” policy for dead bulbs. The last few times I’ve brought deaders in I’ve been increasingly hassled (although I have receipts, etc).
The 100W led bulbs we got from home depot in general have lasted the good part of a year with fairly heavy use, but the few failures I’ve seen were in a ceiling fan where the bulbs are in sockets with a glass shroud around them (effectively trapping heat around the heatsinks near the end of the bulbs and cooking the electronics). The other bulbs that were in sockets that had more ventilation have unsurprisingly outlived those in the ceiling fan.
Interesting, I’ve been seeing LED bulb failures in one of my ceiling fans and I sort of assumed it was due to vibration. I’d never considered it might be the heat issues from being up in the globes.
Replacing the bath light fixture, I reversed it, (Bulbs facing up) allowing the new LED bulbs to run cooler, and soften the light as it bounced off the ceiling. So far, pleased with the mod.
As someone who works in the lighting industry, the first question I would want to know is if you have a dimming function on any lights in the same room as the fan. If so, someone did not properly run your dimming control wire (more than likely anyhow). It causes interference in a way. The second thing I would do is stop buying Cree and GE… While big names throughout their careers, I find that both companies severely lack in the quality control of LEDs. Try a TCP lamp or a Topaz lamp. You’ll get far better results. Strangely enough, Cree produces they’re own LED diodes, and while they seem to be quality and many manufacturers use them in their fixtures, Cree had seemingly not extended that quality to their heat sink and driver’s.
I’m kind of thinking, buy a higher powered bulb, hack it to produce a lower output which should equal way longer lifespan. It will effectively use bigger heatsinks and heavier components than an equivalent bulb for that light output. Problem solved and all that for the price of one resistor and some glue.
I suspect that replacing industrially soldered surface mount components with some home soldered bits will not actually increase the life of the board in a substantial way. It’s totally possible you could salvage a few more years out of a bulb, but it’s also possible this isn’t really worth it, as the author points out.
That would be doable, except that a lot of them are potted, or have a thick conformal coating, which would be a huge hassle to remove without damaging anything.
At US Lighting Group we have created a bulb (our BH4 in particular), that has a 190,000 hour lifespan. This is not spam, check us out at www .uslightinggroup.com
Ummm…you have LM80 data to support this? I am thinking “No.” That would mean nearly 32,000 hours of testing.
Another potential life shortener in ceiling fans are voltage limiters. They may be gone in the newest models, but I’ve had a number of fans that wouldn’t run CFLs because of them. It’s a box inside the fan that was intended to lower consumption of incandescents. I had to cut a number of them out when working for a university with thousands of students.
Heat is the killer. I was clued into these low powered bulbs on 4chan and have been using them since june 2016, none have blown since. they take about half a minute to brighten after turn on though.
I notice all the bulbs use alumin(i)um “heat sinks”. But what are those heat sinks coupled to? Just thermally connecting the LEDs to aluminum doesn’t solve the heat problem — the aluminum needs to be connected to a radiator or orther room temperature sink. The aluminum PCB does nothing but equalize the temperature between all the LEDs. Unless there’s a place to dump the heat, which lowers the temperature of the PCB, it’s not doing any good.
The little cube of aluminum PCB is cute, but it doesn’t seem to be thermally connected to anything.
But it is. It’s coupling to the air in the bulb, and through the bulb to the outside air. Believe it or not, engineers were involved in the design of these bulbs, and they can calculate (or at least cut-and-try) stuff like this. Also, aluminum PCBs can operate at higher temperatures, which doesn’t do the LEDs any good, but it does affect the whole heat problem. Do you think they’d be using aluminum PCBs if FR4 would do the job?
No need to deal with the store, just call cree. Every single time ive called they just mail me a new one for free.
There seem to be ” infant morality” problems with all electronics. I’ve had many LED bulbs fail in days/weeks where others last years.
That’s known as the Bathtub curve. Stuff is more likely to fail early or late, than in the middle of it’s life.https://en.wikipedia.org/wiki/Bathtub_curve
That’s true of mature products, but the LED ‘bulb replacement’ market isn’t quite there yet. As a relatively new product, responsible companies are still seeing how they can make them efficiently (cheaper!) and still be decent, while competing with ‘overseas’ manufacturers who, in some cases, don’t really care about quality as long as they can finagle shelf space in the stores. Since the cost of processing returns for fails is more than they cost the store to buy in the first place, they don’t stay on the shelves for long. Once the unreliable brands are done being weeded out, the low end of the curve should lift up a bit.
The unreliable brands won’t go away, because they keep switching the brands, relying on the fact that they can sell at least a few batches before they are discovered as bad products.
They persist because people are always willing to try the cheaper options, in case they actually do work. That enables the manufacturers to knowingly push a certain number of bad products on the market.
Meanwhile, I bought a large box of store brand LEDs two years ago and have yet to see a single one of them go out. Maybe the problem is astroturfing for certain brands?
I think that’s highly likely. I also think that you’ve been lucky, if you haven’t had any failures. But it really does seem to be a crapshoot – you DON’T get what you pay for.
Silently screaming. Cursing it’s own brief existence. Yearning for a quick return to the Earth from which all of the components started their journey. One assumes.
It’s been said that the only reason parents survive the toddler years of their offspring is because at that age. the child can’t kill with his/her bare hands and they haven’t yet mastered the art of deadly weapons.
The LED can last that long, but the supporting electronics for dimmable bulbs, and whatever else they need, is the week spot .
Conspiracy theories are a lot more fun than critical thinking. Doubling the life of a lightbulb (by reducing the surface power loading of the filament) results in a 10 % reduction in luminous efficacy. In other words, roughly 10 % more energy is needed over the lifetime of the bulb to get the same amount of light. Over its lifetime, a 66 W 2000 hr lifetime bulb would consume 132 kWh of electricity, for a total cost of 13.7 dollars assuming a 50 cent pricetag on the bulb and ten cents a kilowatt-hour. You would need two 60 W 1000 hour bulbs to match the lifetime and light output, but the total price would now be less at 12.70 dollars. Different bulb and electricity prices would skew the optimal lifetime, but it seems pretty reasonable that the mandated 1000 hr lifetime is a consumer protection regulation rather than an industry conspiracy to rip off consumers.
“Incandescent lamps are manufactured according to British Standard BS 161 (IEC 60064), and the committee responsible for this includes representatives from a wide cross-section of interests such as government departments, professional institutions, organisations representing large users, electrical contractors and the lighting industry. They review all the factors involved such as lamp cost, electricity cost, cost of replacing a lamp, lamp efficiencies at different rated lives etc. and on each occasion they have concluded that the long established life of 1000 hours should remain the standard rating. In fact to minimise customer complaints, the standard filament with a declared life of 1000 hours typically has an average design life of 1200 hours.” http://lamptech.co.uk/Documents/IN%20Life.htm
But in spite of it being slightly cheaper for the customer due to the better efficiency, the bulb manufacturer does sell twice as many lightbulbs.
Either way, whether the original motovation was energy savings or light bulb cartels wanting to sell more bulbs, I’m sure they would be willing to go along with it, seeing as they get to sell more.
Either way, the ultimate cartel called “the government” ended up making the same regulations for the same effect, making the whole question moot.
Those who point at the Phoebus cartel typically do so in some sort of finger-pointing criticism, either against “capitalism” going “see that’s what always happens!”, or to support some other conspiracy theory saying “See, it happens!”.
“Different bulb and electricity prices would skew the optimal lifetime, but it seems pretty reasonable that the mandated 1000 hr lifetime is a consumer protection regulation rather than an industry conspiracy to rip off consumers.”
interesting since the first edition of IEC 60064 was first put into place in 1954, about 20 or so years after the conspiracy claims that the manufacturers got together. I couldnt find the original publish date for the british standard to verify but is it entirely possible that the standard was devised after the fact to justify the corporations conclusions? I mean its not like corporations would never try to convince government officials that what they are doing is good for everyone…. Oh wait…
Never dismiss a conspiracy until you have absolutely all of the facts. It is my personal opinion that the corporations are entirely capable of such a nefarious plot and quite a few corporations have been repeatedly caught in such acts (you know, the rivers on fire kind of thing). If you could prove to me that the standards have been in place since before the conspiracy is claimed then i would be more inclined to believe you but until then…. i will continue to distrust any corporation as historically they have been used to shield individual people making bad decisions for individual profits.
The point isn’t who made the standard, but whether the standard is reasonable and beneficial to the consumers.
The physics of filament bulbs are well known – you can calculate bulb efficiency and cost of electricity for yourself – and tales about everlasting bulbs with great efficiency fall into the same category as the 100 MPG carburetor.
“industry conspiracy to rip off consumers” – Please Explain why Both Asia & Europe’s vehicles achieve MPG #’s that are over Double of the U.S. ? Is it because our dollar is based on Oil ? Why does a 1980 Honda get 50 mpg, but a new Prius hybred only gets 43 mpg. Compare VW.com or Ford.com Vs: VW.uk & Ford.uk ! Why aren’t you & I Allowed to purchase these models (Especially When they’re MADE HERE) ! Greed & Games make me Waste Time stopping for fuel – unnecessarily ! Watch the Film Gas Hole.
Yeah, so about three years ago where I live Home Depot dumped a bunch of inexpensive LED bulbs onto the market (the price per bulb went from $5-$10 down to $1-$3) and they all claimed super high lifetime but many have failed with an interesting mode of failure: they blink annoyingly at rates between 4hz and 30hz. Early in the failure mode they’ll stop blinking and operate normally once they warm up, but eventually the blinking persists longer and longer and becomes unbearable.
So far every time his has happened the LEDs have been OK, as has the capacitor. This smells like an iffy solder joint or something of that nature…
I’ve seen this failure mode in pth and smd discrete leds which flicker as you’ve described due to thermal expansion and contraction of the bond wires attaching the led die leading to an intermittent connection.
I moved into a fairly new home two years ago. The home itself was only 2 years old, so the LED bulbs were less than two years old when they started failing. Blink for a while before finally dying. I took a couple apart. They were Cree brand name and both had failed from poor solder joints holding the LEDs in place.
I’ve seen the same thing happen in a power transistor, caused by the bond wire making intermittent contact and hot/cold oscillation.
I’d suspect that now, but back in olden days (guessing 1980) there was a bad run on one transistor at a US transistor plant (National Semi??) and it was reported in the trade press. The part was typically used in radio output stages (where I encountered one) and it would sound like a power supply cap gone bad. Putt-putt-putt….
This reminds me of the venerable BC148 transistor which due to its unusual construction (google images has photos) could develop cracks and become unreliable although it was a low power device used in no stress conditions.
Funny how my directly heated triodes and rectifiers from the 1920s have filaments that continue to be reliable and light up today. Similar tech but different ‘needs’.
Filaments last almost forever when they run red-hot, like in vacuum tubes. It’s when you run them white-hot that you get significant evaporation of the tungsten, resulting in failure within a year.
When we built our house five years ago, I put LEDs in every socket. The first half dozen times a bulb burned out I took apart the bulb and every time it was the power supply that failed, not the LEDs.
As a result, it is now my policy to never use dimmable bulbs unless that socket is on a dimmer. The extra complexity of the circuitry only means more opportunity for failure. Is it true? I don’t know, but it seems logical.
On the contrary. The dimmable bulbs are made to deal with large voltage variations, because most dimmers work by cutting the AC waveform which causes a huge voltage ripple that kills the non-dimmable bulbs’ input capacitors. The non-dimmable bulbs are less resilient against power quality issues.
All else being equal, more non-redundant parts in the critical failure path always results in lower reliability. If you want better reliability use better parts and/or add redundancy.
Though if the MTBF of those parts count in the millions of hours (such as a simple filter coil), then the question of reduced reliability through part count is really only nitpicking, considering that the extra parts make the other parts last longer.
I’m doing a house remodel now, and my lighting will be all LED strips with separate 12VDC power supplies. Aside from any improvement in lighting characteristics (like, having the light more evenly distributed), it means that I can easily replace each component as it degrades, fails, or is improved upon. It also future-proofs the installation for control options. And, low-voltage lighting isn’t subject to the same code constraints as 120/220V wiring.
I have a 12V power supply in the cellar and fed a strip of LEDs under the kitchen cabinets (with a PWM dimmer). I also have some motion detectors and night lights in dark stairways. If you have a low voltage distribution, you can power all kinds of stuff, like routers and modems, that take 12V. Gets rid of a whole bunch of wall warts.
It seems silly to have 3 wire 120VAC run over #12 Romex* wire to run an LED. *Made once upon a time right here in Rome, New York.
Distribution losses at 12V are pretty awful, though, and modern wall warts are pretty efficient. It could mean less clutter, but only for low power devices.
There are 24 and even 48V LED strips. For “serious” lighting jobs I use at least 24V ones. The 12V ones can be pretty awful because of the voltage drop in the strip itself. Sometime after a few meters of strip you have just 8 to 9 V left.
I think you are on the right track. The age of A19 and similar bulb sockets will have to end in order to realize the full potential of LED lighting. Cramming the power supply, with it’s heat-sensitive components, into a small form factor bulb along with the emitters is a recipe for short lifetime.
The best LEDs now have a power efficiency in excess of 50%. As technology improves efficiency even further, heat generation in the lamp will become less of an issue.
FWIW, get high-CRI LED strips. I bought a reel of the ones that ‘DIY Perks’ (search for it here) used for his photo/video lighting, and a 2m strip (on a PWM dimmer) lights up a 4m x 8m room with light of *excellent* brightness and quality.
Why don’t you just use POE lighting. Need a POE network switch and standard Ethernet cable. Ubiquity has some panels and I know Williams Lighting has a few different Luminaires. Circuits are generally limited to under 100 watts, that’s more due to the limitations on data cable.
Because I’m allowing for high-power configurations—these are the main room lights. Also, my setup allows for 120VAC power (at up to a couple of amps per circuit) to be mixed with the 12VDC wiring, in case I find I need it for something in a particular room. It’s a lot more flexible than I went into in my rather brief description.
a. Lower wattage LED Lights last the longest… no surprise here, as low Watts = less heat which tend to affect lifetimes. However lights purchased from 5 years ago certainly lasted longer than one’s purchased in the last 2 years. Hmmm… designed obsolescence perhaps? In almost all cases the failures were the drivers and not the LED themselves.
b. High Output LED’s have the largest failure rate. This makes sense because of the heat issues from the high wattage/brightness. However, 90% of the failures were the drivers…About 10% were LED failures which then knackered the drivers.
As for “warranties”… hogwash I say. As an example Meanwell markets their drivers from 5-7 years and yet I have sites where their drivers start to fail at about 3 years (about 40% failed at this time frame)…. which is well within their warranty time period. However, to claim the warranty one must send the driver back to a depot in the US + pay for return and reimportation of the replacement driver. Outside of the time/effort to document and package the returning driver, the shipping costs (return + replacement) is about the same as the cost of a new driver… So the warranty is pretty much useless. In fact it seems that the last person to touch the light is the one that has to honor the warranty claim. Around here, most electricians refuse to supply LED fixtures and will simply install whatever fixture that someone else provides (customer, general contractor, etc) so that they are off the hook for warranty issues (replacement + time/effort to remove and replace the fixture and driver).
Interestingly. all of the LED fixtures we have designed and manufactured ourselves (low and high output … 20000 lumen) have had an extremely low failure rates (about 1 in 10000… a cap crapped out) over the past 5 years and so it would appear that it is possible to have high reliability LED fixtures
Good news.. I just installed a ceiling light with color temp adjustment. I replaced the standard 48″ tubes with the LED hoping for a longer life. Don’t start on the CFLs Those bastards.. I suspect it’s cheaper to print the 100,000 hour numbers on the package, than actually spend time testing.
If you want efficiency, you’d rather replace the standard 48″ tubes with standard 48″ tubes with an electronic ballast. They beat most LED products on the market on luminous efficacy (lm/W), except colored LEDs and some poor quality white LEDs that are actually light blue.
The question then becomes, do you want to save money or a negligible amount of time changing a tube a year sooner.
Your argument may be valid in terms of lm/W in favor for Fluorescent… but with Fluorescent tubes have a higher fixture cavity loss and so more lumens are needed to light an area than LED (e.g. the tube emits light in all directions where LEDs are much more directional… and so more lumens where you need it). So… comparing lumens where you need it, you will find that LED are way more efficient. As an example… our Fluorescent LED replacement product consumes 14.7W total (LEDs and the driver) produces slightly more light than a 32W T-8 (assuming a ballast factor of 1 and so the consumption is over 32W).
@Ostracus Even with the reflector, the fixture cavity loss is high, as not all of the lumens generated by the Fluorescent tube goes downward… where you mostly need them. Also, our 14.7W LED (retrofit) VS 32W T8 comparison was based upon the exact same fixture in order to have an apples to apples comparison.
That’s rather difficult without a real integrating sphere, because the individual LEDs cast their light in a narrower angle, and their combined beam pattern isn’t uniform. In other words, if you put a lux meter underneath the light, you can find spots where it’s brighter or dimmer – and that’s still missing the point because the fluorescent tube lights up a lot more than just the floor directly underneath the fixture. Depending on the reflector, the light can be going more than 180 degrees around.
Point being that in order to light up a _room_ you want the light onto the walls and ceiling as well to create diffuse light that doesn’t cast shadows. Ambient light makes the room bright. Pointing most of the light directly down to appease a luxmeter is cheating.
@Luke You are quite correct about a true comparison using an integrating sphere and only taking a single measurement from just below the light. However, you are assuming that our comparison was solely based a light meter under the light… which is not true. In most applications where our lights are used (offices, warehouses, etc) overly lighting the ceiling and walls is not needed. The goal is to improve lighting and energy efficiency on the actual work areas which tend to be downward from the fixture and not the walls or the ceiling. Taking all this into account the result has been a substantial reduction in energy use (min 70% without additional controls), more light where the room occupants need it, and nothing my kudos from the room occupants.
>”overly lighting the ceiling and walls is not needed. The goal is to improve lighting and energy efficiency on the actual work areas”
That is a special case where you would save even more by placing spotlights on the work stations instead of overhead tubes – but that would probably create annoying contrasts.
If you take the case in general, take the average room. Or let’s just take my room for an example. I have various lamps around the room that collectively equal about 200 Watts worth of standard bulbs – but they’re all spot lights that illuminate a desk or an area of the floor. Then there’s one 73 Watt halogen bulb hanging off the ceiling. Turn all the spotlights on, and the room still looks like it’s dimmed down. Turn the spotlights off and the ceiling light on – the room looks bright. For general lighting, directional lights aren’t more efficient because you actually don’t want to throw the light at the floor – you want to throw it everywhere around in order to provide diffuse ambient light that lights up the whole space.
My motivation would be to save the flicker of the starting tube and the warm up time in a cold basement room.
Contemporary house wiring (no to mention most installed dimmer switches) are laughably unsuitable for the widespread usage of LED lighting they see nowadays. I often get asked “what dimmer switch do I need to buy if I want to dim my new LED bulbs”, a question I can not answer because “compatibility” between the two is but a game of chance. All the while, in principle dimming an LED would be such an easy thing to do. But not when you have to do it by somehow manipulate the incoming mains supply into “tricking” the bulb circuitry so that it may pass less current through the dice in the end… what a mess :-D
I’ve not seen a good dimmer – LED bulb combination that worked well. Spiky TRIAC hacked AC must not be easily translated into adjustable constant current drive. Usually the LED flickers and only dims down to 80% of full brightness — unacceptable for this dimmer freak. In the few places in my house where I want dimming control I still go with halogen bulbs.
A lot of dimmers designed to use with LED bulbs have an offset adjustment screw, which you can use to align the bottom of the knob to just barely on. I’ve never had a problem with it, running Cree, Philips, or Ikea bulbs.
What I will say, though, is that you may need to stick to the same model of bulb if you want consistent dimming. Often if you switch to a different brand or model, you’ll either have a minimum that’s quite bright, or not have any light until the knob is at 50%
Dimmers are the reason I haven’t replaced most of my incandescent bulbs. I have room-fulls of 100w BR40s (18 in the dining room and family room) that can go from a soft night-light glow to pleasant, room-filling brightness. I have tried all of brands out there – they either don’t dim low enough or don’t get bright enough (or both). The sunset effect bulbs come close, but even with compatible dimmers, they fail at both ends of the range. The only option I see is to replace the fixtures, wiring and dimmers with a commercial system, which would be price prohibited. And BTW, as far as bulb life, I have a half dozen BR40 100w 130V Sylvania bulbs, on old-school Lutron Skylark dimmers, that are used for hours, multiple times each day, that the bulbs have not been replaced since we moved in the house… 25 years ago! ???? The only really dimmable bulbs I have found, just recently, are some vintage/edison style GE bulbs 60w equivalent (560lumen) that actually work well with my non-compatible Lutron dual dimmer. They dim down to a glow and up to full brightness. Now if the only made a 100w BR40 version… ????
Make your own LED bulbs, buy the emitters from component supply sites, get name brand supplies (avoid the thrift Chinese/auction sites, fakes, etc). Run the emitters at 1/3rd the current that the bulb makers do. Build a decent buck/boost driver for them. Use a good heat sink. As an extra bonus, they will be twice as power efficient as the premade ones (check the spec sheets, they may list lumens/watt at low current). Enjoy your efficient long lasting light for the rest of your life, or until it is zapped by a thunderstorm, dropped, or something better comes along.
I’ve also noticed that along with 100,000 hour claimed lifetimes disappearing, so have the massive cast-aluminum heat sinks earlier LED bulbs used. These probably drove up the cost considerably.
I recently did a lighting changeover in an apartment building, from CFL to LED. Current draw went from 300-350ma to 125ma per bulb. We found that by upgrading from 3000k to a 4000k brightness bulb had a slightly higher cost, we could lower that current draw down to 75ma. Spread over 250 bulbs in the building we calculated our power bill will drop by 2/3rds. The 30,000 hour bulbs are guaranteed for minimum of 3 years.
3000k and 4000k don’t describe “brightness”, they tell you the colour temperature. Counter-intuitively lower numbers are “warmer”, with the bottom of what’s typically available in the 2700k range being very much like the colour of a low wattage incandescent, and 5000k being more of a daylight colour. 4000k is a good compromise of the two. That said, unlike with incandescents, you can get high lumen 2700k, or dim 5000k bulbs. What you want to look for to show brightness is the “lumens”, which are actually the amount of light you see.
In general, you would choose based on where they’re being used. Personally, I would only use a “daylight” white bulb in a work area, and a nice low colour temp where you would want to relax.
There is usually a slight efficiency bonus on higher colour temp (more daylight/bluish) LEDs, but filling your house with 4000-5000k bulbs based on efficiency alone makes it feel like you’re at the supermarket, not at home.
The color temperature does not directly tell you how the light will appear. That depends on the overall brightness of the light.
At lower lighting levels, redder lights should be used to preserve correct color perception. Otherwise your light will seem too harsh, and you actually see worse despite the apparent brightness. 5000 K bulbs are rarely suitable as general room lighting – they’re more of an office/workshop lighting, while living areas work best with 2800 – 3000 K and outdoor lighting even lower color temperatures because the overall intensity is often much less.
Don’t forget CRI, Color Rendering Index. It’s a comparison between an artificial light emitter, which spike at certain wavelenth and varies by lamp, and daylight, which has a nice curve. Even lights that have that not the same temperature can appear different depending on where the spikes are.
I just dissected a LED bulb that failed, and found that the first LED in the string on the lighting board had failed, with an obvious black spot under the yellow dot. Before it failed completely, it had been doing the on-off flicker every few seconds.
A place I used to work had 400 volt AC fluorescent fixtures. When I bulb failed, I would call Facilities and say that a bulb went “Disco” and gave the location. They knew what I meant…
So, because of the constant current driver that the LED bulbs seem to have, you could probably just bridge the failing LED and have a working light again. Would be better if these LEDs had this mode of failing designed in, like some of the old Christmas tree lights where al the incandescent bulbs where connected serially.
It gets complicated. I bought a fixture from Lowes which had a CC driver, but the LEDs were wired in series-parallel. That is, 3 in parallel, with 4 strings in series. So if one LED opens up, the other 2 bear the current, which hastens their demise. If one shorts, no problem, the light is just reduced. But I haven’t seen any that short out unless they were overvolted, highly unlikely in a CC fed string.
So far, they’ve run a couple years no problem. Some reviews said “they all burned out quick”. Maybe they overheated, I dunno.
>” Again, brightness increases were touted as the reason. However, that last step, halving bulb lifetime, would increase brightness only between 11%-16%, while doubling sales. This was about selling more bulbs and making more money.”
“Only”? The bulbs cost cents, while the energy used to light them cost dollars, so the savings to the consumer were still greater than the money they lost by having to replace bulbs twice as often. Win win.
The real point of the “cartel” was, that the industry was going down the drain because it was a race to the bottom. The sellers were competing who had the -longest- lasting bulb, which became the de-facto metric of quality and the resulting bulbs were dim and wasteful, and highly variable in quality to the point that they were barely any better than gas lighting. That 11% more brightness also meant the color temperature went up, and controlling for the lifespan (filament temperature) means the color of the light, efficiency, and power rating became consistent between bulbs.
Ironically, today, with standardized CRI, color temperature, and power ratings, the effect is the same: incandecent lightbulb lifespan is the same between all manufacturers without a cartel being in place. The government eventually did the same job because it made sense to compromise on the lifespan of the bulb to achieve these other good qualities.
How about the longevity of fixtures designed specifically for LEDs? Recently I bought a cheap LED shop light which had string of LEDs as well as the driver electronics were mounted directly on the long metal frame — the entire fixture was the heat sink and I don’t think anything got much above 40C.
Sounds more like the fluorescent fixture form factor with the hard part in the ballast,and the bulb having a lot of surface area.
From what I know heat is the killer of LED (electronics), and part of that is using LED lamps in armatures designed for incandesent lights. For most of my lights I find it sort of fun to buy cheap loose LED’s and COB panels from Ali and design my own armatures around them, and use separate power supplies.
>”Were the initial estimates just over-optimistic? Was it all marketing hype? Or, did we not know enough about LED aging to predict the true useful life of a bulb?”
Yes, yes, yes – and the fourth point is that manufacturers used fudged up numbers to fake lifespan, because there wasn’t always a standard on how to measure it, or adhering to the standard wasn’t necessary to sell them. Different incomparable metrics were used between LED bulbs. Some measured light output drop to 70%, some to 50% and some to total failure. Color temperatures could shift around as well.
The fifth point is that the earlier LEDs were a lot dimmer – the manufacturers made wild claims about what power of a LED was equivalent to what incandescent bulb, so they sold people 3-4 Watt lights claiming them equal to 60 Watt lights, again, due to a lack of common standards on how to measure it. A common trick was to claim equivalence by luminance (bright light over a narrow angle, won’t light up the entire room). These less powerful lights wouldn’t heat up so much, so they’d last longer.
>”The new $5 BR30 LED bulbs I just installed in the kitchen are amazingly bright and crisp: tests with a lux meter show the illuminance is more than 60% higher.”
You don’t know if they actually put out more light or less, because the light is directional. If you replace an omnidirectional bulb with a directional bulb, you’re likely to dim your room despite measuring higher luminance directly under the light, because the indirect light through the ceiling and walls is less. The room is dimmer, except directly underneath the bulb.
Yes it is, which might explain why the kitchen lights use a lot of them mounted to a metal plate which doubles as a reflector as well as heat-sink.
Even with recessed/directional bulbs, a common trick is to narrow the beam further by 5 degrees to maintain luminance directly under the lamp, reducing it at the edges. Lux-meter shows higher brightness for same wattage – consumer is happy and thinks they got more for the money.
Regarding planned obsolescence of incandescents: When I was a lad (US, 1950s) you could buy one set of bulbs for your house and never buy a replacement. The energy utility had a bulb-swap program, where you took your duds to a convenient location (like a drug store) and they’d give you the equivalent new bulb in exchange. This lasted at least a dozen years until someone, probably the bulb makers, sued the utility. I never understood how this swapping made any economic sense, but it was good for us, so…
Of course they gave you long lasting – inefficient :-( – bulbs. They liked it when you wasted electricity and bought more of it. With the swap program they could ensure that you never “accidentally” used more efficient bulbs.
Great article. I’d love to see one about dimming circuits next, especially if you’d be so kind as to explain why the minimum brightness of LED bulbs is so much brighter than a dimmed incandescent.
I’ve given up searching for LEDs that can provide a minimal glow at night, after several disappointing purchases.
It’s because the incandescent bulb is a diffuse light source (especially with frosted bulbs) while LEDs are point sources so even a tiny bit of light puts a hole in your retina when you look at it at night.
For minimal light output, get one of those LED decoration light strings that are meant to go inside a bottle or a vase, with a single AA battery driving it. Replace battery with a wall-wart and you got yourself a night light:
If you to use a quality dimmable LED bulb, they will normally recommend a handful of compatible dimmers. I have two Philips flood lamps in my hallway with a dimmer specified on the box and I have full dimming capability down to a barely visible glow to full brightness. Most lower cost dimmers are not truly compatible with LED bulbs. Get yourself a recommended dimmer for an LED bulb that actually lists compatible dimmers on the box and you will notice a big difference. Yes, it will cost you more, but well worth it.
Get a dimmer meant for LEDs, and read the manual. There’s usually an adjustment screw on them somewhere that sets the minimum chop voltage on the triacs. The minimum brightness of a dimmable led is usually very dim on decent quality ones (though it won’t get as orange/red as a filament so it will look different), but an incandescent will need significantly more voltage before it does anything, so a dimmer meant for incandescent, or an unadjusted LED dimmer will have the zero point set much too high. One disadvantage is that different bulbs will dim differently, so if you have different bulbs on the same dimmer they may power up at significantly different settings. Likewise, if you set the dimmer for one bulb, and then switch to a different model or brand, it may be quite different.
We’re able to see spectacularly low light levels. I work in a group that designs LED drivers. We quote being able to dim 50,000:1 on some of our drivers, and you can still see the LED glowing at 1/50,000 of its full rated value. Incandescents emit light differently, as a function of temperature, and at some minimum temperature they’re emitting a pile of infrared but no visible light. All of an LED’s output is visible (or UV) so if it’s rated to, say, an amp, it’ll visibly glow at a hundred microamps. Switching regulators dim through reducing the duty cycle, and it’s very difficult to reduce the duty cycle to 0.01% because of jitter in the pulse length of the positive part of the duty cycle.
Purkinje’s effect means we get less sensitive to the light as you turn the dimmer down, because color vision starts to dissapear at lower lighting levels. Red colors vanish first.
The LED keeps emitting blue and green even when dimmed, which makes it stick out in the darkness. People also perceive stroboscopic light down to 1/2000th of a second due to the persistence of vision effect, so the PWM method of dimming doesn’t work at all. In fact it is used in many flashlights to increase battery lifespan because you have to drop the duty cycle a lot before the apparent brightness starts to go down.
The incandescent filament has a highly nonlinear response curve. At half power it is a dim red glow. The LED has a highly linear response between current or power to light output. The relationship between voltage or PWM ratio to power is varying greatly depending on PSU technology and structure.
It’s not rocket science; it’s simply that you get what you pay for. Consumers want cheap LED bulbs, so manufacturer’s skimp on the power supply circuitry. (it’s been that way from day one actually). I have never seen an LED bulb fail for LEDs. They have always been power supply failures and when opened, you can almost always see long term thermal damage to the parts or PCB. Have you ever felt the base of an LED bulb? Crazy hot. The LED can handle that as long as the heat is flowing away from the element, but typical power supply components are not fans of that much heat over long periods of time.
Funny thing is that I have some of those “$2 Home Depot with SMUD discount LED Bulbs” from years ago and never had any issues with them. (SMUD is my local electric company) They are only 40W equivalents, but have outlasted a handful of 60 and 75 watt equivalent LED bulbs. My real test is the 100W Philips LED Bulb that I have for my porch light. You can feel the heat from it’s base nearly like an incandescent. Lasted nearly a year so far with being on all night, every night. We’ll see.
The cheapest LEDs don’t have a power supply driver – no electrolytic capacitors – they have two LED strings in opposite directions with a constant current limiter.
They are stroboscopes, but they’re cheap and they last. The moment you add a capacitor to smooth out the ripple, the lifespan drops to the failure rate of the capacitor which is sensitive to line power quality and ripple current (dimmers).
The more expensive lights then add transient voltage suppressors and power factor correction circuits to play nice with -other- equipment, but then you’re talking about $20 per bulb, and at that price you expect something better than low CRI, narrow angle, uneven light distribution, low wattage lights.
Not the cheapest kind. That’s because they can take the nominal power of the LED dies and print that on the box as the power rating of the bulb, even though each LED only runs half the time.
I have one LED light that says 4 Watt on it. Actual power draw measures at 1 W. They put a 4 Watt LED in it though.
I honestly can’t stand LED lighting of any kind, the color spectrums are nearly identical to fluorescent lighting. The strobascopic flicker makes me dizzy and nauseous. I have a 30 plus year supply of incandescent bulbs and halogen reflectors, most are on dimmers , so that helps with power consumption and they seem to last several years when used with a dimmer switch.
I’m sorry, but this is almost completely incorrect and suggests that you’ve either never seen a proper LED bulb in your life, or just don’t realize that you have. I had a similar argument with an uncle of mine once – he “hates those new LED bulbs” but we were having this conversation in my LED-lit living room and he was very surprised when I pointed that out to him.
First, the color spectrum is completely different. Fluorescent lights typically use three-color narrow-band phosphors, red, green, and blue, with very obvious spikes in the emission spectra at each. LEDs use a wide-spectrum phosphor blend with only one strong peak in the blue, where the die itself emits. There’s an interesting article here with measurements: https://www.popularmechanics.com/technology/gadgets/reviews/g164/incandescent-vs-compact-fluorescent-vs-led-ultimate-light-bulb-test/ The article is old enough that their conclusions about brightness and cost-effectiveness are outdated, but the color measurements summarized on the first page are still valid. You can even find those same charts repeated in every LED datasheet. There was one horribly-colored LED bulb in that test, but I haven’t seen anything like that elsewhere or recently.
Second, the only LED lights I’ve seen in the last decade with stroboscopic flicker are cheap Christmas lights (unless you’re running an LED bulb on an unsuitable dimmer). I’m extremely sensitive to LED flicker – I can see it in some car taillights, LED Christmas lights, cheap flashlights, and in magnetic-ballasted fluorescents. I cannot see flicker in modern LED bulbs.
There are a huge variety of different LEDs on the market, and many of them are far worse in terms of flicker and color specrum than even the cheapest fluorescent tubes.
You only have to look at the CRI rating on the box. Most fluorescent tubes are at least 87, while many LED products come in at 72 – 75. Some “white” LED lamps have a CRI/Ra rating of 52 which is the case when you have a blue LED with one of those “broadband” phosphors that mostly emit in yellow.
That can be quite variable. Some poor quality LED bulbs will have a ton of ripple, or even be unregulated with nothing but a current limiter. Most decent quality bulbs have very little flicker. Likewise, with the spectrum, they can vary a lot. Good quality LEDs will have a fairly wideband phosphor, and can have CRIs well over 90. Cheap ones often do have poor quality phosphors with lots of peaks and voids. The worst are often ones built from leds that are intended for indication, as opposed to illumination. They’ll often have a phosphor which is mostly emitting yellow. If you look at the led, it looks white, but they will light a room very poorly, strongly emphasizing blue and yellow, with very weak reds and greens. Fortunately, these are mostly limited to the very cheapest designs assembled from dirt cheap through-hole leds, etc.
CRI can be a good indication, though it doesn’t tell the whole story, since it’s a one dimensional score that can be lowered by different effects.
In general a high CRI (>90) is going to be almost indistinguishable from an incandescent. One in the 80s will generally look fine and probably won’t be noticeable, but may occasionally emphasize or de-emphasize certain colours. Below that is where the badness of the light starts to become obvious.
Another thing to keep in mind, is that LEDs come in different colour temperatures. Many people who don’t know any better will buy the bulb that’s brightest and most efficient (Biggest numbers on the box). Unfortunately, the brightest and most efficient are usually 5000k daylight bulbs that look very stark, and out of place in many situations. A 2700-3000k will often be around 20% less lumens at the same “equivalent wattage”, but will be a lot more incandescent like in appearance, and will often have a better CRI as well. 4000k is good in a workshop type situation where a “whiter” light is appreciated, but without going all the way to “daylight” which seems way too bluish in most situations.
Don’t forget that there’s a tradeoff between luminous efficacy and CRI. The worse the color, the more lumens they can push out by tweaking the spectrum, because lumens are a subjective measure of brightness, not absolute emission power.
Ironically, the most efficient and best CRI LEDs are hybrid designs with external phosphors, making them work like fluorescent tubes. They shine a near-UV light at a plastic diffuser that is filled with the same phosphors you might find in a CFL tube, which then produces the actual light. The best ones also add red diodes to patch the bottom end of the spectrum, so the actual bulb makes pink light and the phosphors fill in the gap between.
Great article. My first LED bulb failed a few weeks ago, after just one year of operation, being lit less than 3hr/day. Disassembled it, the LEDs work fine, but the constant current chip is dead.
I regularly “steal” LED-Bulbs out of the recycling-bin at my local home depot to harvest LED-chips and other components and I see all kinds of failures when I disassemble them. In my experience the most common failure is in the bond wires. I think 4 out of 5 have a black spot in the COB, a filament array or a LED-chip.
It may be worth noting that commercial LED fixtures have moved almost entirely to having separate constant current drivers and LEDs. Sometimes the COBs themselves are replaceable, and other times you have to replace the whole ‘light’ portion, depending on the quality. When dimming is done the driver gets constant power (with perhaps a relay for ‘all off’). The level is set either with an ‘analog’ 10V system (sink or source), 110V phase-cut dimming just for control, some standard electronic bus like DALI or DMX, a proprietary system like Lutron, or, proprietary wireless systems. The lowest dimming level tends to depend on the quality of the driver, ranting from just 1/10th power to full, smooth dimming to black. Of course, the drivers may end up needing to be replaced if the voltage and current of the replacement LEDs have different requirements, but even then the higher-end drivers have some mechanism for setting the new current required.
It should be noted the nice thing about the “1-10V” sink analog systems is that you can dim them with a simple potentiometer. Though you may still have to have an ‘off’ switch if the driver won’t dim all the way down to zero, but you can buy standard decora mount ‘dimmers’ with that both built in.
I opened one LED bulb that started flickering and then died. From what I could see, problem was in the fact that wires from LED driver board were not soldered to the bulb base, but were just touching (!). No soldering, no nothing, just the wire tension held the contact. Outrageous. How can such a thing pass any inspection is beyond me.
They have inspection on a Chinese assembly line? I think they just put 120 volts on it, and if it lights it ships.
Problem being, they didn’t test if the charger still works after being abused. This was used as an example case of QA failures.
I seen it happen with “quality ones” as well. I think brands like Phi1l1ps have at least a little bit of quality control. The wire which connects to the “screw part” of the edison-based bulbs is, at least in the bulbs which I taken apart by now, almost never soldered.
They’re either welded or compression/spring loaded because in a failure the solder would melt away either way.
I bought a Tektronix 475 oscilloscope in 1975, and the input amplifier board for one channel had never been soldered. It worked for a while…. Even the most highly respected manufacturers screw up occasionally.
I think, that’s a typical case of “you get what you pay for”. I have 20 or so 6W-Spots from a German manufacturer in my Workshop which sport “made in EU” on their casing. I bought them six or seven years ago and they have at least 20,000 hrs on them. No failure yet.
I was skeptical, but bought a couple because they were cheap. They’re only a few months old, but haven’t failed yet and are reasonably dimmable.
What sort of compromises are happening inside of these types, with no filtering? Will the LED elements themselves deteriorate faster?
They actually have the electronics in the base, it’s just very compact and potted. Helps with using the screw socket as heatsink for the electronics.
Mine (ebay) did not last long. I left them on continuously in a fixture in a stairwell. The brightness decreased dramatically near end of life. (I didn’t take notes, but it seems like it was less than a year.)
LEDs run on current and only conduct when above their threshold voltage. So you have all the current being drawn near the peak of the voltage waveform. If they don’t have a current limiting circuit then they’re being overdriven to get enough light out of them. Many LEDs have a constant current power supply which eliminates the problem; many do not because they are expensive, big, and heavy. If you leave LEDs on continuously, get some with constant current drivers. And keep them cool, not enclosed.
I have found the sweet spot for LED bulbs is the 60watt equivalent. Not too much heat in that socket end, the best price point. I want our purchaser to get those multiple socket-sockets that have 4 to 7 sockets in a cluster to replace those legacy 300 watt high bay porcelain reflector bulbs and use the cheapest 60watt type. Easy to replace a dud, spreads heat out the cheap way. He bought a few of those expensive 300 watt equivalent things the size of a large can of beer, the electronics are cooped up in the hot horn of the reflector. All the light comes out the sides little below, then the three terminal driver unsolders it self and out comes the magic smoke.
To heck with dimmers, just have mood lighting and work level lighting separate. However the dimable lights are better hardened against spikes that’s why they are more expensive.
I cringe at GE products but the glass LED bulb has got to be worst thing ever. Finally when LED lights are unbreakable they reinvent the breakable glass idiom.
In my experience, a lot of LED bulbs last MUCH shorter than even 1000 hours. More like 100-200 hours. But I haven’t found a pattern, it’s not that the cheaper ones die sooner.
One thing I haven’t seen mentioned in the comments is the annoying high pitched sound that LEDs often emít. Recently I bought a rather expensive Philips bulb because I expected it to perform better, last longer, look better. But sadly it looked very greenish and it had an intolerable high pitched noise. It was expelled to the shed. I have been told that dimmers can make the bulbs noisy, but there was no dimmer involved.
Yet another thing that is not mentioned in the article or the comments is the bad smell that some bulbs emit, probably from the electronics. Not as bad as many CFL bulbs though which send out a sharp acetic acid like smell.
Good article. More autopsies needed. None of my 15Khr+ projected LED have made it. About half have had LED failure and the other half driver failure. Surprisingly to me only a couple due to electrolytic death. Thats on the 120VAC current. Ones designed for 12-48VDC arena tend more towards LED failure roughly 75%. Which really isnt saying much due to their simplistic driving Often a resistor and maybe a zener.. 10% due to mechanical stress and poor manufacture/design. Then there’s the cheapos (120VAC) from Wallys that have so far not lasted 2Kh and all but one have been LED failure. The one excluded having been term!inated by 40KW genny and overzealous newbie *crunchy.
Boy there is a lot of talk here. I have not read them all yet. I have a 12 volt solar power system in my house with 6 12v deep cycle batteries and a 2000 watt inverter for my furnace and fridge. Every room has 12v LED lights and power plugs and switch and motion detectors. So when the power goes out I have lights on. It is really cool. I have 1000 watts of solar panels that have been up for over 10 years now. ( And NO solar panels have not gone down in price as far as Dollars go). The first solar panels I got cost me 45$ for 20 watts and today a sale price on solar panels cost over $230 for 100 watts.
I have dropped the voltage and wattage to each light on the 12v system. I did have to add a bit more LEDs to get the same brightness but well worth it. And the common rooms have little night lights that come on. I really feel that the LEDs lights that you buy are set at to high of voltage & amperage and I really think they are getting to hot and are to bright. So with this lighting system the LEDs I have will last a heck of a lot longer. With these they have been going for about 5 years or longer for some. And only had to replace 1 light to date.
$230 for 100 Watts??? Where the hell do you buy your Panels? The normal sale price for the standard 230W panels is $180 to $220.
The issues here are above my paygrade, but aren’t LEDs much more sensitive to being turned on and off? I seem to remember this was an unforeseen issue that was greatly underestimated when replacements for incandescents were originally introduced. People have been trained to save electricity by turning lights off as often as possible. It’s counterintuitive that this would shorten the lives of bulbs. I’m not sure, but maybe there would be significant savings by keeping these bulbs lit? Untraining people from habits built over a couple of generations is a big issue.
This is what my Dad would tell me 30 years ago about the fluorescent bulbs! I have not heard it about LEDs, though that doesn’t mean much.
I have a fixture in the laundry room that has a Leviton motion sensor/photocell switch that bleeds residual current. The first generation Led bulbs (40w equ.) I tried would always stay on, at a lower, but noticeable level. They burned out after about 9 months. The current generation LED bulbs (60w equ. Feit) stay dark when off but are only last 3-4 months. The last time I replaced them, I put one LED and on one 60w equ. Sylvania halogen (48w). The halogen lasted one month longer than the Led! :(
The CFLs that I have attached to X-10 modules flicker when the module is “off”. I guess it is because of module needing to have a small current available to detect if the lamp is physically turned on.
My great grandmother told me that about tungsten bulbs, honestly! I think the idea was they used more power being switched on and off than by just leaving them on. The minimum safe “on” time she never told me. And far as I can tell she switched them off when she wasn’t using them just like everyone else.
I think Consumer Union (i.e. Consumer Reports) did a study on that… The inrush current of an incandescent bulb lasts only about 1/5 second. So, the amount of power consumed in that time isn’t much. And back when they did the study, most residential power meters (spinning disk type) didn’t react fast enough to meter that tiny surge, so it wasn’t reflected in the power bill. It is the thermal shock of the inrush current that does blow most incandescent bulbs. I have on a shelf a bag of small disks intended to be inserted into the bulb socket before the bulb is inserted. At first I though they were diodes, but a DVM didn’t show that, so they may be more like an absorber to limit the amount of initial current. Either way, they are fragile, I broke several, screwing the bulbs in too tight.
I’ve seen those. I think they are negative temperature coefficient varistors, which start out at some tens or even hundreds of ohms, then drop down to a few ohms, which drastically reduces the turn-on surge. And incidentally, they do retain some resistance, which reduces the average current as well. I don’t have any tungsten lamps to measure right now, but last time I measured one, the cold resistance was around 30 ohms, which would indicate a 400 W surge. The surge failure IS what makes most incandescent lamps fail at turn-on, but this isn’t as big a factor as you would think. The way tungsten lamps fail is, because the ends of the filaments are attached to metal supports, the middle is always hotter than the ends. Tungsten evaporates from the middle, causing it to get thinner over time. By the time the bulb fails at turn-on, it’s because the middle of the filament has gotten thin enough that it melts. But by the time this happens, the bulb is already near the end of its life span anyway, so reducing the surge may not have that much effect.
Facinating article. I knew they limited the lifespan of products in order to keep prices down and the consumer buying more often – but that was for household appliences, not simple lightbulbs! I don’t know much about the intricate technical issues at hand, but I had new ceiling lighting put into an old house I bought just over a year ago; out of 38 recessed LED trim lights I have (I think 60watt equivalent) only 1 started the deathly flicker after 1 year. All are (apparently) dimable but I did not install dimable switches. I probably used that bulb (1 of 4) for about 2000hrs a year. Additionally, a 40watt equivalent loose ‘globe’ LED bulb I have also just started flickering, probably after similar 200hrs. I am definitely more educated now when looking to purchase replacements. Thanks.
I grow with house hold leds I use use a couple filament Leds and six 1600lm 16w 100w eq the filament leds 50% failed in a month but have great spectrum for seedlings and the 100w got really hot so after a year I took them apart and installed heat sinks with fans which only draw 12v .1A and its been running for another year to date I would say the the first year I lost 15% of the lumens and the second year they lost 5% more heat is definitely a killer in 100w house leds oh ya my lights run 24/7 so they ultimately never get rest but are well cooled
A product line of mine uses a small LCD with RGB LED backlighting. After several years in the field the blue segment has a greatly reduced output (whereas red and green are unaffected) and the display appears yellow (we call it “jaundiced”) when it is meant to be white. :( The only fix seems to be to reduce the average current (to extend the LED lifetime). The display is still very legible with the reduced current, but there’s nothing I can do for the numerous units already in the field.
Maybe a side-topic, but about the e-waste factor of discarding all these LED bulbs and associated electronics? Its a no brainer that they cost less in usage/consumption for the end user, but seems to be a bit of a throw-away, and part for part (environmentally) compared to a tungsten filament they must a have much larger carbon footprint. We don’t have a good ewaste recycling here in New Zealand either (expect any ewaste gets shipped to 3rd world countries to be manually pulled apart in less than ideal situations).
I have to say as a prolific dump diver and hoarder it does make me think that buying a tungsten bulb produces less waste, even if I pay more for my (hydroelectric) power than a LED bulb, even if I turn off lights religiously…
why not mention that incandescent light bulbs used in traffic lights actually lasted way longer as they were built to do so?
They lasted longer because they ran at a lower temperature. And therefore also used more electricity.
Which ironically solved another problem that has surfaced with LED traffic lights: the lenses keep freezing over and the electronics are dying of moisture because there’s not enough heat to keep everything dry.
Known issue with blue LEDs, I have also seen the same problem on frequently used keyboard lights (normally the Scrl Lock) whereas Caps and Num are affected less severely. Changed out all the duff ones on my laptops and they are a lot better now and plus don’t nuke my sleep pattern. Incidentally defunct but weak emitting LEDs used on UPS’s make great varicaps at least when I tried them.
Blue OLEDs are not much better, the compound used is IIRC an anthracene derivative and it burns. You can actually get a display from an old phone and see how often they keyboard has been used!
Watch out when using an LED (or other clear case diode) as a varicap. If light gets to it, that add “noise”.
Someone write about using different types of guides as varactors in s VCO forty years ago, and had odd problems with unwanted hum. Finally he realized he was using a diode in a case that would let lighting, and his desk lamp was modulating the diode with 60Hz from the AC line.
Always with “efficiency”, “carbon emissions”, etc. Yet seemingly always based on *after* it reaches the consumer. E.G. LED bulbs are generally heavier than incandescents, more weight shipping = more fuel. E.G.2. Silicon fabrication, plastics fab, etc. = power, nasty chemicals, etc. (majority non-recyclable) E.G.3. Epoxy in PCBs offgassing, plastics offgassing, electrolytics offgassing, etc. E.G.4. Replacing 2 incandescents, each with 500 remaining hours, is equivalent to one bulb’s winding up in the landfill “new”/”unused”… do this over thousands of households, now does it still seem greener than riding out their lifespan? The list goes on.
Well, no, we really don’t care, because all those things are pretty much negligible. Run incandescents until they burn out, and leave the ones in the closets alone. Electrolytic outgassing bothers you?
Incandescents aren’t recyclable. LEDs are repairable, although I haven’t had any die yet. I take CFLs apart, recycle the tubes, and repurpose the electronics. The inductors are good usually.
Don’t forget Jevon’s paradox: because LED bulbs use less electricity, people buy more lights and put them in places that serve little purpose, using them in less efficient ways because it doesn’t cost them any more than what they were paying before.
We use 1 watt task lights now instead of 60 watt table lights. Nobody has complained. I leave a couple night lights on, though, figure out to about 16 cents a year as my contribution to global warming.
When it “seemed” like on of the first CFL lamps I used didn’t lived up to it’s longevity I started using a sharpie to write on the installation date. Over all I can’t complain about the CFL and LED lamps I have installed Very few failures.Despite my usage habits are far from the conditions that the predicted longevity for service life. For the manufacturing facilities to remain in place to serve both current consumer, there has to be a predictable failure and cash flow fate. This is an issue I’m wringing my hands over.
If you think it from the sustainability point of view, would it be better to produce fully recycleable product lasting over 100 years or 100 products containing hazardous waste and is almost non-recycleable that lasts only one year?
I’ve heard that in the People’s Republic of California that apartments have to have a special bulb socket that only LEDs fit. Of course the special LED bulb costs 10X more than a normal one because it’s specially made for that market, but that prevents people from wither stealing them when they leave or putting incandescents in them.
Well, I think a standard fluorescent tube would be very recyclable, glass, argon, phosphor, alumin[i]um rings at each end, brass contacts, a tiny bit of tungsten, and a drop of mercury.
It’s hard enough to recycle anything these days, because the Chinese won’t take it any more. I doubt the phosphor or argon in fluorescents gets recycled. It’s treated as hazardous waste because of the mercury, then the rest is shit-canned.
The whole recycling fiasco is now, well, a dumpster fire. I don’t see any politicians getting enthused about it, either.
I have 2 let bulb timing 24/24 7/7 365/365 since 4 years working perfectly but they are behind a battery and a inverter. Exactly same bulbs directly plugged on AC die between 1.5 and 2 years. Then I suppose what kill let bulbs is the instability of the AC line with some nasty peak.
If they just quit, it’s not LED wearout; the driver has fried. Either bad soldering, heat, or line spikes.
What about LEDs inside Cars? If have been told LED daylights used in cars are never going to fail. Yet i see many dead lights in traffic.
Yes, LEDs are a good match for automotive. Most automotive LEDs (for dome lights, for example) use three LEDs in series, with an additional resistor. Oh, and a bridge rectifier. No capacitor, no switching supply. The only challenge, really, is that they’re often subjected to temperatures in the 120 deg F range.
I doubt they have need for a bridge rectifier. A constant current driver would be nice, since they have to deal with voltages from 12 to 14V and higher spikes.
Early LED taillights (GM mostly) were poorly built and had soldering issues. Replacements were ridiculously expensive, of course, although they could be repaired easily.
Ah, those must be aftermarket replacements for socketed bulbs, where you never know which side is ground. Probably not the best engineered or built devices.
Automotive systems are harsh – you can have hundreds of volts in random spikes, or load dump conditions when something in the system fails. Filament bulbs don’t care – LEDs just fail unless there’s a transient voltage suppressor device in-line.
The whole replace incandescent light bulb with X (led’s, compact fluorescents, etc) is a bunch of crap and reeks of someone raking the public over the coals yet again. First once the electricity crosses that meter (becoming MINE because now I have bought it!) it shouldn’t be ANYONES business what way it is consumed by my devices! Be it a direct short to ground, an hot dog cooker, sock warmer or heaven forbid a light bulb! Bulbs used to cost 25 CENTS or so each, often 4 cheapo branded at 99 cents for 4 compared to the LED ones that can cost 4 bucks to over 20 dollars EACH ! That’s a lot of old fashioned bulbs folks, try replacing several rooms of lights such as when moving into an apartment (no one leaves LED bulbs behind) and you could spend HUNDREDS on what would have cost under 20 bucks with old style bulbs. AND these are supposed to save me money??? Weird math for every day guy cause the problem is up front costs are harder to pay who cares if the utility bill is a dollar or 5 dollars less each month when I can only afford bulbs in a few sockets abd those cost me 100 bucks TODAY out of this paycheck?? Again inferior lighting at 100 to 1000 times the unit costs to save me 1000 dollars utility cost over the 90 YEAR supposed life of the bulb! That’s a RACKET folks You are being swindled into buying LED bulbs to support a lower quality product! Besides I want to see a LED bulb bake a cake in an “easy bake oven”! Bet that takes a while! Think about it if LED bulbs were the miracle lighting innovation they are made out to be why OUTLAW the old style bulb ? If leds were that much better then incandescent lamps would go away on there own like kerosene lamps did in the past!! Remember after electricity is bought by me Its mine do not tell me what I can and cant use it for!!
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I have a bunch of dollar store and cheap Lowes bulbs. Nice color, no flicker, no RF noise, and still running. I wouldn’t use them in a glovebox, true…
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