That 60W-equivalent LED: What no one will tell you

http://www.edn.com/electronics-blogs/led-insights/4423570/That-60W-equivalent-LED--What-you-don-t-know--and-what-no-one-will-tell-you-

by Shivetya • 13 years ago

149 180 13 years ago

edn.com

andrewcooke3• 13 years ago

i'm confused. how can they be efficient if they get hot? are they less efficient than the coiled tubes? if so, why are they an improvement?

edit: how can they be more efficient than cfls if they get hotter? how are the cooler cfls wasting energy? you can't just "lose" energy - it has to go somewhere. and normally for losses, it's heat.

benjamincburns6• 13 years ago

They're more efficient, not perfectly efficient.

Edit to your edit: The amount of heat is actually quite small in comparison to a CFL. The temperature they're talking about is the die temperature. LED dies are tiny, so even though they can reach high temperatures, there's much less heat (waste energy) generated.

masklinn2• 13 years ago

And more problematically, heat severely degrades them (an incandescent bulb will also get extremely hot — as everybody who tried changing a just-blown bulb will know — but for the most part the heat will not significantly degrade it and lower its life expectancy)

sean13013• 13 years ago

The parts that generate the lion's share of heat in an LED bulb are tiny tiny tiny, and so they can get very hot with much less energy. They generally have chunky heatsinks, but still you can only draw heat away from a point the size of a head of a pin so fast.

kijin3• 13 years ago

A regular light bulb converts about 2% of its energy input into light, and 98% into heat. For a 60W light bulb, about 1.25W is converted into light and 58.75W into heat [1]. It's incredibly inefficient, and the filament can reach temperatures of over 3000K. (Ever wonder why CCFL lamps have their colors expressed as temperatures like 2900K? That's the actual temperature of a filament with the same color.)

A 60W-equivalent LED lamp uses 6-8W of energy. Assuming it converts roughly the same amount of energy (1.25W) into light, the remaining 4.75-6.75W needs to be converted to heat. That's about as much thermal dissipation as a low-end laptop CPU, but concentrated in a much smaller area and with a much less effective cooling system (it doesn't even have a fan). 85 degrees sounds about right.

[Edit] Still, 85 degrees is nothing compared to the extreme temperatures that a filament in a regular light bulb experiences. It's only a problem because the LED chips aren't made of carbon or tungsten like filaments are.

[1] https://en.wikipedia.org/wiki/Incandescent_light_bulb#Effica...

andrewcooke3• 13 years ago

i'm not comparing LEDs with incadescent bulbs, i'm comparing them with the coiled tubes - cfls. these things - http://en.wikipedia.org/wiki/Compact_fluorescent_lamp

[i thought that was obvious - are you trolling?]

InclinedPlane2• 13 years ago

Ever wonder why a "Halogen" light bulb has that name? Well, what happens if you try to create a very bright incandescent lamp is that when pumping so much electricity through a filament and heating it up to incredible temperatures you'll actually start to evaporate the filament. This is a common failure mode for incandescent bulbs, a part of the filament will get thinner due to evaporation and then the reduced thickness will increase resistance in that section, accelerating evaporation and eventually causing a break. But if you put a small amount of Bromine or Iodine gas (halogens) inside of the bulb, and a small amount of Oxygen, then the evaporated metal will form a Tungsten OxyHalide gas which will then redeposit Tungsten metal through an electro-chemical reaction back onto the filament, increasing the filament's longevity even at very high power levels.

phaker• 13 years ago

A regular light bulb converts about 2% of its energy input into light, and 98% into heat.

This isn't relevant to your argument, but that actually isn't true, that figure is about 6~8 percent.

* The "luminous efficiency" as commonly reported is just the lumen/W luminous efficacy divided by the peak value of 683lm/W. The value of 683lm/W is the peak of human eye sensitivity curve and occurs at 555nm. The only light source that can achieve 100% "efficiency" by that measure is a 100%-efficient radiator that emits monochromatic 555nm (bright green) light, the best a perfect white light source can do is about 37%. (see [1])

* That "perfect white light source" would be a 100%-efficient radiator emulating the Sun spectrum bandlimited to visible light (zero infrared, uv and no other losses).

* It's possible to make a light source that appears white to human eye and is more efficient than that by emitting mostly at wavelengths the human eye is more sensitive to, and emitting less at wavelengths it's less sensitive to. That's part of the reason why manufacturers often offer CFLs with high efficiency but poor color rendering and lower efficiency but higher color rendering. (And don't get me started on the color rendering index.)

* That definition of "efficiency" is obviously not what most people think it is when they hear that word (useful work / total work spent), some prefer to call it "luminous coefficient". But it's not all lies, it was defined that way because it's easy to compute and understand and because this is the value of interest if e.g. you're making a LCD backlight or if you're designing an interior lighting setup.

[1] https://en.wikipedia.org/wiki/Luminous_efficacy

ars13• 13 years ago

how can they be more efficient than cfls

They are not more efficient than CFLs. It is interesting that you think they are - I guess the marketing is working.

Now, you might come across some LEDs that on the surface appear to be more efficient, but actually they are misleading you. Those efficient LEDs have worse color accuracy than CFLs, so you are not comparing equivalent products.

LEDs do have room to improve, so they may get more efficient than CFLs, but they are not there yet.

jcampbell1• 13 years ago

CFL's also get hot, but the heat is on the coiled glass tube, so the heat and light radiate from the same place. Because the coil is the radiator, they ventilate heat naturally. In order to trap the heat in a CFL, you would need to design a fixture that doesn't let light out.

The problem with LEDs, is you need a metal radiator positioned to not block the light. In a recessed fixture, the heat can get trapped.

Florin_Andrei6• 13 years ago

They don't get "hotter" overall. The problem with LEDs is that most of that waste heat is produced in a tiny element - the actual LED chip - which is difficult to cool down because you can't surround it completely with heat sinks. The meager heat sinks you can put on the back of the chip are not so well connected thermally with the environment.

A CFL has a much larger volume to produce that heat, and a much larger surface area to radiate it; and even if it got very hot it wouldn't care that much. A LED is a tiny speck of semiconductor that bears the brunt of a lot of energy, and it's not rated for operating at high temperature.

It's like normal sunlight warming up the palm of your hand versus sunlight focused to a point by a palm-size loupe - it's the same total energy, but one is nice and warm whereas the other can cause serious damage.

pwg• 13 years ago

i'm confused. how can they be efficient if they get hot?

The reason is due to the balance between heat generated and heat dissipated into the environment.

The bulb could convert 99% of the input electrical energy into light, and only 1% into heat. So for a 100W bulb, that would be only 1 watt of heat.

But if the heat dissipation system (i.e., the cooling system) can only dissipate 1/2 watt of heat into the environment over the same time span that the bulb is creating 1 watt of heat, the excess 1/2 watt of undissipated heat will build up over time, making the housing hot to the touch.

Benferhat• 13 years ago

tl;dr: LED bulbs get too hot, lowering their life expectancy. Manufacturers need to include cheap thermistor circuits, which automatically dim the light to a safe thermal equilibrium.

benjamincburns6• 13 years ago

Consumers need to be educated, too. Anyone using an A19 in a can-style fixture is wasting energy by lighting things they don't need lit. Use something directional like a PAR or a BR, and you can reduce the amount of wattage consumed to light a given area.

Further, LED manufacturers design their directional lamps with these applications in mind. See the spiral pattern [1] on the heat sink around Lighting Science PAR bulbs? That's designed to use the thermal differential to create a nice air flow up into the fixture so that it may be used in a recessed or other partially-enclosed fixture.

1: http://www.1000bulbs.com/product/100560/LED-PAR3011HE25WW.ht...

Lightbody• 13 years ago

It's not that simple, sadly. My house has 100+ canned recessed lights, all of which had been filled with Sylvania 50W Halogen PAR30 & PAR30LN bulbs. I have been desperately trying to find a replacement LED that matches the same warmth and color.

This bulb claims to be the exact replacement:

http://www.amazon.com/gp/product/B00467E3LA/

But yet this one and others that have similar lumens, temperature, and equivalent watts all don't even get close to the warmth that the halogens produced.

Fortunately, I found a cheap alternative:

http://www.amazon.com/Philips-424374-7-watt-Household-Dimmab...

It's the A19 40W that the article cautions against, and it looks slightly less sexy in the recessed can, but the color almost exactly matches the halogens I have (except when dimmed -- nothing can match the fireplace-like glow).

What's weird is that the lumens and temperature for that bulb aren't even close to what the halogens claim, but they look almost identical. Which has made me wonder if this switch to LED is way more complex than just those two measurements :P

Pxtl4• 13 years ago

It's a light bulb.

A light bulb.

This isn't a car, which you expect to require some expertise. It's not a furnace that will be primarily handled by an HVAC specialist. It's a light bulb. Consumers have a reasonable expectation that devices like this Just Work. If the device fails to meet its promised service-level without a dozen asterisks in its usage? It's not meeting its intended purpose and it's defective.

Consumers should not have to meticulously research every small purchase. Simple, small purchases of replacement parts should not require reading a 10-page instruction manual of 6-point font, especially since you didn't get this manual until after you got the damned thing home.

By allowing manufacturers to sell these defective devices, we don't just hurt consumers, we hurt the environment with unnecessary waste of electronics, and we hurt the real, quality manufacturers who want to sell good stuff but can't because there's no way to tell consumers "all the other crap on the shelf will break in under two years and we won't" so they end up getting crushed by people who cut corners.

trebor• 13 years ago

Thermistors will help, yes, but the manufacturers need to design better enclosures for LED lightbulbs. They need fair air circulation for that heat sink to work well. And in recessed lighting it's the worst.

It's a design issue of the bulb, sure, but especially the fixture. LEDs aren't friendly to high heat like incandescents are, and most light fixtures have been designed with complete disregard to the heat of the fixture—so long as it won't start a fire.

Florin_Andrei6• 13 years ago

It's difficult.

The CFL has a huge volume and a huge radiating area for the heat, and that area is well-connected thermally with the environment. Plus, it can operate at higher temperatures anyway.

The LED active element is a tiny chip of semiconductor material. All that heat is dumped in a tiny volume, and you can only put a heat sink on its back. Plus, the heat sink is close to the fixture and therefore necessarily hampered in its function.

It's not an easy problem to solve. If we think pie-in-the-sky solutions, perhaps a re-design of the connectors and fixtures might help - if you made a connector that was designed to take heat away from the bulb, that would help a lot; the whole fixture would become the heat sink.

crazy1van• 13 years ago

I doubt customers will react well to their bulbs changing brightness levels on their own.

bronson• 13 years ago

The incandescents in my kitchen change brightness every time the microwave turn on. I can live with it.

(It's old knob & tube wiring. Electricians claim it's safe)

tonylemesmer• 13 years ago

If the thermister circuit is installed they'll be dimmer. Either way, the customer is still disappointed. Shorter life or dimmer bulb, depends which the customer is more concerned about. Adding the circuit changes nothing.

fooqux2• 13 years ago

Not all LED lightbulbs are created equal. I've been watching some guy on Youtube do various teardowns and tests on various brands, and it's been enlightening. His channel is at http://www.youtube.com/user/electronupdate

Also, isn't the phrase "What you don't know, and no one will tell you" oxymoronic? I suppose "what you don't know, and only I will tell you" doesn't have the same ring to it.

benjamincburns6• 13 years ago

Well there goes my day... Thanks for posting that link!

InclinedPlane2• 13 years ago

While you're at it:

http://www.youtube.com/user/bkraz333

http://www.youtube.com/user/eevblog

http://www.youtube.com/user/Afrotechmods

tracker12• 13 years ago

It's fairly obvious, that you and the guy that runs the channel in question are witches... prepare to burn!

Seriously though, this is pretty cool... I am fairly surprised that there hasn't been a DC standard for lighting fixtures come into play yet... Which could be much more effective in terms of cost over time, and temperature control. Given the shear number of wall warts, and other fixtures common in the home, it would make sense for a more common interface for DC (especially low watt)... USB seems to be becoming that standard, but for lighting, and safety for internal wiring a new standard is probably needed (or an old one revisited).

Osiris• 13 years ago

Given that nearly everything in a home uses AC-DC converters, I'm also really surprised that there isn't (that I know) a standard for a whole house DC jack that can supply common DC voltages, removing the necessity for all devices to have their own AC-DC transformers.

nknighthb2• 13 years ago

A universal DC standard isn't a silver bullet. Different circuits/devices and different batteries require different voltages, so there are still conversion steps to go through. Not so long ago when linear regulators (which tend to be better at producing heat than desired voltages) were typical, this would have just meant another wall wart for most devices. Even now, it still means some added cost, complexity, size, and weight.

Florin_Andrei6• 13 years ago

"What you don't know" refers to the present moment.

"And no one will tell you" also seals it for the future.

fooqux2• 13 years ago

Sorry, I should have elaborated. It's oxymoronic when it's the title of a paper which entire purpose is to tell you what it just said no one would ever tell you.

dkarl• 13 years ago

Also, isn't the phrase "What you don't know, and no one will tell you" oxymoronic? I suppose "what you don't know, and only I will tell you" doesn't have the same ring to it.

It's a cheap trick of appearing honest by using impossible hyperbole. The meaning of the statement is so obviously not equal to its literal meaning that if the writer is challenged over the honesty of it he could plausibly defend it by saying, "It feels like this fact is not being communicated sufficiently to consumers who are not familiar with LED lighting." In other words, it's a way to manufacture compelling copy without needing any facts to back it up.

JackFr• 13 years ago

This read to me like an ad for CFL's. Real shortcomings of CFL's are dismissed with a hand wave, while LED's get the full local news style sensationalism: "Are your LED bulbs killing you? Story at 10."

gagege• 13 years ago

Nah, I didn't read it that way at all. The article clearly states, several times, that LEDs consume less power and that there are better LEDs out there. Also, the article basically equates CFL and incandescent bulbs. If they were trying to sell CFLs why would they do that?

colanderman• 13 years ago

It gives a simple design enhancement for LED bulbs at the end of the article to fix the problem outlined. So I think not.

dfc• 13 years ago

Or it reads like an advertisement for thermal management technology inside of LED light bulbs:

"Ed Rodriguez [the author]...formed OptoThermal Technologies to focus on thermal management technologies related to high-power LED lighting."

http://www.edn.com/user/ed%20ro

ams6110• 13 years ago

Thanks for the warning. Time to restock my cache of incandescents, before they are completely unavailable anymore.

carlob3• 13 years ago

No need to do that, you can still use CFL and they are not being phased out.

maw2• 13 years ago

Why would anybody want to use CFL? Is it more for the migraines or for how they make everything look sickly?

_red• 13 years ago

What if you don't want to deal with the toxic mercury gases?

melling2• 13 years ago

Generally speaking, you are looking at this incorrectly, and if enough people share your views, it impedes progress. By voting with your wallet on newer technologies you help to fund further advances. Granted, it takes millions of people to make a difference but I would hope that the HN reader would be leading the way.

carlob3• 13 years ago

Unfortunately there are also plenty of bar owners who are voting for carbon filament incandescents with their wallets. They are even less efficient than tungsten, they last less and the glass gets black from soot, but they look oh so hipster.

Florin_Andrei6• 13 years ago

I bought a huge box of big CFLs when a nearby store went out of business, for something like less than $1 a pop. Not quite a lifetime supply, but I am definitely not going to be an early LED adopter.

adestefan2• 13 years ago

The same thing happens to incandescent bulbs. If you put a regular light bulb in an enclosed housing it's going to burn out fast due to the excess heat, too. This really is a baseless attack.

tsotha2• 13 years ago

Yeah, but when an incandescent bulb burns out it costs, like, seventy cents and not twenty bucks.

Pxtl4• 13 years ago

IANAL, but it sounds like there are a dozen class-action lawsuits waiting to happen here. Consumers have the reasonable expectation that a light bulb reach something vaguely approaching its promised useful life in any fixture that is supposedly compatible with it.

maxerickson• 13 years ago

This mentality says that you can't put a screw base on some technology that you can easily say is not for use in enclosed fixtures.

In some sense, I think you are arguing that your oven should be compatible with gasoline (cause hey, you can put gasoline in a container that will fit in an oven). Of course you aren't, I just think you are probably headed too far in that direction. I guess I'm willing to make consumers do more than make sure they fit together.

lotsofcows• 13 years ago

Oxymoronic titles ftw!

Hermel• 13 years ago

Also, regardless of what it says on the package, the light won't be as warm as that of a classical light bulb. For a cosy light, you need to get a classical bulb or halogen.

nodata• 13 years ago

So is there a table of which manufacturers use thermistors?

ajcarpy2005• 13 years ago

It looks like we're gonna need some innovations in light fixtures which have better heat flow/sinks.

dangrossman4• 13 years ago

I have dozens of Cree-brand LED bulbs in my home (they're the uber-cheap brand Home Depot carries, yet always very favorably reviewed). Their packaging carries no warnings against use in totally enclosed fixtures, and I have several in such fixtures in bathrooms. They also come with a 10-year full replacement warranty. Some are now about two years old, and none of their bulbs have failed or even become too hot to touch.

I have a feeling this guy's overstating the problem. Perhaps because he's in the business of patenting thermal protection designs for bulb manufacturers.

Shivetya• 13 years ago

its not the bulb that gets warm, after having one on awhile take it out of the fixture and check the base of it.

I have two in tulip style fixtures where the bulbs point down, they don't last long but receipts are a wonderful thing. Eventually I think the big box store I get them from will change their return rules

jamesaguilar2• 13 years ago

As long as they have a ten-year replacement guarantee, I guess it doesn't matter as long as it's not a fire hazard.

loginx• 13 years ago

I've noticed the opposite pattern in my house. Ever since we bought the place, we noticed that occasionally we would semi-randomly get a very fishy smell coming out of our staircase, and couldn't find the cause.

After putting my google-fu to use, I realized it was the plastic casing of a small light fixture in the staircase that was getting very hot and slowly melting around the incandescent bulb.

I've replaced the bulb with an LED bulb several months ago and I've checked the base of the socket, the fixture, and the bulb after hours of use, and all three are barely warm to the touch at all.

I suppose it may depend on manufacturing quality, or as the OP article mentions, airflow.

squidfood• 13 years ago

And I had one in a recessed fixture burn out in the first hour. I'm definitely waiting until there's some stability in expectations or labeling.

Lagged2Death3• 13 years ago

Some are now about two years old...

Those Cree/Home Depot bulbs were brand new this spring (2013). If you've got LED bulbs that have been going for two years, they're probably something else.

http://www.cree.com/News-and-Events/Cree-News/Press-Releases...

dangrossman4• 13 years ago

The oldest ones are whatever store brand Home Depot dropped under $15 first. Ecosmart maybe? That's when I started replacing CFLs. I switched to only buying Cree when those dropped under $10 too.

allertonm• 13 years ago

The Cree bulbs - at least the ones in Home Depot in Canada - actually do have a warning about using in enclosed fixtures. It says (to my recollection) "Do not use in enclosed fixtures with other types of bulbs". So my take on this is that they are supposed to be OK providing you don't mix the Cree LEDs with CFLs or incandescents in the same fixture.

I am trying them out in some enclosed fixtures, too early to tell how that will work out.

dangrossman4• 13 years ago

I've uploaded a photo of both sides of the Cree product packaging here in the US. It's the same for 40W and 60W bulbs. There's no notice about not using it in any type of fixture. The only thing it says not to do is expose the bulb directly to weather.

http://i.imgur.com/p9W3SXG.jpg

http://i.imgur.com/gbtbX8L.jpg

refurb• 13 years ago

Wow! I actually liked this article. Taught me something I don't know, made a nice factual argument without using hyperbole.

A great example of the kind of article we should see more of on HN.

tytso• 13 years ago

There are some LED bulbs that are explicitly rated for use in enclosures with no ventilation. The other thing to pay attention to is whether the light dispersal pattern is pointed mostly straight down (i.e., for a recessed ceiling lighting fixure) or omni-directional (i.e., for a sconce or a table lamp). Reputable stores will make this clear --- and yes, it's a bit more complicated than just grabbing a random 100W incandescent bulb. For example:

http://store.earthled.com/collections/led-light-bulbs-suitab...

cjensen• 13 years ago

The point of the linked article is the bulb will not last very long when hot. The article never said it wouldn't work.

adestefan2• 13 years ago

No bulb will last very long when hot. This isn't something new.

grogenaut2• 13 years ago

Don't Bury the Lead Dude.

I've seen senate reports that take less time to get to the point about safety warnings. TL;DR: Many leds aren't meant to be in unventilated can fixtures and will either burn themselves up, reduce lifetime, or worse start fires. At least that's what I think I got out what was mainly a lot of talk about other types of bulbs.

vacri3• 13 years ago

Given this topic, I would have gone for the alternate spelling in 'don't bury the lead'...

grogenaut2• 13 years ago

don't burly the lead?

pkulak• 13 years ago

I still have no idea why an led bulb is better than CFL for home lighting. From what I can tell, people just like new stuff.

dangrossman4• 13 years ago

I still have no idea why an led bulb is better than CFL for home lighting

* They use 30-40% less power, costing you less to operate

* Cheap CFLs commonly had ballasts that died in 1-3 years despite higher life expectancy claims on the packages; LEDs are backed with 10+ year warranties

* CFLs burn out quickly if used in fixtures that are turned on and off frequently

* LEDs don't flicker/strobe like fluorescent lighting

* Virtually all LED bulbs work in dimmers, not just more expensive specialty ones

* Cheap LED bulbs don't produce bluish light like cheap CFL bulbs

mrgriscom• 13 years ago

and they rise to full brightness immediately... and they're indestructible... and they're not filled with mercury...

ars13• 13 years ago

They use 30-40% less power

That isn't true. Only LEDs with poor color accuracy are more efficient than CFLs.

CFLs burn out quickly if used in fixtures that are turned on and off frequently

People claim that, and it makes sense, but it doesn't actually happen. Modern CFLs do just fine.

LEDs don't flicker/strobe like fluorescent lighting

Florescent lighting does not flicker, and cheap LEDs actually flicker more than CFLs.

Cheap LED bulbs don't produce bluish light like cheap CFL bulbs

Walmart CFLs cost $1 and have excellent color. It doesn't get cheaper than that.

It seems you made your mental list more than a decade ago and have not updated it as CFLs have gotten much much better.

Florin_Andrei6• 13 years ago

Hm. I went to the store and compared CFLs and LEDs for the same lumen rating. Their electrical power was about the same.

Flicker - I actually have an Ikea LED lamp that has two active elements inside (2 LEDs). The supply is a simple 12 V AC transformer. I suspect the two elements are connected in a push-pull (anti-parallel) circuit, because they've started to flicker recently - if mounted push-pull and not equal in terms of brightness, that would explain it.

I thought CFLs produce more of a weird green hue - at least that's how both my eye and my cameras see it. At any rate, the main emission line of Hg is smack down the middle of the green part of the spectrum.

xaritas• 13 years ago

Very high failure rate (including one case where my wife called the fire department because something was burning in the house and she couldn't identify it), warm up time, and has to be treated like HAZMAT after it has completed it's six months of duty—indeed, what's not to love about CFLs, and why should I bother checking out an alternative?

Yes, I purchased my LED bulbs in anger. We'll see if I've been had.

ars13• 13 years ago

I've had that too - fire department and all.

The UL has now required end of life circuits in all CFLs so this won't happen again in new CFLs. (And new is relative - this regulation came about a few years ago.)

apendleton• 13 years ago

At least in theory, they're more power-efficient and last longer (though, as this article suggests, that may or may not be true). Things that are pretty much universally true, though: they turn on faster, have no warm-up time like most CFLs, are more often dimmable, and typically have better spectral distribution (though not as good as incandescents), which tends to make them less likely to impart the sickly cast that things lit with CFLs take on.

Florin_Andrei6• 13 years ago

No mercury inside.

jwr2• 13 years ago

I've spent a lot of time recently working on my own LED lamp designs. Heat dissipation is indeed the biggest problem, the second being the cost and complexity of interfacing to an AC network of 230/110V.

I think new kinds of fixtures will need to be designed, as well as new standards for DC distribution within the house (I am trying out 48V and 24V). Retrofitting existing infrastructure with LEDs makes no sense: we get wasteful, fragile and inefficient systems.

kalleboo2• 13 years ago

as well as new standards for DC distribution within the house (I am trying out 48V and 24V).

This is something I've wondered about for a while. Everything in my home aside from a few kitchen appliances is now running a AC<>DC converter. At what point does it make more sense to run DC circuits in the home? Would the gauge be a problem to run enough DC power for a desktop PC, a TV, and a ton of LED lights?

jwr2• 13 years ago

I think you need to strike a certain balance: for longer stretches of wire and higher wattage AC will work better. What doesn't make sense is building tiny switching power supplies into every lightbulb.

I was planning to use a power supply for every group of lights — e.g. one for the ceiling, one for under-cabinet lighting, etc. That way you don't have to run long stretches of wire with DC, and yet you don't have to build lots of tiny low-efficiency converters.

Perseids• 13 years ago

Retrofitting existing infrastructure with LEDs makes no sense: we get wasteful, fragile and inefficient systems.

I wholeheartedly agree and would go even further and reimagine our current illumination concepts. At the moment we mostly have a few powerful point light sources. Given the longevity of LEDs we could easily design walls and furnitures with hundreds of less powerful LEDs that would produce a much more even illumination, have far less problems with head dissipation and be cheaper to produce than those high luminosity LEDs. And even more interesting, this would open the door to far more creative designs than we have now. With OLEDs you could even have glowing wallpapers: http://oled-werbedisplays.de/wp-content/uploads/2013/02/oled...

Zoomla• 13 years ago

They also currently take much more energy to manufacture then an incandescent bulb.

nickhalfasleep4• 13 years ago

What a bullshit dataless fearmongering article. If your lamp and enclosure are UL rated then the on-die temperature is well within operating parameters for the 6000 hr+ lifespan. If you go with a CREE or Philips lamp then their thermal design was built for the cooking the L-Prize and Energy Star demands of them. The DOE took their and customer experiences with CFL's to heart when designing goals for Energy Star LED lamps.

Source: I was a lighting engineer at a major Independent Testing Laboratory for 5 years before going to software full time.

nickhalfasleep4• 13 years ago

In short, get only Energy Star certified lamps http://www.energystar.gov/index.cfm?c=ssl.pr_why_es_com

To get the Energy Star rating, the manufacturer must get an independent lab to measure their operation at 45C and measure the temperature on the die (per the LED manufacturer's specs), to validate that it will maintain it's life expectancy.

http://www.energystar.gov/ia/partners/manuf_res/downloads/In...

If you want to read all the nitty gritty details.

mcguire2• 13 years ago

"the manufacturer must get an independent lab to measure their operation at 45C and measure the temperature on the die"

In an environment with no airflow?

Lagged2Death3• 13 years ago

If your lamp and enclosure are UL rated then the on-die temperature is well within operating parameters for the 6000 hr+ lifespan.

6,000 hours? Where does that come from?

The L-Prize bulb claims 30K hours; most of the LED lights I've seen for sale claim lifespans in the 25K to 50K hour range. Are you saying that 6K is all we can actually expect?

To actually get just 6K hours from a bulb that cost you US$30 or more (the L-Prize bulb is $70!) would be very disappointing.

nickhalfasleep4• 13 years ago

Since the bulbs last so long, and it would be prohibitive to wait until a death rate of 50%, they use 6000 hours as the laboratory test time which has good correlation with information known so far from LED manufacturers. By that age they tend to be in a main sequence of life.

stcredzero• 13 years ago

Aren't we hobbled by the legacy interfaces for light bulbs, in much the same way that SATA isn't necessarily the best interface for flash SSDs? LEDs are a different thing. It seems like lamps that use them should have thermal management built into them. The increase in surface area would make thermal management much easier.

magnawave• 13 years ago

Yes this is exactly the problem - less so with CFL but hugely so with LED. LEDs should appear as a part of the fixture itself - not as a screw in replacement for the legacy Edison socket. I suspect this will happen eventually when people start to see all the cool lighting options you have with LED fixtures - but its going to take a good while to get the mental shift to happen!

ubercore3• 13 years ago

I really dislike this article. It took me a little bit to figure out why. Most of the annoyance comes from fatigue of reading this kind of thing. "Humvees are more carbon neutral than a Prius" kind of thing.

Besides my personal annoyance though, this kind of unbalanced and unrigorous article is just flat out dangerous to public discourse on a pretty important issue. LED bulbs have strengths and weakness, to be sure. I didn't think the heat issue was a "secret" that "nobody will tell me". It was the first thing mentioned in nearly every single article or story I've seen about LED bulbs. I've been using LED bulbs for about 4 years now (in regular fixtures, closed fixtures, outdoor fixtures in summer and winter, closed bathroom fixtures) and have not had a single issue. As others mention, even if I did there's good warranty coverage.

I'm probably more radical than most on energy issues, but I find this kind of FUD downright irresponsible.

It also is part of this annoying trend of people that really enjoy trying to poke holes in new technology. Like electrocuting elephants with evil electric distribution technology.

maratd2• 13 years ago

I'm probably more radical than most on energy issues, but I find this kind of FUD downright irresponsible.

FUD? Seems like common sense to me.

If something comes with a heat sink, it's to disperse heat. If you're dispersing heat, you need airflow.

I know this. You know this. But the average consumer does not.

Consumers should be aware of this and this article accomplishes that.

Please keep any fanatical environmentalism to a minimum. Nobody is saying LEDs are bad. I own quite a few. It is, however, important to know how to use them effectively.

ubercore3• 13 years ago

Sure, I went off the handle a bit, but the thing that really set me off here was "what nobody will tell you." It's linkbait-y FUD. Every communication around LED bulbs I've seen has mentioned the heat issue.

ars_technician2• 13 years ago

The entire first part of your response is pointless. You are essentially admitting that you are annoyed by articles that don't agree with your preconceived notions. "it bothers me because it doesn't fit my version of black and white" is not an argument and does not belong in this discourse.

ubercore3• 13 years ago

I was just using that to lead into the thing I really wanted to say. I admit my dislike is my problem. I thought that I followed it up with reasoned and thoughtful discourse. What part of my statement do you disagree with?

hyperpape• 13 years ago

In mild support of your comment: I haven't bought any LEDs yet. I found out that they had reached practicality when I saw a display in Home Depot a few months ago (last I'd heard was years ago, that they were too expensive). Yet I still managed to hear that you can't use them in enclosures. I can't even remember where: it might have been some guys talking at the office.

I'm sure that there are people out there who don't know this, but it also seems like it's approaching common knowledge.

neltnerb3• 13 years ago

So, I actually own an LED lighting company, and I found the article quite fair. This has been bugging me for a while with the new LED bulbs, there's frankly no reason to get them to replace a CFL except for mercury, and the build quality is garbage. The heat sinking stuff is absolutely critical, and while yours may be fine, a lot of these bulbs (and more every year that new players get into making them) are simply not amenable to being used as direct replacements without some extremely clever design that's not being done.

Not to mention that the incremental efficiency gain is negligible. Incandescent to CFL is a huge efficiency gain, so you can actually pay back the increased cost in electricity usage in a short while. A 60W equivalent CFL might consume ~13W. A similar LED bulb will be around ~9W. That extra 4W is such a marginal improvement that it would take decades to make it back in energy cost. So the only selling point is lifetime, and I've seen no indication that there is a big difference between the two -- both have similar types of failures, usually control electronics or power supply passives due to poor quality manufacturing.

jotm2• 13 years ago

I love my 35 watt CFLs, and still can't find any LED equivalents at an affordable price :-)

maratd2• 13 years ago

there's frankly no reason to get them to replace a CFL except for mercury

Isn't that enough? I try to keep things that can kill me to a minimum.

weaksauce• 13 years ago

Fwiw... The elephant thing was a planned execution of an aggressive elephant. The video being shown as far and wide as possible(and likely the reason he got involved in the first place) was a business decision by Edison because he had a lot of money invested in DC distribution.

http://en.wikipedia.org/wiki/Topsy_(elephant)

Spooky232• 13 years ago

The whole lightbulb debacle is a great reason why the government regulatory regime needs to stop meddling with the marketplace.

Until 2000, buying a lightbulb was an unconscious act. You go to any store, and buy a fucking lightbulb. 80% of sales were 60w. Some applications call for different bulbs.

Now, solutions for getting light out of edison sockets take up A FULL AISLE in Home Depot, with a dizzying array of choices that are difficult to evaluate.

You can buy normal lightbulbs, except that now most of them are mislabeled -- a 60W bulb may actually be 50W. 100W bulbs are impossible to find and cost $5/ea.

You can buy CFLs. Some are great, others make your living room look like a gas station bathroom in 1960. Most suck, and as a layman, I now have to know what color temperature is. And, oh yeah, many bulbs, which cost 5x-10x the original bulbs, burn out quickly in fixtures, or burn out quickly when in any orientation other than a standard lamp. (ie. put them in sideways, or mount them upside down)

Now you have LEDs, which sometimes have better light quality, but they cost $20. And while they may last longer, you need to be an engineer to evaluate the appropriate bulb for the appropriate application.

Just let me buy a bulb and pay more for electricity.

jonknee• 13 years ago

Now, solutions for getting light out of edison sockets take up A FULL AISLE in Home Depot, with a dizzying array of choices that are difficult to evaluate.

So that damn government meddling has resulted in too much choice in the free market?

Spooky232• 13 years ago

No, it's resulted in a bunch of subpar choices by largely eliminating the best choice from a qualitative perspective.

The government decided that modifying the electricity demand curve was more important than me having light that meets my needs when the sun goes down.

A free market approach would allow me to make decisions based on cost and other factors. For example, my basement and garage are lit by efficient CFL and very expensive LED lighting that was installed when the house was purchased several years ago.

In my office, I find a standard incandescent bulb better than the more efficient alternatives. I value not getting a headache every evening more highly than the $8 I spend in electricity annually on those bulbs. So now I have to resort to hoarding light-bulbs.

I'm an engineer passionate about efficiency, so I tweak stuff like this. My mom isn't -- she ends up suffering with awful light.

rsync• 13 years ago

One disagreement:

"You can buy CFLs. Some are great, others make your living room look like a gas station bathroom in 1960."

Please, please don't. We all have a duty, with our wallets, to make CFL die. It is garbage, stopgap technology that should have been strangled in the crib. Oh and also it's toxic waste.

Buy LEDs. Buy incandescents. Buy xmas tree lights. Buy anything but CFLs.

mistercow• 13 years ago

It seems like the obvious solution to this is to actively increase airflow. Small fans or synthetic jets could be included on the bulbs themselves, although this would be tricky to do compactly, especially for fans.

Alternatively, they could be built into light fixtures designed specifically for LED bulbs, which would be less expensive overall, and would allow the cooling to be designed for the specific fixture (face up vs. face down, for example).

That 60W-equivalent LED: What no one will tell you

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