How long do LED shop/ceiling lights really last at full output anyway?

See Appendix C as I stated in my other post. Then tell me how your methods are so superior to those used by the experts.

Do you honestly think that proves anything?

I have 3 CFLs in a lamp post since 2000. Just this year, one of them gave up the ghost. They are activated when it gets dark. So, they're on at least 12 hours a day, every day. Construct some statistics out of that.

--
Dan Espen
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Dan Espen
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I can assure you, we replaced incandescent floodlights back in 2010 with LEDs in one of our buildings. These lights are on 8 to 10 hours a day, if not longer and we've yet to replace any of them (over 50).

I understand your skepticism as a general consumer, but I've been experiencing the products first hand. I've been dealing with LEDs for many years and I agree, they do diminish in brightness after their manufactured rating, the quality lamps last up to their claim if not longer. Of course, we don't purchase the cheap ones you buy at Home Depot.

Reply to
Meanie

Dan, You come across as challenging the facts, but, you provide few facts on your own. It's easy to challenge, but it takes effort to back up your challenge.

I read my electricity bill. Those are "my" facts.

I don't even have to show you my bill. I'll simply point you to the PG&E Tiered Plan that I'm on:

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Do you see *anything* anywhere near 10 cents? Anything?

Look again:

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The first tier (which lasts about a week) is almost double that. The next tier is almost triple. And the fourth tier, the one that you use for the second half of the month, or the last week, if you're frugal, is almost quadruple that.

Those are facts. Do you dispute the facts?

What facts do you have for my rate that dispute that?

Reply to
Algeria Horan

I understand your point, which is that I can say it lasted 10,000 years. If I could prove it completely, and if it was worth the effort, I would, just like Jeff *proved* that WiFi reception in routers was NOT what the manufacturers claimed.

But you are like those people who say "prove it" to everything, which is fine, but *you* have to provide some semblance of a reason to go to the effort to prove things that we just have to accept on faith.

I was backing up your unproven claim that Jeff was not being balanced, in effect, when I know, from the last decade on s.e.r and a.i.w that Jeff "is" well balanced, and he proves what is worth proving.

You entirely and completely missed the point. Did you buy too many arguments this week?

All I was saying is that your claim against Jeff's veracity are completely unfounded. You're entitled to your opinion, but if I asked you to prove that you had sex with your wife five times this week, do I really expect you to prove that?

What I'm saying is simply that your criticism of Jeff was unfounded, if you look at the entire record. And, I'm saying that 11 cents per kilowatt hour is a magical number entirely unachievable by me, in California.

If you claim otherwise, I'm only asking you to attempt to back up your very own claims with fact, as I did with Jeff, and as I did with the price of electricity in California.

Reply to
Algeria Horan

That is the reason they last so long. What people don't realize is the life of fluorescent, whether tubes or CFL, is shortened when they are subject to constant on and off. They are not made for constant on/off action unless the fixture contains a "program start" ballast. Due to the cost of that ballast, they will not be within the common hardware store fixture. When fluorescent lamps remain on all day, chances are you can see 10 years on them. The average home will not see that life cycle since it's not common to leave them on all day everyday.

Reply to
Meanie

I don't run statistics, but I appreciate what you wrote because my fluorescent lamps don't last more than a year or two, it seems.

I used to mark the bulbs with a Sharpie, but I stopped doing that long ago. I don't think I *ever* got anywhere near the claimed life.

But we turn them on and off a few times each day.

Reply to
Algeria Horan

This is good to know because the whole point of this thread is to nail down the actual life of the lamps.

Of course, you can't expect me to NOT buy at Lowes or Ace or Home Depot, for quantities such as we buy for a home as replacements, so the word 'quality lamps' is to be taken with a grain of salt.

But at least it's good to know that you *understand* that an LED is never as bright as it was on its first day, and that cycles, and heat, and vibration exacerbate the existing cracks between crystals, such that LEDs drop off exponentially in light output over time.

As stated in the standards that Jeff kindly referenced early on in this thread, the diminished light output is very difficult to detect, since it happens over time, and since there may be other bulbs compensating for the lack of output, such that an LED bulb that has actually reached it's L70 lifetime may not be easily observed by you.

Nonetheless, if the driver failed, which I think can be the weakest point (that premise needs to be explored), you'd know that. But you might not know when any particular bulb has reached its L70 point without isolating the bulb and actually measuring the output (since the gradual decline in output isn't going to be suddenly noticeable, according to that report Jeff referenced).

My point is that things failed, perhaps, and you don't realize it. But that needs to be explored since you'd know of some failures (but not all, unless the bulbs are isolated, and if you have a keen eye for such things).

Reply to
Algeria Horan

I should have guessed it was you. I like to explain how things work, without offering a judgment or opinion. This type of question really belongs in Candlepower Forums.

It happens. I have some marketeering experience somewhere on my resume. Speaking of bullshit: "How LED Lighting May Compromise Your Health"

Nice summary. Sounds about right. I believe there are a few other standards that I missed. Standards are a good thing. Every company should have one.

Nope, because it's all we have to work with. Like I ranted, nobody does 30,000 hr life tests. Therefore, nobody knows the "real world" lifetime of an LED light. The best we can do is parametric testing, accelerated life tests, and the usual guesswork. The first two are quite valid and result in numbers that usually come fairly close to reality. The guesswork, you can guess what I think.

It's much like MTBF (mean time between failure) which attempts to estimate the life of a device based on historical tests and operating conditions. These component estimates are conglomerated into a figure for the device. However, the intent is not to estimate the lifetime, but rather the number of expected failures in a population of LED's. "What Every LED Engineer Needs to Know About MTBF" (Note: I haven't read through this yet)

600lumens / 9watts = 67 lumens/watt. Barf. Philips claims 200 lumens/watt and Cree claims 300 lumens/watt: You may not see that at Costco for a while, but maybe if Philips and others get back into the LED biz. It's not too obvious, but both claims assume that the LED is cooled to approximately room temperature.

For good reason. From the point of view of the manufacturer and vendor, the ideal product blows up 1 day after the warranty expires. I've ranted on the topic before, where simulation and modeling tools are used to insure that multiple parts all fail just after some preset time limit. My favorite example are GE(?) water heaters with 6, 9, and 12 year warrantees, and roughly proportional pricing, but where the only difference is the type and size of the anode rod. Details if anyone wants them.

Talk to me in 30,000 hrs and we'll compare notes.

You have a talking clock?

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Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Reply to
Jeff Liebermann

Which is impossible to do based on unreliable anecdotal evidence in an usenet newsgroup read by perhaps a hundred people.

Reply to
Scott Lurndal

One more. ARL: "Average Rated Life (ARL) is how long it takes for half the light bulbs in a test batch to fail" I seem to recall others, but I'm too lazy to Google.

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Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Reply to
Jeff Liebermann

How does the cost of a Kwh contribute to the rated lifetime of an LED-based illumination device? I smell a red-herring. Costs of electricity vary widely nationwide. Yes, California has more expensive electricity (specifically to encourage conservation) than other parts of the country, but that is not a factor in rated lifetime.

Tj and cycles (on/off) would seem to be the two major controlling factors, just as they are for incandescents.

Tj = Junction Temperature.

Reply to
Scott Lurndal

Well, you're entitled to invent a new testing standard, along with yet another collection of artificial test conditions, that will satisfy your vision of a "real world" test. I've only had three LED light failures. All were in the bathroom, all were failures of the driver electronics, two were mounted inverted (base up), and all were retrofitted into incandescent fixtures with miserable ventilation. Therefore, I propose a bathroom LED test, which includes heat, condensing and non-condensing humidity, on-off cycle time, over voltage, erratic power glitches by PG&E, limited ventilation, and dust accumulation. Such a test will clearly define what might be expected from "typical" bathroom LED service. The EU micro managers have specs and tests for almost everything and will surely appreciate your efforts on their behalf.

I think you need a major dose of testing reality. Instead of LED's, let's try drug testing. In order to release a new drug, one of the tests that a pharmaceutical company must survive is a cancer test. This is usually done with mice or rats. However, they're not ordinary mice or rats. If such a cancer test were performed on the common and ordinary breeds of mice and rats, the number of tumors found would be very small and therefore statistically useless. In order to get statistically significant numbers, mice and rats that are genetically predisposed to developing cancerous tumors are used.

For LED testing, much the same trick is used. If you don't have a sufficient number of failures during the test period, and you can't extend the test period, you do whatever it takes to produce those failures. The easiest is to elevate the temperature. For incandescent lamps, raising the filament voltage also works. By plotting a trend line of different temperatures or voltages, one can extrapolate the graph to obtain a fairly good approximation of the expected lifetime at more sane temperatures and voltages. That's how one avoids multi-year tests.

There are quite a few products that suffer from inflated specifications. Battery capacity (in particular 18650 cells), flashlight output in lumens, wi-fi range/speed, laptop battery life, laser printer toner cartridge pages, inkjet cartridge pages, etc. All of these are characterized by inflated claims contrived to make the numbers bigger. I can explain any of these in detail if you want to know how it works. The reasons are competitive pressure and product differentiation. Every manufacturer and vendor are trying to sell on the basis of everything except price. So, they push service, warranties, packaging, bonus junk, etc. Eventually, they run out of these fringes, and start inflating the specifications on the assumption that the typical customer doesn't understand the specs. I think this thread demonstrates that this is true. Instead of inflated, perhaps "grossly exaggerated" might be more accurate.

Sniff...

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Jeff Liebermann

I remember reading in your prior reference that the time for half to fail isn't useful for LEDs though, since they fail differently.

Reply to
Algeria Horan

Yeah, it's me. My friends joke I'm half the Internet alone.

I'm always solving problems, asking questions, delving deeper, etc., as are you (but you don't like to admit it).

You have always been balanced, ever since I learned from you how to set up my WiFi rooftop antenna on a.i.w years ago, when you still frequented that forum (before you absconded to s.e.r that is).

Me too, truth be told (but I try to hide my curricum vitae far more so than you do).

When I was in Marketing, we made hay with any advantage we could, and we swept under the rug all the disadvantages. Plus we said things like "better" and "new" and "more" since they couldn't be easily disputed.

Basically, we took whatever it was that the engineers gave us, and we marketed the shit out of it, so that it *looked* like gold in the literature.

But it was no different than anything else was. Every good thing had a bad downside to it.

Like everything on this planet does.

OMG. I'm losing out on all that healthy infrared radiation! And that EMF is the "leading cause of blindness" in the USA! Quick. Gimme one of those famous infrared saunas in Santa Cruz hippytown!

:)

Thanks for noticing. I generally read all your references. If you are gonna go to the trouble to reference them in a thread I authored, I'm gonna go to the trouble to at least skim them (I read fast, very very very fast, faster than most people can talk, and I type fast too, so it's easy for me. When I was a kid, I was in a special reading program for the gifted, where they had a machine that forced me to read faster and faster and faster - dunno why my parents subjected me to that - but they did.)

I think the important point is that we each can pick the standard that makes the most sense to us, but also, that information has to be readily available to us.

I'm not sure yet, which is the readily available standard, but I'd prefer the L70 myself, to be the standard that I get the information on.

At the moment, I'm guessing the one LED lamp I have will last no more than 4 or 5 years. (Call me up in 5 years and I'll let you know how it turned out.)

Except that every once in a while, there will be failures in the drivers that I don't think are being tested here. Are they?

Understood.

Makes sense.

The abstract mentions MTTF, which is essentially what I'm asking in this thread, I believe, whereas MTBF is for repaired items (according to the abstract).

It implies that we should use MTTF since we're gonna throw out the LED fixture once it fails us.

That Fairchild paper goes into details (e.g., how to accelerate and what happens if the failure rate is 0), but that's the net I take out of it by a quick skim.

The funny thing is that there are so many stupids out there who talk about "warranties" as if they're NOT purely marketing bullshit!

On the car forums, I hear all the time people comparing batteries by their warrantee, as if the warrantee conferred some magical quality on the electrical and lifetime properties of the battery!

They even compare *tires* by warrantee! Geesuz. It's sad how stupid people are, in general. Very very sad. Sigh.

Interesting. Very interesting. I just had a water heater go, in fact, and, um, I shouldn't say this, but I had never replaced the anode. All that was left was some whitish stuff and the inner steel wire. The heater corroded in

7 years, but that was my fault for not replacing the anode (although it was almost impossible to twist off, so, if you're gonna replace anodes, at least crack the top hexnut every six months or so).
Reply to
Algeria Horan

Fair enough point.

Reply to
Algeria Horan

Good point. I don't even remember how we got into the costs, other than I made a joke that I'd love to live in Louisiana where the costs actually were listed as around that amount.

Agreed. We're talking actual lifetime of the LED "unit" (which includes whatever can be replaced, which, for a household unit, is usually the driver and chips and the housing, all in one package like my Costco setup).

Interestingly, the paper Jeff originally cited mentioned three main factors, all of which exacerbated existing physical cracks between crystals:

  1. Cycles
  2. Heat
  3. Vibration

To that, Jeff noted his bathroom fixture had a few more, mainly: a. Humidity/moisture b. Dust & orientation (aka heat retention or dissipation) c. Voltage variations (e.g., we have *many* power outages per year here)

I'm only about 30 miles from Jeff (give or take) but we lose our power so often that I don't know of many people who don't have a built-in generator out here (plus we need the power to pump the water to fill our sinks).

So, overvoltage is key here. Very key. (I have holes blown in some of my appliances, for example - even though I can't prove what caused it - certainly I can see the burn marks and the high failure rate of fixed appliances.)

Reply to
Algeria Horan

Fair enough response.

I believe that. I suspect, but without personal experience, that the LED drivers are the weak link in the LED setup. I haven't looked at one yet, but a single electrolytic cap would tell me as much. I know you know electronics well, so you'd know more of what to look for, but, I know wet caps dry out (among other things that go poof over time).

Yup. You had 'em all, especially:

- Heat

- Cycles

- Humidity (which wasn't mentioned in the previous articles)

- Overvoltage (which also wasn't mentioned, but happens all the time) etc.

Fair enough assessment.

I have one degree in the life sciences, so, I'm familiar with details.

I have another degree in engineering, so, again, I'm familiar with details (remember, I invited you to the inventors club, long ago?).

Ummm... er.... almost *all* products suffer from inflated specs. You know this from looking at anything built by Apple, for example.

Yup. I was in marketing myself. The stupids outnumber the intelligent parsers 10,000 to one.

There are still people who believe Techron (aka polyetheramines) are something special to Chevron, for example, or that high-octane fuel is somehow (magically?) better than regular octane fuel.

Or, that a battery with a longer warrantee is somehow, electrically, better than a battery with a shorter warrantee.

Back to LED lifetime claims, I'm shooting for 4 or 5 years. If my one LED fixture meets that expectation, I'll be happy as the Philips wacko sized fluorescents lasted 1/4 that each time, until I got sick of replacing them.

Reply to
Algeria Horan

You've still failed to challenge any of the methodology listed in Appendix C.

I'm not challenging any facts. I know damn well I don't have any. All I have is my own experience. Those would be anecdotes, not data.

But unlike yourself, I don't go around saying the experts are wrong. I look at the source, the methodology, think about any motivation the source may have to falsify and judge who to believe.

If that chart shows an average price for California that doesn't square up with your experience, then maybe other consumers in California pay less. What you see on your bill is irrelevant to the average price of electricity in California.

So, you started out with the completely specious claim that LED lifetime was for the LED component and not the driving electronics. That is still ridiculous.

LEDs work and work well. Most people can buy them and never have to change the bulb again. You running around making blind assertions isn't going to change any of that.

So, how long to shop/ceiling lights _really_ last? Why not read the package and believe what it says? If you want to challenge the published numbers, it stands to reason, you have to use better methodology than that shown in Appendix C. Good luck with that.

--
Dan Espen
Reply to
Dan Espen

OK, looked up my records. My first prototype was a 10 LED array with my own power supply (LED switching current regulator chip) running 300 mA. This has been in heavy use in our utility room since april 2013. Absolutely no sign of dimming. I'd guess that's gotten over 6000 hours of use.

Then, I built a 20-LED string to retrofit a dual fluorescent tube fixture in our kitchen, and put that in in January 2014. A second string went in in April 2014. These are powered from a commercial LED lighting power supply at 350 mA. I'd guess the older one of these may have accumulated up to 8000 Hours of operation. It is possible these have dimmed SLIGHTLY, I have one standard dual-tube fluorescent left that I haven't gotten around to retrofitting yet to compare to. But, the pattern of light output is different enough that any comparison is pretty subjective.

Anyway, I'm sure happy with the results. I cut power consumption from 103 W down to 21 W, with perhaps a SLIGHT reduction in light output. Those 48" T12 tubes are getting pricy, and it seems by reducing mercury content, the lifetime has been reduced, too.

Now, these are NOT commerical off-the-shelf LED lighting products. See

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for some description and a picture. (That picture, by the way, is by camera flash, the LEDs are OFF, or the picture would have been BADLY overexposed, the LEDs are insanely bright if you look at them without the diffuser.) The trick is the several square inches of PC board copper per LED acts as a heat sink and keeps the LEDs from overheating. If a commercial fixture or bulb doesn't address this, then the lamps will have a short life.

Jon

Reply to
Jon Elson

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