Electronics > Projects, Designs, and Technical Stuff
New LED lights reliability
001:
is it sort of holywar? :popcorn:
Kjelt:
--- Quote from: timelessbeing on February 09, 2019, 10:11:12 pm ---All bulbs I buy at my local home improvement store should be able to withstand being switched on and off, many times per day. I think that is a reasonable expectation.
--- End quote ---
Yup up to 10000 times or more if the manufacturer says so on the package because you know what on switching rectified mains pulse does with the bus capacitor.
Was it better with conventional bulbs? No they lasted 1000 hours and a lot less if you switched it on at peak if the AC wave. I had some conventional bulbs blow in a few months, bad luck few times switch on at peak.
There are softstart designed for this purpose.
Zero999:
Photonicinduction did a good video on this. The corn cob style LEDs seem to be the worst.
https://youtu.be/ikAql0nbSfs
djacobow:
--- Quote from: Kjelt on February 09, 2019, 11:24:12 am ---But as said earlier hard to explain to grandma Jones, hell it is obvious from this topic that even EEs sometimes have no clue and start brabbling all kinds of nonsense from their statistical experiment with n=1. :palm:
--- End quote ---
Oh, FFS no. If you have to explain how a particular lightbulb works to Grandma Jones, then you have failed. Your lightbulb has failed. Your product is a failure and it deserved to fail. It's as simple as that.
Lightbulbs are not esoteric engineering products intended for use by experts. It's lighting, as in the first or second household application of electricity. People have expectations for how a lightbub will perform and nobody who doesn't have a particular interest in lightbulbs should have to build up a working knowledge of the constraints and limitations of a particular trechnology or implementation in order to make decisions about it, especially if the product is being marketing as retrofit.
I don't see the relevance of the rest of your post. Do incandescents fail if they are switched too much? Sure. But people know that. And the incandescent manufacturers aren't making any new claims. Their basic claim is the same as ever: this lightbulb works like that last one and costs $0.80. Will any old bulb work in an attic that where it is used for 30 minutes a year? Sure. In fact, there is absolutely no reason to put an LED there since the total lifetime energy use is negligible.
You make an interesting but ill-conceived point about n=1, that people should not form judgments from their very limited experience. Though this is true, I've got some news for you: that's indeed how they do it. They're not going to consult government reports on lightbulb performance. They are not going to sift through Consumer Reports lightbulb reviews. They are not going to build up a spreadsheet collecting data from their friends and neighbors. They are going to buy one bulb off an endcap at the local hardware store for $8 under the promise that it will save them some money in the long run, and they will screw it into the next available socket. And if that bulb fails in a year or two, they're going to remember that outcome, and that will be the end of $8 bulbs for that person for a decade or more. (or until they have no choice)
That is how people make these kinds of decisions. Economists call this "bounded rationality" and contrary to being a sign of stupidity or laziness, it is a reasonable way to make decisions in a complex world where you don't have the time or resources to know about everything. Given this behavior, LED manufacturers would be smart to design product that are extremely unlikely to fail in the promised time. This means, for example, that if you want to make a claim of 20 years life, you might want a product with an MTBF several times that. It also means not shoving the restrictions and limitations of the bulb into a blob of fine print on the side of the box where it serves primarily to protect the company rather than inform the consumer.
Finally, in my case, I have had 7 LED failures in 6 sockets in just over 7 years. It's more than large enough N to know that there is something amiss between the label on the package and reality.
PS -- I don't like that I have to play the "anti LED" guy in a thread like this. I actually like LEDs and want them to work. There is a reason I keep buying them. They have qualities that I rather enjoy and in fact, I prefer the light output of them over incandescent. There is not a single incandescent bulb in my house today and only a few fluorescent remain in fixtures that have build in ballasts and are in locations that are difficult to access for replacement. But I have also been burned by LED retrofit bulbs repeatedly, and man, I can not I not stand fanboy bullshit from people who will tell me to my face that my direct experience is irrelevant or that worse, that I would not have this experience if I wasn't so damned stupid.
texaspyro:
My house has over 300 bulbs... most are recessed ceiling can type lights or spotlight type bulbs painting walls / artwork. Around 10 years ago I looked into doing a LED upgrade... it would have cost $14,000 dollars. Then I found an Ebay seller offering what were large (20-50 piece) lots of apparently big-box store returns for dirt-cheap prices. Almost all were made for Sylvania and others by Lighting Science Group. It turned out the price of those cheap LED bulbs was very close or lower than to the price of halogens at the time. I wound up paying around $1000 plus another $400 dollars for some specialty high CRI bulbs for the kitchen, my office, and some artwork spotlights.
Anyway, I replaced all the incandescents with LEDs. I had been replacing at least one incandescent a week and if one of the PAR20 halogens in the kitchen died it often took out a few other bulbs and a $30 dimmer. I kept a closet filled with spare incandescent bulbs. Over the last 10 years I have have replaced a grand total of 3 (count 'em... three) LED bulbs and 0 dimmers.
My LED bulbs are old-school models with massive, very heavy heat sinks. Their light output is around 70 lumens per watt. Their light output exceeded the incandescent / halogen bulbs that they replaced. I have had one running 24/7/365 for 10 years. I have a sophisticated integrating sphere setup that can measure light output and color temperature. Periodically I check that bulb for light output... it is still virtually the same as when I first installed it... LEDs seem to be quite a bit more stable over time than originally predicted.
The problem with newer LED bulbs is that they have been cost reduced to the maximum using flimsy heat sinks and lower cost components.
An interesing thing happened with the Sylvania PAR20 LED bulbs... they were recalled. I shipped over 100 back and got brand new replacements for my used bulbs.
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