# Inside a cheap LED bulb



## Black Dog (Oct 16, 2011)

GrayHair said:


> Members seem to be in agreement that most LED bulbs from the far East are junk. If you haven't been inside one, here is a video blog with examination and evaluation (starts at 39:10). The blogger is Australian electronics engineer Dave Jones :thumbup: who pronounces LED as one word with short _e_). When he breaks out the FLIR camera, remember he uses C. This might be a good watch for even non-technical people. Show them what they will get from a big box store.
> 
> *EEVblog #735*
> https://www.youtube.com/watch?v=V9tcC7Ks4_c
> Regards!


:thumbsup:

Don't look that LED will last 50 years:laughing::no:


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## randolph333 (Feb 10, 2015)

On the other hand, here's some discussions of the Philips SlimStyle, which does it right:
http://www.allledlighting.com/author.asp?section_id=455&doc_id=562607
http://www.designingwithleds.com/sneak-peek-philips-slimstyle-led-60w-replacement-bulb-review/
http://www.designingwithleds.com/closer-look-philips-slimstyle-led-light-bulb-driver/​


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## Electric_Light (Apr 6, 2010)

Philips Slim Style uses failure prevention sensor that is used to dim so them LEDs don't become non-light emitting friodes.


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## Electric_Light (Apr 6, 2010)

I didn't mean it as a feature. It's like a limp mode on a car. It throttles down by lowering the lumen output and maintains throttled unless there's adequate cooling. 

So, when used in an enclosed fixture, an LED claiming 800 lumen may only be putting 400 lumen after 15-20 minutes of use while a 60W incandescent lamp will put out 800 lumen throughout the whole time.

Specification requirement becomes important, so you can declare that LEDs that fades down after a warmup can is non-conformance and make the energy retrofit sales company redo absolutely everything.


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## wendon (Sep 27, 2010)

Electric_Light said:


> I didn't mean it as a feature. It's like a limp mode on a car. It throttles down by lowering the lumen output and maintains throttled unless there's adequate cooling.
> 
> So, when used in an enclosed fixture, an LED claiming 800 lumen may only be putting 400 lumen after 15-20 minutes of use while a 60W incandescent lamp will put out 800 lumen throughout the whole time.
> 
> Specification requirement becomes important, so you can declare that LEDs that fades down after a warmup can is non-conformance and make the energy retrofit sales company redo absolutely everything.


Wouldn't you be able to tell the difference?? I've never seen that phenomena.


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## Electric_Light (Apr 6, 2010)

wendon said:


> Wouldn't you be able to tell the difference?? I've never seen that phenomena.


Not always easy to tell, but not immediately noticeable does not mean that it's acceptable. You'll find that wearing 50% tint sunglasses don't "feel" 50% dark, because our eyes adjust the pupils to accommodate. 

The best way to tell is with a power meter using a sufficient quantity of LOLed bulbs. If you have ten 10W loLED bulbs that starts at 105W total, but decline to 70W after 15 minutes installed in real life fixtures that you intended to use them in, the failure prevention control circuits are dimming them down. This kind of failure prevention is useful in computers or cars to avoid system destruction in the *event of a malfunction*. This means that the computer slows down if the heat sink is clogged up dirt so it doesn't crash the system or damage components, but if it happens on a regular basis and the computer starts at 1,000MHz and stays there for the first 5 minutes, but indefinitely runs at 700 MHz, for all intents and purposes, you have a 700 MHz computer. 

To the average eyes, slow fading over 15 minutes by 30% isn't noticeable unless you're specifically told to watch for it. An LED lamp without a failure prevention sensor continues to operate at the rated output while temperature continues to rise and cause a premature burn out if the cooling/ventilation is inadequate. 

A self destruction avoidance enabled LED can cause an unethical cover-up for LEDs that don't conform to specs. If it was pitched as 800 lm, put into a fixture and it is constantly leaning onto the failure prevention system and sagging down to 600 lumen, the vendor needs to be nabbed. That's unless the project specifications allow 25% reduction in output after 15 minutes of continuous use. 

One of the reasons you should NEVER allow LED vendor reps to take charge of commissioning performance verification.

"What difference does it make?" 
LEDs are rather commonly used in Public Works. So, a competitor's proposal, and they had to use something that constantly falls back on self-destruction prevention circuits to keep prices competitive, it's a very legitimate reason for a bid protest.


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