Engineering News Blog

Engineering News

Latest news of interest to engineers. Sourced from GlobalSpec's Engineering News
Previous in Blog: Anonymous Donors Fund Solar Projects Across the U.S.   Next in Blog: MacBook Pro Declared 'Best Performing' Windows Laptop
Close

Comments Format:






Change Mode
Close

Subscribe to Discussion:

CR4 allows you to "subscribe" to a discussion
so that you can be notified of new comments to
the discussion via email.

Close

Rating Vote:







Add Vote
9 comments
Rate Comments: Nested

We've Finally Figured Out What Makes LED Bulbs So Inefficient

Posted April 24, 2013 1:00 PM

From Popular Science - New Technology, Science News, The Future Now:

LEDs should be lighting the way to a greener future: They use 75 percent less energy and last 25 times longer than incandescent light bulbs, and they do so at a cooler temperature. But right now, we mostly use LEDs in electronics, because they have a bit of a drooping problem: at higher currents, the amount of light they produce takes a nose-dive. The efficiency droop has baffled scientists for years, but researchers at the University of California, Santa Barbara and France's École Polytechnique say they've finally solved the mystery.

Reply

Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

"Almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!
SolarEagle
Guru

Join Date: Mar 2007
Location: by the beach in Florida
Posts: 33392
Good Answers: 1817
#1

Re: We've Finally Figured Out What Makes LED Bulbs So Inefficient

04/24/2013 2:42 PM

Artistic interpretation of auger recombination....

__________________
 All living things seek to control their own destiny....this is the purpose of life
Reply
PWSlack
Guru
United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
Posts: 32175
Good Answers: 839
#3
In reply to #1

Re: We've Finally Figured Out What Makes LED Bulbs So Inefficient

04/24/2013 6:40 PM

Please don't do that.

__________________
 "Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
Reply Score 1 for Good Answer
No more "Almost" Good Answers.
tcmtech
Guru

Join Date: Jun 2009
Location: South of Minot North Dakota
Posts: 8376
Good Answers: 775
#5
In reply to #1

Re: We've Finally Figured Out What Makes LED Bulbs So Inefficient

04/25/2013 12:24 PM

Some days my wife gives me headaches that create a similar effect.

Reply
Yahlasit
Guru

Join Date: Dec 2008
Location: Cd. Juarez, Chihuahua, Mexico.
Posts: 1023
Good Answers: 69
#2

Re: We've Finally Figured Out What Makes LED Bulbs So Inefficient

04/24/2013 5:29 PM

How about just more of them in parallel ?, that way you could increase the total current while keeping the current thru each branch below the point where the efficiency drops.

__________________
 No hay conocimiento ni herramienta que sustituya al sentido comun.
Reply
redfred
Guru
Engineering Fields - Electrical Engineering - Been there, done that. Engineering Fields - Control Engineering - New Member

Join Date: Dec 2008
Location: Long Island NY
Posts: 15603
Good Answers: 982
#4
In reply to #2

Re: We've Finally Figured Out What Makes LED Bulbs So Inefficient

04/25/2013 9:13 AM

Trouble is driving any array of non-linear devices (LED) in series or parallel will always make for uneven power loading to each device as the devices age. So as one LED grows brighter by a factor less than two for a doubling of current through that LED, the sum of the remaining LED array will dim more than the one that brightens.

I do believe that this is a problem that can be solved one day for LED lighting arrays. I suspect the solution will happen at the design of the LED device itself.

__________________
 "Don't disturb my circles." translation of Archimedes last words
Reply
Spinco
Guru

Join Date: Sep 2008
Posts: 706
Good Answers: 32
#6
In reply to #4

Re: We've Finally Figured Out What Makes LED Bulbs So Inefficient

04/25/2013 12:40 PM

I just had a weird experience with LED bulbs. I bought 2 LEDs to install on the two wall sconces on either side of the bed. I also installed a remote control dimmable switch to operate the 2 sconces since the wall switch is on my wife's side of the bed and she often nods off before I do. The operation had worked fine with 2 incandescent bulbs. When I installed the LEDs it seemed to work OK until I went to shut it off. Then they would dim down but after I hit the shut off they continued to dimly glow. I waited thinking that maybe a capacitor had to discharge completely but no, they continued to glow. I unscrewed one LED and replaced it with an incandescent and tried it again. This time both went out, LED and incandescent. Other than the fact that the incandescent probably has a higher resistance due to the filament and I'm not up on the workings of an LED it did baffle me. Any ideas? Ö (supposed to represent a light bulb)

__________________
 Spinco
Reply
redfred
Guru
Engineering Fields - Electrical Engineering - Been there, done that. Engineering Fields - Control Engineering - New Member

Join Date: Dec 2008
Location: Long Island NY
Posts: 15603
Good Answers: 982
#7
In reply to #6

Re: We've Finally Figured Out What Makes LED Bulbs So Inefficient

04/25/2013 12:46 PM

My WAG is your SCR dimmer needs a lower impedance to drive to be fully turned OFF.

__________________
 "Don't disturb my circles." translation of Archimedes last words
Reply
SolarEagle
Guru

Join Date: Mar 2007
Location: by the beach in Florida
Posts: 33392
Good Answers: 1817
#8
In reply to #7

Re: We've Finally Figured Out What Makes LED Bulbs So Inefficient

04/25/2013 12:57 PM

but what's the fix ? They do make these control switches for LED's....

http://www.creativelightings.com/LED-Controllers-LED-RF-Remote-Controllers-s/959.htm

__________________
 All living things seek to control their own destiny....this is the purpose of life
Reply
redfred
Guru
Engineering Fields - Electrical Engineering - Been there, done that. Engineering Fields - Control Engineering - New Member

Join Date: Dec 2008
Location: Long Island NY
Posts: 15603
Good Answers: 982
#9
In reply to #8

Re: We've Finally Figured Out What Makes LED Bulbs So Inefficient

04/25/2013 1:55 PM

Yes. A dimmer that can handle an LED bulb and that will completely turn OFF does exist. It seems that it does not exist in this bedroom.

__________________
 "Don't disturb my circles." translation of Archimedes last words
Reply
Reply to Blog Entry
Have a Different Question?
9 comments

"Almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!
Copy to Clipboard

Users who posted comments:

PWSlack (1); redfred (3); SolarEagle (2); Spinco (1); tcmtech (1); Yahlasit (1)

Previous in Blog: Anonymous Donors Fund Solar Projects Across the U.S.   Next in Blog: MacBook Pro Declared 'Best Performing' Windows Laptop

Advertisement

Got Something to Say?
Ask a Question
Start a Discussion

Search this Section
General Discussion:
Go

Search this Blog
Engineering News:
Go

Recent Blog Entries

CR4 Sections
Aerospace
BioMech & BioMed
Chemical & Material Science
Civil Engineering
Communications & Electronics
Education and Engineering Careers
Electrical Engineering
General Discussion
Instrumentation
Manufacturing
Mechanical Engineering
New Technologies & Research
Software & Programming
Sustainable Engineering
Transportation

Site Directories
Forum Directory
Blog Directory
User Group Directory
RSS Feeds

CR4 Rules of Conduct
CR4 FAQ
Site Glossary

Who's Online (70 right now)
Show Members
Advertisement