Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

LED life

LED life

LED life

Can anybody suggest a good LED reference?  I am specifically concerned about degradation of the LED over time.  What would a curve of luminous vs time look like?  I expect to run the LED's at about 12-15mA.


RE: LED life

That will be brand and style dependant.  Consult the datasheets for the vendor of the LEDs that you are interested in.  I tend to use Stanley at lot, and that info is buried, but is still there.  You just have to look real hard.  Other vendors may be the same way.

I know that blue LEDs don't last anywhere near as long as red LEDs.  High brightness LEDs run at about 1/3 maximum current, give the same brightness as a run-of-the-mill LED when operated at a nominal 15 ma, but will last at least twice as long.  You have to play with the curves.

What brightness level at what lifetime are you looking for?

RE: LED life


Normally you would be sseing a LI ( Luminious intensity)
degradation of about 15 to 30 percent if you operate at Room
temp Burn in at maximum current rating of the product specs over a period of 1000 hours.
If the degradation is more than 30% eyeball judgement could
tell you cleary that the LED has degaraded and this is the
limit where most Manufacturers wouldnt want to go.
To improve the degradation (ie prevent LI loss ), I would recommend that the LED be operated at a low duty cycle 10%
to 20% with high current levels not exceeding the peak forward current of the product spec. Osram Semiconductors may include degradation curves in their product spec.
Joy to you.

RE: LED life

It depends on the LED, the way you are driving it, and somtimes (but one hope not) the way you mount it in your product.

If this is a serious concern, press the manufacturer of your device for details and life test data for the part you are planning to use.

Even though red GaAs LEDs have (in general) become pretty stable over the years, some more exotic LEDs, especially the white types, can have pretty dramatic degradation curvers. Again, the only way to answer the question is to work with the manufacturer.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close