Insights From Leading Edge



IFTLE 98 Lester the Lightbulb vs CFL and LED : the Saga Continues

In IFTLE 63 [ see IFTLE 63, “Bidding Adieu to Lester Lightbulb] back in Aug 2011 IFTLE attempted to make the case that our little 25 cent friend Lester the incandescent bulb had gotten a bump rap as he awaited extinction on death row.

It’s not that the claims of the newer technologies (CFL and LED) using less power than incandescent bulbs are invalid, but rather what appears to be the  bold faced lie that their much greater cost is  compensated by their decades long  lifetimes that upsets all Lester supporters.

My initial rant and my follow up comments [see IFTLE 82 “3DIC at the 2011…LED testing update”] tried to point out that the testing procedures were highly skewed to make things look like these new technologies were producing bulbs that would last forever. The main issue for me was that the other components found in teardowns of the LED bulbs certainly were not built to survive the LED lifetimes that were being claimed and the new bulbs will only last as long as their weakest component.

Our installed test LED and CFL bulbs  have now cleared 650 hrs of use. Only 24,000 more hrs to go to meet specs !

First a little update on pricing as of March 2012. The CFL are down to $4 each as shown below. They are still promising 9.1 years lifetime while using ¼ the power of an incandescent bulb. Oh yes, another minor issue is that when the do burn out it is recommended that you visit the EPA site to determine safe disposal…really that’s what it says !  

(Click on any of the images below to enlarge them.)

The Phillips LED bulb ( 75W equivalent since no 100 W equivalents are for sale yet) are selling for $40 at Home Depot with an incredible “expected lifetime “ of 22.8 years. Well at least you don’t have to contact EPA to determine how to dispose of them.

IFTLE has found several more articles indicating that our concerns were/are justified. For example Bill Schweber’s guest commentary in EE Times,  “CFLs and their issues" [1/10/2012] . “My concerns are with the lies that have been told to Congress and the public regarding lifetimes of the new technologies (CFL and especially LED), and the significant increase in toxic materials associated with the disposal of these short-lived cheaply made devices.”

"Although the lifetime of the LED devices may be rated at 40,000 to 100,000 hours at an appropriate temperature, just like we have all experienced with CFLs, the actual life of the device is generally much shorter due to higher temperature of operation of the device and due to the non-LED components in the assembly. After disassembly of several failed CFL devices and some LED devices, we as a community should understand that the cheap manufacture of such devices will lead to serious pushback and disillusionment of our customers.”

"The use of aluminum capacitors in CFL and LED Edison-base devices should be avoided at all costs, and yet it seems that every CFL and LED device I have disassembled, and the photos of every such device I have seen postings of disassembly for, use cheap aluminum capacitors with low temperature ratings. As consumers, most of us are aware that the CFL and LED Edison-base devices fail rapidly in closed fixtures, in outdoor use, in refrigerators and oven use…LED power output are specified at 25° and unless properly heatsinked, the higher the temperature the less light output with aging and less service life, probably 70° max temp is acceptable, but many work above this limit, so life span is not what is publicized.”

Giving credit where credit is due, IFTLE should note that the DOE takes a  good look at these issues in their second LED report “LED LUMINAIRE LIFETIME: Recommendations for Testing and Reporting” [June 2011].

Quoting from this report : The statement “100,000 hours of LED luminaire lifetime” is gradually giving way to the realization that there is little consistency, very little published data, and few hard facts around so-called luminaire lifetime numbers…sometimes only lumen depreciation…of the LEDs is considered in estimating useful life of the luminaire product…a problem, since failure or degradation of drivers, optics, or other components can lead to  total failure. Like other parts of the lighting system, the devices and components used to convert line power to direct current suitable to drive and control LEDs affect lifetime and reliability. Capacitors, inductors, transformers, opto-isolators, and other electrical components all have different design lifetimes, are affected by operating and ambient temperature, and are vulnerable to electrical operating parameter variations from surges, spikes, and so forth. An effective LED system-reliability evaluation must take all of these aspects into consideration… Additional information that should be readily available to the purchaser, although not on the label itself, should include maximum ambient temperature of operation to achieve this depreciation performance, the number of hours actually tested on which the projection is based, and the type of projection…”

These modifications to the initial DOE report were driven by articles such as  “LED Driver Lifetime and Reliability hold thekey to success in LED Lighting Projects” by George Mao and Marshal Miles in the Sept/Oct 2010 issue of LED magazine.

Mao and Miles contend that “the light engine of properly designed LED lighting systems should last for up to 50,000 hrs. However, unless the power electronics…are designed for the correspondingly long life and high reliability, this will not be realized”   

Estimating the life of any product is primarily a matter of identifying all known wear out mechanisms and identifying the shortest lived component in the system that will render the product inoperable” Their choice for the component that would fail in the shortest time is the electrolytic capacitor. The temp that the fixture operates at appears to be a determining factor in the lifetime of such components.

Another concern is the hype surrounding how much money will be saved. IFTLE found this nifty little calculator on the Consumers Power web page. [link]  

What I have totaled up in the table below is pretty close to what power costs me in my NC home. Basically, for me , air conditioning is 75% of my power bill and even in the winter  Lester (incandescent bulbs) only account for 13 % of my power bill. 
Since this comes pretty close to my summer and winter electric bills, it shows that cutting my lighting bill by ¾ would save me ~ 36$ a year ( 3$ per month) which would pay for  less than 1 LED bulb per year and take me 25 years to break even on bulb replacement  in my house. It also confirms, for me, that in the average household, replacement of all the bulbs in the house with LEDs would not be seen on your monthly power bill. Sorry but the $3 savings will be lost in the noise.
On the country’s overall energy bill you may be able to see the effect, but on the average consumers monthly power bill, after spending $1000 to replace all the bulbs with LEDs, you will not ! The public is clearly being deceived !
Our friend Lester was set up, framed and is about to be executed for “the big energy lie” !
                                                  STOP the BS, SAVE LESTER the LIGHTBULB !
For all the latest in 3DIC and advanced packaging stay linked to IFTLE………..

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