IFTLE 98 Lester the Lightbulb vs CFL and LED : the Saga Continues
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.
"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.”
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…”
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]