Wednesday, March 11, 2009

The Good the LED and the Ugly


A (somewhat) critical look at
LED Replacement Lamps
for Domestic and Business Applications


This post is by way of an introduction to several posts I intend to publish on LED lighting. I hope to give some comparative feedback on products I have tried myself, and I hope to give some illustrative comparisons between types of lights.

There has recently been what can only be described as a flood of LED replacement lamps on the market purporting to be direct replacements for existing bulbs. The most common offerings in this respect are replacements for the small spotlights found in down-lighters, ceiling spots, etc. The types most commonly found in Ireland are the 12 volt MR16 or the mains voltage GU10 type bulb.

The MR16 and GU10 LED replacement lamps tend to come in two general types; one with lots of little LED bulbs packed together, and the other with one or more larger LED elements mounted on a metal heatsink and generally using a lens to focus the light.

I have tried several of both types, and can say that the quality varies a great deal indeed. LED lamps are far – far from being a well developed consumer product – it is really not a time to rush out and buy lots of LEDs. The type most likely to be a cause of great of dissatisfaction is the multi-led type of bulb. I have been testing one such bulb, and after only a couple of hundred hours of use it has lost about 50% of its brightness – it is a total dead loss!!

I came across a very interesting article by Kevin Willmorth of Lumenique , in which he authoritatively discusses the serious shortfallings of the tiny 5mm LEDs used in many of these bulbs.

Here is an extract (a large one!) re-published with permission:

5mm LEDs Generally Unsuitable for General Illumination
Posted in Reviewed - Poor Performers by kwillmorth on November 30th, 2008

The 5mm LED has been around for a very long time. These are the small LED “lamps” found in virtually all low quality and novelty LED products.

For general illumination, where demands for significant lumen output, long service life and consistent color and lumen output are necessary, the 5mm LED is simply inadequate to the task. The large number of low end products on the market using 5mm LEDs marketed with unsupportable performance claims and very poor performance makes sorting the good from the bad is virtually impossible. Because of this, the best approach is to reject all products using this form of LED outright in favor of packaged LED products.

Customers perceptions formed from disappointment with the performance of low quality 5mm LED products will hurt the entire LED market, and slow adoption overall.

Packaged LED devices, or “lamps”, mounted to proper metal clad circuit boards and thermally inductive heat sinks will out perform 5mm LED devices in lumen output, lumen maintenance, and service life, by a large margin.

Unfortunately, counterfeit LEDs that are made to look like quality products have begun to infiltrate the market. However, when compared to the volume of poor performing 5mm LEDs in the market, the best bet is to select a product using packaged LEDs.

For energy savings, the only value products that depend on 5mm LEDs offer is low total wattage. These devices have an efficacy that is no better than incandescent lamps, and far less than fluorescent, regardless of claims made on packaging.

rapid degradation of light

The reality is that virtually all of the claims of energy saving are based on the low wattage rating of the products, and not on actual equivalent light output. Virtually all claims of improvement over fluorescent lamps are false, as the 5mm LED is simply not able to produce the same lumen output, and rarely equal life. Claims to equal the light of MR16, PAR and R lamps in output are dubious, and based on initial values only, and are always overstated. As the product is put in use, the rapid degradation of light output will soon degrade their serviceability.

Packaged LED devices, with proper thermal control, offer a significant performance advantage over 5mm LEDs, incandescent, halogen, and many CFLs, along with far longer life, greater lumen maintenance, superior optical control, and far greater color consistency. For energy efficiency applications, there is no better choice than high quality, high and medium output packaged LED devices.

The graphic (above) illustrates the range of performance one can expect from 5mm LEDs (yellow area), and high brightness packaged LED devices (blue area). Where typical 5mm LEDs will have lost 50% of their light at around 8,000 hours of life, HB packaged LED products will maintain 70% of their light output at 50,000 hours.

The original article can be found here:

Its author Kevin Willmorth’s contact details are here:

Kevin Willmorth
Lumenique, LLC
N112 W16298 Mequon Road, No 120
Germantown, WI 53022


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