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Technical Lighting Help

Buying Cheap Will Cost You!

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A recent Wall Street Journal article (Why LED Bulbs Don’t Always Live Up to the Hype About Their Life Span – Jo Craven McGinty 10-1-2021) detailed some of the frailties surrounding expected lifespan of LED light bulbs. Unfortunately, they failed to discuss a crucial element that is now leading to shorter lived lamps…the desire for cheap.

The reporter talked to the Director of Research at the Rensselaer Polytechnic Institute and he clearly defined the reasons for lower longevity. There is, however an underlying reason for his recommendation to use “LED System Life” rather than LED life as a better way to measure expected life. Multiple reports and investigations indicate failure is most likely to occur in the driver and electronics. The LED have proven to be very effective and hardy, failing at a very low rate. A quick overview by the DOE https://www.energy.gov/sites/prod/files/2014/04/f14/life-reliability_fact-sheet.pdf helps us to understand the conclusion delivered by Rensselaer.

Consumers were never able to justify a light bulb that cost tens times a conventional incandescent lamp. Initial sales were poor. At those prices, efficiency needs would not be met.

One of my favorite jokes tells the story. A kangaroo walks into a bar and orders a martini. The bartender prepares the drink and places it on the bar. “That will be $35.” The kangaroo pays the bartender and the bartenders comments, “You know, we don’t get many kangaroos in here.” The kangaroo responds, “At these prices, I’m not surprised!”

To make LED lighting more acceptable to the greater kangaroo population, they had to be cheaper. That means money needed to be extracted from the components and manufacturing process. Using high quality LED, electronic circuitry, drivers and a strong deference to thermal management, the original LED would last far longer than the advertised 50,000 hours. Cheaper electronics, disregarding heat or combining circuits on a common board all make the light bulb less expensive, but at a cost to longevity.

There is a wonderful analysis conducted by the website “Hackaday” that tells this tale. By analyzing the components and construction of three readily available LED lamps, understanding “you get what you pay for” is easy.

To paraphrase the research, a very inexpensive lamp combines the LED and driver on a single board. (There are other electronic and wiring variations I will not recount.) With inexpensive components, wiring and assembly, this lamp promises a life of 7500 hours. The second lamp is a bit more expensive and the life expectancy is doubled to 15,000 hours. This is accomplished by separating the driver, thereby protecting it from the heat and delivering an incrementally better product. The best of the three tested light bulbs separates the driver and LED and uses superior capacitors rated for higher temperatures. (There are other improvement as well.) The price is the highest of the three and it lasts the longest, at a promised 25,000 hours. If longer lasting light bulbs are desired, they can be had, but it will cost more.

(If desired, you may read the full report here: https://hackaday.com/2019/02/05/what-happened-to-the-100000-hour-led-bulbs/)

LED System Life should be the barometer of the future. The reality of our desire for cheap, cheaper and cheapest has forced a realignment of expectations for LED. It is a shame that the LED is getting the bad name.

2 replies on “Buying Cheap Will Cost You!”

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