How the ‘LED lighting backlash’ could be good for the industry
Early issues concerning light quality have largely been solved in all but the cheapest LED products and the (relatively high) initial purchase cost of LED bulbs has been literally decimated in the last six years. As a result the LED lighting market, which was worth $4.8bn in 2012 is predicted to grow by 45% per year to $42bn by 2019.
Regardless, all technologies will have their detractors. As a recent example, Scott Elder of Linear Technology stated that, although LEDs claim a lifetime of tens of thousands of hours, most will actually fail well before this. This, he claims, is the ‘big lie’ of LED lighting. It’s an alluring argument. However, in my estimation, it just doesn’t add up.
If you look at his working-out Scott assumes that the ‘circuit elements’ in traditional bulbs and LEDs fail at an equivalent rate. More ‘circuit elements’ (such as the separate components of a driver circuit) lead to a higher failure rate, he claims. However, it’s hardly sensible to compare the ‘circuit element’ of a piece of tungsten (heated to the point that the wire evaporates) with relatively cool-running silicon connected by copper circuits. According to this same working out I’m pretty certain that a standard PC would fail almost as soon as you got it home!
The rest of Scott’s ‘proof’ is purely anecdotal. ‘Seven out of twelve’ of his wife’s expensive LEDs, he says, have failed, though he makes no reference to brand, the timeframe over which the LEDs have failed, or the conditions in which they were operated. My own anecdotal riposte is that I have only had one LED out twelve in my house fail over a number of years, and that was from a batch of extremely cheap, low-end LEDs.
However I think Scott’s right on one point: It may be beneficial to look at the ‘total circuit solution’. Perhaps we should ask manufacturers to put their money where their mouth is in terms of guaranteeing an overall package lifetime?
Thermal management is the most critical element in maintaining an LED’s lifespan. This is especially true as you start to move into High Brightness LEDs (such as those used in automotive headlights, warehouses, spotlights, UV, etc). Early LED designs were often hampered by a poor understanding of the thermal requirements of electronics and would often run unacceptably hot, drastically affecting lifetime. Components would wear out due to heat stress, or simply ‘pop out’, leading to unacceptably short lifespans.
While largely unverified concerns over LED lifetime are overstated, the industry could perhaps use this point in time to address lifespan concerns once and for all, claims Ralph Weir, CEO, Cambridge Nanotherm.
Nowadays thermal management has improved enormously. Today it is not uncommon for both domestic and HB LEDs to be rated at 50,000 hours, and with higher-intensity UV lights to achieve up to 30,000 hours, much higher than was ever previously possible, and LEDs are being used in some of the most demanding and high-reliability applications. What’s more, better thermal management can allow manufacturers to use fewer, but brighter, LEDs in a design, reducing the overall cost and allowing them to afford better-quality driver components.
However, as the price war heats up across the LED market, it’s very possible that cheaper bulbs across the industry might cut corners on elements such as thermal design or other components, adversely affecting the overall ‘real’ lifetime of their product. This, in turn, would erode confidence amongst customers.
In order to avoid this, this might be an opportunity for the industry to improve how it describes the lifespan of its products. At the moment many LEDs come with a guarantee of a couple of years, and the EU is stipulating that any domestic LED bulb must last a minimum of 6000 hours. Perhaps the industry could go further? Whether we’re talking about domestic or HB LEDs, perhaps the industry should be called upon to guarantee whatever lifespan is stated for the overall bulb package? Standardized guarantees of this sort could lead to more trust amongst customers and should ensure that the reputation of LEDs in future is not affected by any ‘rush to the bottom’ in terms of price and quality.
About the author:
Ralph Weir is CEO of Cambridge Nanotherm – www.camnano.com
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The big lie about LED lighting
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