LEDs have made quite an impact on the boating industry. Their small size, cool operation, and low power requirements combined with their excellent durability makes them an ideal choice for boaters looking to improve the performance of their lighting systems. However, while many boaters are already quite familiar with just how effectively LED spots can lower energy consumption and reduce maintenance costs, far fewer really have any idea of just what an LED actually is or how it achieves such great performance. LEDs actually represent a radical departure from our traditional lighting technologies, and here we’ll go over just what these differences are and what makes up the design and construction of the humble LED.
LEDs operate in a manner completely different than that of incandescent light bulbs. Incandescent light bulbs create light by heating a filament within a sealed glass globe until it radiates energy in the visible band of the electromagnetic spectrum, otherwise known as light. This is a very inefficient process as a great deal of waste takes place in the form of energy being radiated as heat, up to 90%. In this process, materials radiate light energy as an electrical current is passed through them, usually a semi conducting material. As electrons pass through the material they go the a process of radiative recombination and pass through microscopic holes in the material, causing them to become excited and release some of their energy in the form of photons, or light. This process produces little heat and is very efficient as the energy released is along a very narrow band of the electromagnetic spectrum, mostly in the visible wavelengths range.
This design is simple, cheap, and easy to produce, which is in large part responsible for the great popularity the standard light bulb has enjoyed for over 100 years. However, this design is also extremely fragile and susceptible to damage from impacts and vibration, and has a relatively short operating life due to the fast degradation of the filament which occurs due to the extreme temperatures it is subjected to.
LEDs resemble solid state electronics more than they do a light bulb, and in fact are known as solid state lighting devices. An LED consists of very thin layers of semi conducting materials sandwiched together, with two electrical contacts called an anode and cathode which connect to different layers of the semi conducting material, all of which is seated onto a flat backing plate or platform usually comprised as a part of the cathode. The entire assembly is often encased within an acrylic shell to protect the LED from damage and help direct the light being radiated.
As can be imagined, LEDs are more difficult and more expensive to produce than a standard light bulb, which drives up their cost. However, although they are costlier to produce, their high efficiency, long operating life, and very high durability helps to offset the higher cost of this more expensive design.
There are many ways in which lighting efficiency is measured. The most basic standard involves comparing the total lumens produced by luminaire to the number of watts consumed. This is effective for measuring total output produced, but for practical purposes does not accurately indicate how effective a lamp is at illuminating a specific area. Since that kind of performance measurement takes into account factors such as lamp and reflector design, we’ll leave that for a later discussion.
Regardless, considering total lumen output, a typical incandescent bulb produces 15 lumens per watt. This is because as described earlier, the incandescent produces light by heating a filament until it radiates energy in the visible portion of the electromagnetic spectrum. For an example, consider if you briefly heated a nail with a torch. Once you remove the torch from the nail, you could place your hand close to the nail and feel energy radiated from it as heat, but you would not be able to see this radiated energy. Now, if we were to keep the torch on the nail for a longer period of time, the nail would glow red, and we would then be able to see the energy being radiated. If we held the torch to the nail long enough, it would glow bright orange, then yellow, then white. This is precisely how a light bulb filament produces light, and why it is so inefficient.
As little as 4 years ago LEDs were limited to producing about 60 to 80 lumens per watt. LED technology is quickly advancing however, and today LED developers and manufacturers like CREE and GE are producing LEDs that in testing are reaching 200 lumens per watt! Today LEDs suitable for commercial use average approximately 80 lumens per watt, making them as much as 5 times more efficient than incandescent light bulbs. So, we could say that we could replace a 100 watt incandescent light bulb producing 1500 lumens with a 20 watt LED fixture producing 1600 lumens, and actually produce more light using only ¼ the amount of electricity.
By now the advantages LED hold should be fairly obvious and demonstrate why they are becoming so popular within the boating industry. There are limits however, and LEDs still require some development before they can work effectively in every role. LEDs for instance are not as effective at throwing a light beam for long distances, although developers have indeed closed this gap and produced LED spotlights of impressive power and reach. LEDs also require very precise and steady voltages in order to reach their maximum potential. LEDs can withstand working with too low a voltage, but voltages that exceed their limits can cause them to burn out very quickly, and voltages that fluctuate too much can reduce their performance and lifespan significantly. As a result, LEDs also require supporting electronics that can maintain voltages at safe and reliable voltages.
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