What About White LEDs?
White LEDs have been making slow but steady progress, and we believe that they are now suitable for interior marine lighting applications. We've been testing and building prototypes for over ten years, and they finally have reached the point where they are good enough for use in Alpenglow Lights.
Efficiency: The amount of hype and misinformation surrounding white LEDs has been truly amazing. It's not uncommon to see statements like "twice as bright, but use one-tenth the power." In other words, they are claiming that they are 20 times more efficient. The truth is that the very best white LEDs are 4 to 5 times the efficiency of incandescent lights. That means they are similar in efficiency to compact fluorescent (CFL). In applications where the light can be directed in a specific general direction, LEDs can have some additional efficiency benefits because there are less losses from reflection within the fixture. This is especially beneficial in something like a reading light IF the LEDs used are directional. If you use the type of retrofit bulb that has LEDs shining in all directions, you are requiring most of that light to be reflected, and will lose much of the benefit.
Color: Color has long been a problem with white LEDs. They were usually a very cold, almost blue, color. Although many available lights and retrofit bulbs still use LEDs that are too cool in color to provide a pleasant light, warmer LEDs are now available. It helps to understand something of how white LEDs work. LEDs produce light of a single wavelength. In other words, a single color. White light is a mixture of colors. So, how can LEDs make white light? The answer is "they can't." They are actually a high-intensity blue. In order to get white, they add a phosphor (like used in fluorescent lights). The blue LED light excites the phosphor, causing it to glow yellow. And the mixture of the blue and yellow results in white. By varying the mixture of blue and yellow, as well as using phosphors of varying shades, the resulting color can be controlled. Because the light is made up of basically just two colors, the spectrum isn't complete. Even though the overall light color may be warm, there are some colors that aren't well represented, so some colors can look dull compared with other sources of light. Compact fluorescent (CFL), in contrast, use three phosphors, which results in a more complete spectrum. Some LED manufacturers are doing a better job of getting acceptable color than others — we use only warm LEDs from those producing the best. Our LED color preference is a 2700 Kelvin rating for a soft, warm color.
LED Retrofit Bulbs: There are many retrofit bulbs on the market for converting incandescent or halogen lights to LED. Except for low power applications, they don't work very well for several reasons. High-power LEDs produce a LOT of heat. Although the temperature is much less than a light bulb, it is concentrated in a very small area, and LEDs are semiconductors which don't like heat. The higher the temperature, the shorter the life. The severe size limits placed on retrofit bulbs result in undersized heat sinks and using a minimum number of LEDs driven at or beyond their design limits. Reports of burn-out in less than 2000 hours are common. The heat sink requirement means that the better designed high-power LED bulbs are often too large and heavy to work well in many applications. There are lower power retrofit bulbs that look like a regular light bulb with many LEDs inside. These can work very well for some low-power applications like anchor lights. Also, certain LED bulbs designed specifically for use in running lights can be very beneficial. Alpenglow design is the opposite to that of retrofit bulbs. By making the LEDs an integral part of the fixture, we are able to drive the LEDs at half of their maximum design limit! We use either the entire fixture (Reading and Berth Lights) or the complete back assembly (Overhead Lights) for the heat sink, resulting in much lower LED temperatures. The overall benefit is much longer life!