LEDs are the best light source available, but in the RV environment they have two Achilles heels: overheating and overvoltage.
LEDs are tiny slivers of semiconductor material (pn junctions for geeks who want to know), a piece of rare earth doped silicon that mixes to emit photons in the visible spectrum as long as a suitable voltage is applied across the junction of way that a current passes through the semiconductor. Like a true diode, LEDs resist letting current flow in the wrong direction. The chemical composition of the pn junction determines the wavelength of the emitted photons, so it can have red, amber, green and blue LEDs, among others.
White LEDs are most often made using a native blue LED that shines blue photons in a phosphor which, in turn, re-emits an extended spectrum of light in a range that looks like white light to the human eye (for the geek , that’s Stokes radiation).
When comparing normal lights with LEDs, the standard incandescent bulb is only 15% efficient in converting power into usable light. Fluorescent lighting is 50% efficient at best. LEDs are 85% or more efficient at converting electrical energy into useful photons. This light source is the most efficient of all the options we have for light in our motorhomes, boats, and homes.
None of our light sources are 100% efficient; there is always some residual heat. And it is the thermal energy that destroys the light source. With incandescents, 85% of the energy wasted is heating the filament to a temperature between 600 and 1200 degrees Fahrenheit. At those high temperatures, the filament literally evaporates over time, most often in about a thousand hours, and the bulb just burns out.
LEDs are also heated by the flow of current through the circuit. The LEDs will fail immediately when the junction temperature exceeds 185 degrees Fahrenheit. Properly designed LED circuits require two very important features to be successful: overheat protection and overvoltage protection. Overheating is often related to overvoltage.
Even when an LED is operated at a carefully controlled voltage, it still generates some heat. This heat must be removed from the LED fixture at a rate that ensures that the junction temperature does not exceed the operating limit. The best way to do this is to place the LED fixture on a “heat sink” that has the ability to absorb the heat generated by the LED and move it to a location where it can radiate into the air or some surrounding heat sink. . First generation LEDs didn’t bother with this problem, as the printed circuit board they were used on was generally large enough to serve as a sufficient heat sink.
As LEDs became more advanced and more LED emitters were placed in a single semiconductor device, the problem of heat dissipation became more acute. The requirement to perform a good thermal analysis of the printed circuit board containing the LED chips became apparent to those who understood what they were doing. Others tried to use the old technology with the new chips and their products constantly failed.
The heat generated by an LED fixture is highly dependent on the input voltage to the fixture. If an LED circuit is designed to handle heat load and operate only in a 12.8 volt environment, it will not perform well in a 14.7 volt environment. It will deteriorate and die much sooner. Its lifespan will be only a few thousand hours, instead of 100,000 hours. And if the surge reaches 18 or 24 volts, the LED device can immediately turn off.
A fully charged Type 27 lead-acid battery normally provides a maximum of 12.8 volts. Some people assume it is the operating voltage of an RV. But if you connect to the Shore Power Pedestal and let your AC / DC converter charge the battery, the line voltage will increase to 13.8 volts. If you have a solar system, the controller can raise the line voltage to 14.7 volts. Battery equalization runs generally increase line voltage to 16.6 volts for two hours or more.
Most of the early designers producing LEDs for the RV environment assumed a 12.8 volt environment and their products failed at a remarkable rate in today’s RVs and boats. Some learned that if they didn’t provide some sort of voltage regulation or power regulation in their LED circuits, the product failure rates were out of sight.
How the designer protects LEDs becomes important when you are concerned about overall energy efficiency. If the LED circuit has a simple voltage limiter, it “pulls” any excess voltage, reducing your LED’s efficiency in using available power. On the other hand, if the LED circuit has a power regulator, it converts the excess voltage into usable power by taking less current from the main line. Ask your LED supplier how they are protecting their LEDs and what the cost of such protection is. Many of the LED vendors don’t understand the basics of heat and voltage issues. Will they give you a decent warranty for all conditions, like a full 100,000 hours, roughly 11 years?
LEDs are a great investment. They are expensive, but if they are built and used properly, they will have many years of excellent service and will pay back their original cost many times over. But you need to make sure that the LEDs you use have enough protection against excess heat and voltage surges that can destroy them sooner than they should.
Go for quality and request a trial and warranty.