FAQ's (LED's)

1. How does an LED work?

Answer: LED means Light Emitting Diode. It is a 21st century solid-state semiconductor that was developed along with the transistors and integrated circuits now used in all our electronics.

When a positive voltage is applied to an electroluminescent semiconductor junction, the junction emits a narrow spectrum of incoherent light. The color of the emitted light depends on the composition and condition of the semiconducting material used, and can be infrared, visible, or ultraviolet.

LEDs are very efficient in their conversion of electrical energy into light, and in a proper circuit with limiting resistor will achieve about 85% efficiency. They are also very long-lived, with expected lifetimes of 100,000 hours. However, they are also sensitive to overheating and overvoltage, so the lighting circuit is more complex than a simple plus and minus.

 
2. Why does one manufacture guarantee their bulb for 50,000 hours, another for 65,000 hours and another for 75,000 hours?         

Answer: The reality is no manufacture can tell you how long your bulb will last; it depends of where and how the bulb is used. We work with many experienced engineers, the key point is not how bright the LED is, but who brings the best technology. Many people have a misunderstanding that LED’s do not radiate heat. This is incorrect, when you touch a light you may not feel the heat but the heat is dissipated by what is called a “Heat Sink.” This heat sink is typically made of aluminum or copper, but new technologies are experimenting with carbon heat sinks.

It is this inside technology and how the heat is dissipated that determines the life of the bulb. It is important to realize there is a difference in the loss of efficiency and intensity “loss of efficiency” of the LED light and actual “burn out” time. That is why when a manufacture gives you a “life expectancy” it is misleading and shouldn’t be used in your purchasing decision.

EEZRV PRODUCTS does not stop with one decision or one style. We are continually working with our engineers and the factories in order to keep up with the most recent technology so we stay ahead of the market.

3. What is a Lumin?

Answer: If you put a collector totally around a lighting device and count all the photons coming out from the device, that number corresponds to the total luminosity of the device. Any photon that is produced, goes into a dark reflector, and does not come out is not counted.

A lumen is a unit of measurement that is used to express how much illumination a source of light provides. We could get all technical here and go through the entire history of lighting, but it's really far simpler than all that. A lumen is about the equivalent of the amount of light put out by a single birthday candle if you are one foot away from the candle. A lamp that puts out 1 lumen of light is as bright as one birthday candle a foot away. A lamp that puts out 100 lumens is as bright as 100 birthday candles a foot away from you.

- Differences between a Lumen and a Watt?

• Efficiency: LEDs emit more light per watt than incandescent light bulbs^. Their efficiency is not affected by shape and size, unlike fluorescent light bulbs or tubes.
• Color: LEDs can emit light of an intended color without using any color filters as traditional lighting methods need. This is more efficient and can lower initial costs.
• Size: LEDs can be very small (smaller than 2 mm²) and are easily populated onto printed circuit boards.
• On/Off time: LEDs light up very quickly. A typical red indicator LED will achieve full brightness in under a microsecond. LEDs used in communications devices can have even faster response times.
• Cycling: LEDs are ideal for uses subject to frequent on-off cycling, unlike fluorescent lamps that fail faster when cycled often, or HID lamps that require a long time before restarting.
• Dimming: LEDs can very easily be dimmed either by pulse-width modulation or lowering the forward current.
• Cool light: In contrast to most light sources, LEDs radiate very little heat in the form of IR that can cause damage to sensitive objects or fabrics. Wasted energy is dispersed as heat through the base of the LED.
• Slow failure: LEDs mostly fail by dimming over time, rather than the abrupt failure of incandescent bulbs.
• Lifetime: LEDs can have a relatively long useful life. One report estimates 35,000 to 50,000 hours of useful life, though time to complete failure may be longer. Fluorescent tubes typically are rated at about 10,000 to 15,000 hours, depending partly on the conditions of use, and incandescent light bulbs at 1,000–2,000 hours.
• Shock resistance: LEDs, being solid state components, are difficult to damage with external shock, unlike fluorescent and incandescent bulbs which are fragile.
• Focus: The solid package of the LED can be designed to focus its light. Incandescent and fluorescent sources often require an external reflector to collect light and direct it in a usable manner.

Disadvantages

• High initial price: LEDs are currently more expensive, price per lumen, on an initial capital cost basis, than most conventional lighting technologies. The additional expense partially stems from the relatively low lumen output and the drive circuitry and power supplies needed.
• Temperature dependence: LED performance largely depends on the ambient temperature of the operating environment. Over-driving an LED in high ambient temperatures may result in overheating the LED package, eventually leading to device failure. Adequate heat sinking is needed to maintain long life. This is especially important in automotive, medical, and military uses where devices must operate over a wide range of temperatures, and need low failure rates.
• Voltage sensitivity: LEDs must be supplied with the voltage above the threshold and a current below the rating. This can involve series resistors or current-regulated power supplies.
• Light quality: Most cool-white LEDs have spectra that differ significantly from a black body radiator like the sun or an incandescent light. The spike at 460 nm and dip at 500 nm can cause the color of objects to be perceived differently under cool-white LED illumination than sunlight or incandescent sources, due to metamerism, red surfaces being rendered particularly badly by typical phosphor based cool-white LEDs. However, the color rendering properties of common fluorescent lamps are often inferior to what is now available in state-of-art white LEDs.
• Area light source: LEDs do not approximate a “point source” of light, but rather a lambertian distribution. So LEDs are difficult to apply to uses needing a spherical light field. LEDs cannot provide divergence below a few degrees. In contrast, lasers can emit beams with divergences of 0.2 degrees or less.
• Blue hazard: There is a concern that blue LEDs and cool-white LEDs are now capable of exceeding safe limits of the so-called blue-light hazard as defined in eye safety specifications such as ANSI/IESNA RP-27.1–05: Recommended Practice for Photo biological Safety for Lamp and Lamp Systems.

• Electrical Polarity: Unlike incandescent light bulbs, which illuminate regardless of the electrical polarity, LEDs will only light with correct electrical polarity.

• Blue pollution: Because cool-white LEDs (i.e., LEDs with high color temperature) emit proportionally more blue light than conventional outdoor light sources such as high-pressure sodium vapor lamps, the strong wavelength dependence of Rayleigh scattering means that cool-white LEDs can cause more light pollution than other light sources. The International Dark-Sky Association discourages using white light sources with correlated color temperature above 3,000 K.^[94]

• Droop: The efficiency of LEDs tends to decrease as one increases current.

4. How much more efficient are LED's thn other bulbs?

Answer: In the 12-volt systems of RV's and Boats, fixtures are designed to provide a specific amount of light (measured in lumens). What varies is the amount of electricity used to produce the useful light. The more heat that must be generated, the less efficient the fixture.

To a first approximation, here is where the electricity goes for various lighting. 

Thus, LEDs can produce the same light lumenocity using about one sixth or better of the power of incandescent, about one third the power of fluorescents.

Incandescent bulbs use the other five-sixth of the power it draws to heat the tungsten filament which generates infrared radiation and heat.  LEDs just do not generate all that heat. Definitely replace all incandescent bulbs with LEDs in an RV.

Halogen bulbs are touted to be more efficient than incandescent. They do this by vaporizing the tunsten instead of just heating it white hot.  For a little more efficiency you get a much, much hotter bulb.

Flourescents are a different calculation. Fluorescent bulbs are driven by a 48 volt alternating current generated by the "ballast" of the fixture. The bulbs are more efficient than incandescent, but there is inefficiency in the ballast, especially in a 12-volt DC environment.

LEDs use about 33% of the current of an equivalent fluorescent in an RV.

5. What kind of light bulb do I have?

Answer: First, determine in what kind of electrical circuit the light-bulb is used. Is it 120-volt AC or 12-volt DC or 24-volt DC?

In a USA stick-house the standard electrical circuits for lights are 120-volt AC. You may find some fixtures (especially halogens) that have an AC/DC convertor that plugs into the house circuit and supplies 12-volt DC to specialty lighting.

In most RVs and boats, all the lighting is connected to a 12-volt DC circuit. That is so you have lighting even when not connected to shore (the pedestal). There are many owners who are surprised by this fact. Only in a rare few high-end rigs is there AC lighting; these are the exception.

Some older MCI bus conversions have house circuits of 24-volt DC, and since there are few 24-volt lights, this usually requires two 12-volt DC lamps be used in series in each light fixture.

Next, take the light-bulb out of its socket and look at it. You may be able to find the bulb number printed on the bulb base or on the glass. If the bulb comes from a screw-type socket (called Edison sockets), it is probably a 120-volt AC bulb. The other most common kinds of sockets are the bayonet, wedge, and bi-pin. These are all used in DC circuits.

The base for a bayonet socket is solid metal with two little ears on opposite sides near the bottom. The following FAQs discuss different bulbs with the various bases and their LED replacements.