LED lights are often advertised with a very long lifespan of many thousands of hours. On some packaging there are indications of 10, 20 or 25 years. In this article you will find out what is behind the great advertising promises of the manufacturers.
- General information about LED lifetime
- Lifespan Comparison
- What causes an LED lamp to fail?
- How accurate are the manufacturer’s specifications?
- What do 20,000 lighting hours really mean?
General information about LED lifetime
The actual light source in every LED lamp is the LED itself. An LED (light emitting diode) is a semiconductor light source. With current manufacturing processes, LED’s can be manufactured with a lifespan of 100,000 hours and more.
Comparison with old light sources
The old halogen or energy-saving lamps were used in a way until they suddenly burnt- out and had to be replaced one day. The special thing about LED’s is that they do not simply fail. With an LED, the brightness slowly diminishes in the course of operating time.
When the brightness decreases, the luminous flux (lumen) decreases. This is a slow process and is hardly noticeable in practice. A difference would only be visible if one of two LED light sources had already had several 1,000 operating hours behind it and this was compared with a new identical lamp.
Further components of an LED lamp
In addition to the light source in the form of one or more light emitting diodes, an electronic circuit is also built into an LED lamp. This component is often referred to as an LED driver. The driver is necessary to generate the DC voltage required for the LED with a constant operating current from the 110V AC mains in the household.
This circuit consists of individual electronic components such as capacitors, rectifiers and transformers. If an LED lamp suddenly fails, it is usually due to a defect in this circuit. With high-quality LED lamps, however, the LED driver usually consists of durable components to prevent premature failure.
In this table you will find a comparison of the average lifespan of different lamps. The middle column shows the lifespan in hours. The right column shows the approximate burn time in years with a daily burn time of 3 hours.
(with 3 hours/day)
|Incandescent bulb||1.000 h||1 year|
|Halogen bulb||2.000 – 4.000 h||2 – 4 years|
|Eenrgy-saving bulb||10.000 h||9 years|
|LED bulb||15.000 – 50.000 h||14 – 45 years|
How is the lifespan of an LED lamp indicated?
The actual light source (light emitting diode) within an LED lamp lasts very long with theoretically 100,000 operating hours and more. However, the lifetime of the LED driver is lower and thus determines the actual lifetime of the entire LED lamp. Apart from the operating hours, the number of switching cycles and the ambient temperature have the greatest influence on the durability.
In many cases, instead of operating hours, we also talk about lighting hours. Both of them mean the same thing and indicate the number of hours in which the LED lamp is switched on. Usual LED lights are designed for 15,000 to 50,000 lighting hours. This information must always be indicated on the packaging.
The number of switching cycles determines how often an LED lamp is switched on and off. With normal room lighting, there are only a few switching cycles per day. With staircase lighting, however, there can be many cycles per day if the light is switched on and off each time.
Usually 20,000 to 100,000 switching cycles are normal here. This information must also be stated on the packaging.
Due to their high efficiency, LED lamps have significantly less waste heat than old lamps. Nevertheless, there is also a certain amount of power loss here, which must be dissipated as heat. If the ambient temperature is too high, the LED lamp ages faster. Both the LED itself and the electronics integrated in the lamp suffer from excessively high temperatures.
The normal LED lamps are basically designed for operation at normal room temperature. It must be ensured that the LED lamp is installed in such a way that normal air circulation is possible.
What causes an LED lamp to fail?
Of course, there can also be the famous lemon LED lamp, which fails after a short time. However, if the purchase is based on well-known and proven brands, this is the exception.
If the number of lighting hours specified of the lamp is exceeded, the lamp usually shines somewhat darker. However, the most common reasons for a defect are too many switching cycles or a too high ambient temperature.
Many switching cycles
A frequent cause of many unnecessary switching cycles is an incorrectly set motion detector. The specification of 15,000 switching cycles when purchasing an LED illuminant initially sounds a lot. However, if the motion detector is extremely sensitive and set with a very short light duration, the connected lamp is constantly switched on and off.
Although the number of operating hours remains low, very many switching cycles occur in a short time. If the LED lamp is switched on 20 times per night for one minute at a time due to the wrong setting, the 15,000 switching cycles are already reached after two years and the lamp could fail shortly afterwards.
It would make more sense to set the sensitivity of the motion detector correctly and increase the light duration to 10 minutes, for example. If the lamp is switched on only 4 times per night, the maximum of the switching cycles would only be reached after 10 years.
High ambient temperature
Another frequent reason for shortening the lifespan of an LED lamp is a too high ambient temperature. LED luminaires are generally designed in such a way that sufficient cooling surfaces are available. However, if the luminaire is mounted in a small corner, heat accumulation can occur.
The conversion of an existing lamp to LED illuminant in most cases is no problem. However, there are also lights with very narrow lamp glasses, which leave only little waste heat outside. The glass should not become so hot from the outside that it can no longer be touched. Otherwise, the lifespan of the LED light will be shortened in any case.
How accurate are the manufacturer’s specifications?
In commercials or on packaging, LED lights are often advertised with a very long LED lifespan of 10, 20 or 25 years. However, this information is of little importance, as only a few operating hours per day are assumed here. Much more important are the manufacturers’ mandatory specifications on switching cycles and the number of lighting hours.
In the case of cheap no-name lamps, however, the information is of little significance. One drives better with high-quality LED lamps of well-known brand manufacturers. Due to the strong competition in the LED sector, they simply cannot afford to advertise with fantasy values.
Test in the laboratory
In addition, the manufacturer’s data on switching cycles and light duration are examined in test laboratories. The switching cycles can easily be checked with a corresponding test setup by automatically switching the lamp on and off again and again until the defect occurs.
The light duration cannot be tested directly, because a lamp with a stated 50,000 operating hours would shine for almost 6 years without interruption. This is much too long for a test. Therefore, the lamps are only tested for a few 1,000 hours, but under more severe environmental conditions such as increased temperature and humidity.
The results are then extrapolated. A lamp life of several 10,000 hours can nevertheless be simulated with a relatively short test duration.
What do 20,000 lighting hours really mean?
With 20,000 lighting hours is meant that the LED lamp with a high probability actually illuminates at least 20,000 hours. This example shows how many 20,000 hours can actually be in practice.
Example: Lifetime of a living room lighting system
In many households, an LED lamp in the living room is switched on for an average of 6 hours a day during the winter months. In the summer months, the lamp is either not switched on at all or is switched on for a maximum of 2 hours a day. This results in 1460 lighting hours per year.
6 months x 6 hours + 6 months x 2 hours = 1460 hours per year
20,000 operating hours / 1460 hours per year = 13.7 years
This lamp could therefore achieve a lifespan of almost 14 years. Possible absences such as holidays or other leisure activities reduces the number of annual operating hours and further increase the lifespan.
The lifespan of LED lamps has increased many times over compared to old light sources. This justifies the seemingly higher purchase price at first glance. When you buy LED lamps from well-known brand manufacturers, you can rely on the specified information about lifespan.
If you then buy an appropriate LED lamp with a proper number of switching cycles and lighting hours depending on where it is used, you will have peace of mind for many years. The regular replacement of defective lamps is no longer necessary.