Long live the LED! But how long is long?
LEDs have along, but not everlasting life expectancy
The main characteristic for semiconductor-illuminants (LEDs) is their long life expectancy — - as long as they are operated under very special condition. Unlike ordinary bulbs LEDs do nut suddenly fail, but gradually lose brightness during the course of their lifetime. Depending on the quality of the light-emitting diode this degradation may happen faster or slower.
Generally high-quality LEDs can reach a durability of 100,000 hours without any problems, if the user operates them in a proper manner. Proper manner means that the values stated by the manufacturer concerning current and temperature are kept. However, external circumstances like humidity or weather conditions if the LEDs are operated outdoors, may influence the life expectancy of an LED.
Life expectancy does not equal life expectancy
Talking about the life expectancy of an LED, we distinguish between medium life expectancy and service life:
- Medium life expectancy: indicates, after which period of time 50% of the LEDs of a test group failed
- Service life: indicates, after which period of time the luminous flux (lm) of an LED falls below 50% of the initial delivered luminous flux (L50)
Currently, more and more often a light-degradation of L70 or L80 is stated, which means that the manufacturer deems his LED at the end of its life, when the luminous flux falls below 70% (L70) or 80% (L80) of the initial brightness. Osram, Toshiba and Cree for example state the service life of their LED products in hours and with a degradation of 30% (L70). Usually these LED products are used far beyond this theoretical point. Depending on personal perception or area of application, several ten thousands of operating hours may pass between the L70 end of operating life and the actual uselessness of the LED or illuminant.
Example: If a manufacturer states a life expectancy of 60,000 hours with a light degradation of L80, for the end customer this does not mean that his LED will fail after 60,000 hours and is broken but that after 60,000 hours operating time this LED will „only” render 80% of the initial luminous flux, which corresponds to a loss of lumen amounting to 20%.
Quality control and continuous monitoring of the manufacturer's data at LUMITRONIX®
In our on-site LED measuring laboratory we verify technical data and carry out extensive long-term tests. This way we reach the highest professional competence and are always able to recommend our customers the most durable, most efficient and brightest products without having to rely on the data stated by the manufacturer.
Example: Philips Master LED BirneGlow E27 12W (item no. 71682)
In order to provide our customer with a possibility to compare, we have integrated a savings calculator into our shop, which gives some indication on possible savings when using the selected LED product compared to an ordinary bulb. This way the customer receives an idea about efficiency and payback period of our LED products. At the same time our savings calculator represents an aid for our customers, since they can assess the data of life expectancy of various manufacturers better and faster in terms of cost saving. In our shop you will find the savings calculator with every product in the category LED lamps and luminaires. Just enter the data concerning life expectancy, performance and price of your old bulb and the calculator calculates your individual cost savings when buying the product selected by you.
Warranty or guarantee?
The so-called Gewährleistung (warranty) is required by law and legally binding for all dealers. In the event of a warranty the seller is responsible that at the time of sale the product is free from material and legal defects. This means that the product must provide the contractually stipulated condition. Furthermore, advertising messages must apply and delivery must be complete in terms of quantity. In the event of a flaw, however, the onus lies with the purchaser. In accordance with § 437 of the German Civil Code (BGB) since January 1, 2002 legal warranty amounts to 24 months, in the case of used goods it can be decreased to 12 months in the general terms and conditions or individual contracts. Thus the customer can assert his rights upon delivery of the flawed item for two years now (or one year in the case of used goods, as far as contractually agreed). For the benefit of the customer in the first six months after the transfer of risk it is assumed that the item has already been flawed at the time of delivery, unless the seller can prove that the flaw did not exist at the time of transfer. In many cases it will be difficult to furnish this proof. In practice this means that after the expiration of six months the warranty right can only be asserted in rare cases and the customer as a rule depends on the dealer's goodwill.
A Garantie (guarantee) is a voluntary service of the seller. The seller guarantees that the sold item provided a certain condition at the time of the transfer of risk or that a certain condition will last for a stipulated period of time (so called guarantee of quality or guarantee of durability, see § 433 of the German Civil Code). It is up to the manufacturers whether or not they provide a guarantee in addition to the statutory warranty.
Service guarantee of the LED manufacturers
provides a 3-years-system guarantee on LED modules used together with Optotronic operating devices, which are operated properly and in accordance with the technical data stated by Osram. To make use of this service guarantee, the customer must register at Osram after having put the system into operation.
provides a 3-years-system guarantee on all LED systems consisting of LED modules, LED components, LED strings and LED drivers by Philips and which are operated properly and in accordance with the technical data stated by Philips. To make use of this service guarantee, the customer must register at Philips after having put the system into operation.
provides a 3-5-years-guarantee on all LED products, depending on product and life expectancy (www.cree.de)
provides a three-years-guarantee on all LED products (www.toshiba.de)
Handling at LUMITRONIX®
We have made a customer-friendly concept of handling this topic our philosophy. If a customer makes a complaint about an item, we will always feel obliged to satisfy him or her. We offer our customer solution possibilities that go beyond de facto existing claims. In order to build-up confidence, we provide a five-years-guarantee on many of our products. We are able to provide such a long guarantee, because we only use raw materials of the highest quality for our products and design and manufacture almost all of these products in Germany.
In those rare cases when a customer asserts a guarantee claim against us, we decide on a case-by-case basis and consider many factors like expectations in the product and price-performance-comparison (see Nichia)
In principle, however, it must be said that beyond the statutory and manufacturer's provisions we can only act within the scope of goodwill. Particularly attractive for our customers is also the fast and easy handling of complaints by our company: all necessary instructions are available on our website, where you can also print your parcel label for the free return.
Christian Hoffmann,LUMITRONIX® Managing Director
Thanks to thousands of product tests and millions of installed and sold light emitting diodes, we know the topic of life expectancy very well and would like to share our very personal and also subjective impressions:
Despite contrary datasheets and elaborate item description advertising, classical 5mm LEDs will only in exceptional cases last longer than 3,000h - unless it's a brand product. Particularly Nichia LEDs also in reality can reach 100,000h and more. Fewer mistakes can be made with SMD and High-Power LEDs. Their life expectancy is usually considerably longer. Almost all High-Power LEDs of the renowned manufactureres (Cree, Osram, Nichia, Seoul, etc.) reach at least 50,000h and more.
My conclusion: Do not buy any LEDs if you do not know the manufacturer. We have gained very good experience with Osram, Cree, Nichia, Toshiba, Seoul, and for some time again also with Lumileds Luxeon. LEDs of unknown manufacturers may include some bargains, but you always buy a pig in a poke and only know in retrospect whether the purchase was worth it. In average, the latter does not apply to no-name products: half price, but only a tenth of the life expectancy.
Tips for improving the durability of your LEDs
- Electrostatic discharges may harm LEDs. Handle your LEDs in an ESD-compliant manner
- Do not solder your LEDs too hot or for too long
- Do not touch the LED. Even the slightest dirt residue may decrease efficiency and heat conductivity.
- LEDs must not overheat. The rough guide for many high power LEDs is: a 10°C lower junction temperature increases life expectancy by 10,000h. Please consider active or passive cooling, depending on performance, and allow air convection.
- Only operate LEDs and components within the typical specifications, if possible, and not to the maximum