I was reading that someone speculated that LED lamps may fail before the 25 thousand hour ratings claimed by many manufacturers. This can be caused by failure of the circuit that drives the LEDs, not the LEDs themselves. The most likely components to fail are the electrolytic capacitors, because they dry out or leak the electrolyte.
I have a few AC line powered LED lights that are inexpensive and have very simple circuitry, such as Christmas tree lights and low wattage candelabra base lights. I can tell that they have simple circuitry because when I move a pencil rapidly back and forth under the light, I can see the pencil not as a blur, but as a string of images caused by the flashing LED light.
This strobe effect indicates that the current going through the LEDs is not filtered. To save money, some makers rectified the AC but did not filter it with an electrolytic capacitor to save money. With no electrolytic capacitors to fail, the light should last longer. There could be other factors, such as running hotter, which could shorten its life. But this flickering is one way to find out whether or not the light has filter capacitors, which are usually electrolytic.
One other factor is environment. If the environment is harsh, the light may fail prematurely. If the light gets hot from direct sunlight; if the light is in an enclosure without ventilation; if the light is mounted so the heat from the LEDs rises and heats the circuitry; all of these factors may contribute to a shorter lifetime.
Some circuits are designed to slow the very high inrush current when the light is turned on. If the maker decided to eliminate this to save money, then the strain of high inrush current may cause the circuitry to fail, especially if the circuitry is is turned on and off frequently.
These are some of the factors that can influence the light’s lifetime. If the manufacturer makes a LED light that lasts for a very long time, the light will seldom need replacing and light sales will drop. So the light designer wants to design a light that lasts for a “reasonable length of time.” What is reasonable will not be known by the consumer. My guesstimate is longer than the warranty, but shorter than the lifetime of the LEDs.
