In late 2009 I obtained a few dozen of these 10mm 1 watt single chip white LEDs from a Chinese vendor on eBay. My main intent was to see how long they would last in a lifetime test. I attached four of them with screws and washers to a piece of wood, and connected them in series and up to a 9V AC ‘wall wart’ adapter. I measured the current at about 130 mA – the current varies a bit with the AC line voltage. The LEDs are 1 watt, and should be able to handle over 300 mA, but they are running at less than half that in this test. The washers and screws act as heatsinks and the LEDs run warm but not hot.
I used these as a rather bright night light but left them on 24/7 with the exception of a very few power outages from November 7, 2009 until this summer 2012. In this photo they are all four powered on and putting out what little light they have left after a few tens of thousands of hours. When they were first powered on, they were very bright and would have shown four bright spots in the surface in front of them, easily overpowering the light from the camera’s flash. Now the four spots are not even visible, masked by the camera’s flash. In my old blog I showed a picture of them pointed at the wall, along with the exact same LED, but new and unused. The single new LED was much brighter than all four of these LEDs, showing that these have lost most of their light output over the 3 plus years they have been left on. I can look directly into the lens and see the chip without eye strain, because the light output is so dim. I would estimate they have lost 90 percent or more of their light output, but I can’t give an accurate amount because I did not have the luxmeter at that time. My conclusion is that they were relatively inexpensive and unfortunately I got what I paid for.