Thanks to AT&T discontinuing Web hosting, all the links to my charts will soon be broken.:thumbsdow With new hosting, I will continue the updates to the lumen depreciation tests here.
Nichia GS: After 3000 hrs at 30ma it has dropped to 76% of initial output. The drop started before 1500hrs and has been a steady, almost a linear decline. I expect it to drop below 70% at around 3500hrs.
3-18-10 update: 3384 hrs. The GS seems to have stabilized. Perhaps it is not done just yet. This will be interesting.
4-19-10 update: 4152 hrs. The GS dropped a little. it is now at %72 of initial intensity. It is in danger of dropping out of the test soon.
5-18-10 update: Nichia GS: Output has dropped to below 70%. It lasted 4,800 hrs at 30ma. At 15ma, I'd expect life to be at least 20,000 hr. Test completed.
Radio Shack 276-0017 neutral white 30 Deg LED. After 3000hrs at 30ma, there has been a small decline, however it is still at 102% of it's initial brightness. When a decline starts after thousands of hours of steady state output, means it has began its decent into the valley of the dim LED. It is too early to estimate when it will drop to below 70%.
3-18-10 update: 3384hrs. The RS LED also seems to have stabilized (slight brightness increase).
4-19-10 update: 4152hrs. Not much change. Steady as she goes!
5-18-10 update: 4848hrs. This LED shows no quit. Steady state.
6-18-10 update: 5592hrs. Slight drop but still above initial intensity.
8-19-10 : 7080hrs. No change from last measurement.
10-10-10: 8328hrs. No change. LED has been in overdrive for almost one year now. At half current, life is at least 4x, so it would last at least 4 years at 15ma. Since the LED has spent the last 4 months at steady state, I'd venture to guess that it will last 50K hours at normal drive currents.
10-26-11: 17472hrs. LED remains above initial brightness after 2 years. At this point I consider the test over.
Cree 503C-WAS-CBADA151 This part no. specifies a wide brightness and tint, but they all have been about the same brightness and tint (sample of 110 pcs). After 2000hrs, it has been a roller coaster ride of luminance, but at least it has not started to decline. The blue line is an older Cree LED. The newer 503 series is brighter and longer lasting.
3-18-10 update: 2328 hrs. The Cree just wants to get brighter. Interesting.
4-19-10 update: 3096 hrs. Notable drop, but it is back at initial output. Not sure if it is fading or just a momentary dimming. Odd how the LEDs vary over their life. I have seen this oddity in other tests not performed by me.
5-18-10 update: 3792 hrs. Trend seems to show it is now on the decline but still at 92% of initial intensity.
6-18-10 update: 4536 hrs. Falling fast and now at 70.5% of initial output. It is safe to say this LED will drop below 70% in the next couple of days. Interesting fade characteristic as compared to the GS. The GS started loosing intensity just before 1,500 hrs and slowly declined. This Cree gained intensity which peaked around 2500 hours and then started fading at a higher rate.
6-22-10 update: 4632 hrs. As expected, the LED has fallen into the 69% range. The reason for fading seems to be the discoloring (slight darkening) of the epoxy and/or the phosphors above the die. I doubt the die itself lost output. At 15ma, I'd expect the LED to last at least 20K hrs. Like the GS, this is excellent life for a 5mm LED. Test completed.
jtr1962 was kind enough to send me some surface mount LEDs for testing. These are tiny, but with masking tape, they are fairly easy to solder onto a perf board (the kind with the ring of copper around the hole).
The Osram LW E6SG PLCC4 (on Left in above photo) has been cooking at 39ma for 1680hrs and has been pretty much steady state. These have a nice near neutral white tint.
3-18-10 update: 2088 hrs. Very slow but steady decline
4-19-10 update: 2855 hrs. Now steady state. For 39ma, this LED has held up well.
5-18-10 update: 3551 hrs. Remains steady state. Amazing LED to handle 39ma so well.
6-18-10 update: 4295 hrs. Seems to be starting to descend.
8-19-10: 5783hrs slight gain in output. So, after falling a bit, it has stabilized.
10-10-10: 7031hrs. Slight drop. Still at 86% initial intensity.
10-26-11: 16175hrs. LED fell to 80% of initial brightness. At 39ma for nearly 2 years and well above 70% of initial brightness, the LED is made for the long haul. At this point, I consider the test over.
The smaller Nichia (not charted yet) is just a bit less bright and cool white. It is testing at 30ma and after nearly 600hrs has not changed
3-18-10 update: 984 hrs. Now added on chart. starting to decline.
4-19-10 update: 1752 hrs. After starting to drop, it has regained steady state output.
5-18-10 update: 2448 hrs. Starting to decline. Now at 80% intensity.
6-18-10 update: 3192 hrs. Dropped below 70% of initial intensity. Not bad for such a tiny LED. Test completed.
This is a reminder of how pathetic those cheap ebay/Chinese LEDs are. This one fell below 70% in about 3 whole days at 30ma
I decided to make it easier on the cheapo ebay LEDs. I tested them at 12.5 ma. They lasted about 500 hrs. Hey! that is 3 weeks of use!
I point out this junk because they end up in many products from cheap flashlights, to "shower head" PAR styles lights, landscape lighting and under cabinet lights. A new Menards store opened nearby and some LED lights on display were faded in 1 month!
Coming up: I have some Fox Group 360nm UV LEDs on the way and I started testing some Cree low dome 5mm 110 Deg LEDs.
Nichia GS: After 3000 hrs at 30ma it has dropped to 76% of initial output. The drop started before 1500hrs and has been a steady, almost a linear decline. I expect it to drop below 70% at around 3500hrs.
3-18-10 update: 3384 hrs. The GS seems to have stabilized. Perhaps it is not done just yet. This will be interesting.
4-19-10 update: 4152 hrs. The GS dropped a little. it is now at %72 of initial intensity. It is in danger of dropping out of the test soon.
5-18-10 update: Nichia GS: Output has dropped to below 70%. It lasted 4,800 hrs at 30ma. At 15ma, I'd expect life to be at least 20,000 hr. Test completed.
Radio Shack 276-0017 neutral white 30 Deg LED. After 3000hrs at 30ma, there has been a small decline, however it is still at 102% of it's initial brightness. When a decline starts after thousands of hours of steady state output, means it has began its decent into the valley of the dim LED. It is too early to estimate when it will drop to below 70%.
3-18-10 update: 3384hrs. The RS LED also seems to have stabilized (slight brightness increase).
4-19-10 update: 4152hrs. Not much change. Steady as she goes!
5-18-10 update: 4848hrs. This LED shows no quit. Steady state.
6-18-10 update: 5592hrs. Slight drop but still above initial intensity.
8-19-10 : 7080hrs. No change from last measurement.
10-10-10: 8328hrs. No change. LED has been in overdrive for almost one year now. At half current, life is at least 4x, so it would last at least 4 years at 15ma. Since the LED has spent the last 4 months at steady state, I'd venture to guess that it will last 50K hours at normal drive currents.
10-26-11: 17472hrs. LED remains above initial brightness after 2 years. At this point I consider the test over.
Cree 503C-WAS-CBADA151 This part no. specifies a wide brightness and tint, but they all have been about the same brightness and tint (sample of 110 pcs). After 2000hrs, it has been a roller coaster ride of luminance, but at least it has not started to decline. The blue line is an older Cree LED. The newer 503 series is brighter and longer lasting.
3-18-10 update: 2328 hrs. The Cree just wants to get brighter. Interesting.
4-19-10 update: 3096 hrs. Notable drop, but it is back at initial output. Not sure if it is fading or just a momentary dimming. Odd how the LEDs vary over their life. I have seen this oddity in other tests not performed by me.
5-18-10 update: 3792 hrs. Trend seems to show it is now on the decline but still at 92% of initial intensity.
6-18-10 update: 4536 hrs. Falling fast and now at 70.5% of initial output. It is safe to say this LED will drop below 70% in the next couple of days. Interesting fade characteristic as compared to the GS. The GS started loosing intensity just before 1,500 hrs and slowly declined. This Cree gained intensity which peaked around 2500 hours and then started fading at a higher rate.
6-22-10 update: 4632 hrs. As expected, the LED has fallen into the 69% range. The reason for fading seems to be the discoloring (slight darkening) of the epoxy and/or the phosphors above the die. I doubt the die itself lost output. At 15ma, I'd expect the LED to last at least 20K hrs. Like the GS, this is excellent life for a 5mm LED. Test completed.
jtr1962 was kind enough to send me some surface mount LEDs for testing. These are tiny, but with masking tape, they are fairly easy to solder onto a perf board (the kind with the ring of copper around the hole).
The Osram LW E6SG PLCC4 (on Left in above photo) has been cooking at 39ma for 1680hrs and has been pretty much steady state. These have a nice near neutral white tint.
3-18-10 update: 2088 hrs. Very slow but steady decline
4-19-10 update: 2855 hrs. Now steady state. For 39ma, this LED has held up well.
5-18-10 update: 3551 hrs. Remains steady state. Amazing LED to handle 39ma so well.
6-18-10 update: 4295 hrs. Seems to be starting to descend.
8-19-10: 5783hrs slight gain in output. So, after falling a bit, it has stabilized.
10-10-10: 7031hrs. Slight drop. Still at 86% initial intensity.
10-26-11: 16175hrs. LED fell to 80% of initial brightness. At 39ma for nearly 2 years and well above 70% of initial brightness, the LED is made for the long haul. At this point, I consider the test over.
The smaller Nichia (not charted yet) is just a bit less bright and cool white. It is testing at 30ma and after nearly 600hrs has not changed
3-18-10 update: 984 hrs. Now added on chart. starting to decline.
4-19-10 update: 1752 hrs. After starting to drop, it has regained steady state output.
5-18-10 update: 2448 hrs. Starting to decline. Now at 80% intensity.
6-18-10 update: 3192 hrs. Dropped below 70% of initial intensity. Not bad for such a tiny LED. Test completed.
This is a reminder of how pathetic those cheap ebay/Chinese LEDs are. This one fell below 70% in about 3 whole days at 30ma
I decided to make it easier on the cheapo ebay LEDs. I tested them at 12.5 ma. They lasted about 500 hrs. Hey! that is 3 weeks of use!
I point out this junk because they end up in many products from cheap flashlights, to "shower head" PAR styles lights, landscape lighting and under cabinet lights. A new Menards store opened nearby and some LED lights on display were faded in 1 month!
Coming up: I have some Fox Group 360nm UV LEDs on the way and I started testing some Cree low dome 5mm 110 Deg LEDs.
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