typical lamp life of Luxeon 5
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scudinc
Enlightened
The Luxeon V lasts for only a few hundred hours.
idleprocess
Flashaholic
The Luxeon V Portable is listed as being able to maintain a given lumens percentage after 500 hours under given conditions.
<font class="small">Code:</font><hr /><pre>
Average Lumen Maintenance Characteristics
Heat sink temp Drive Current Average Lumen Maintenance after 500 hours of operation
35°C 700 mA 90%
75°C 700 mA 75%
85°C 600 mA 65%
</pre><hr />
Here's the disclaimer - emphasis mine:
[ QUOTE ]
Luxeon V Portable is designed primarily for portable lighting and other applications requiring operating lifetimes of 500 hours and less. While the device will operate past 500 hours, its lumen maintenance cannot yet be characterized. Longer life versions of white Luxeon V will become available in the future.
Average lumen maintenance is dependant on heat-sink temperature. A recoverable light output loss may occur during the first 500 hours of operation.
[/ QUOTE ]
Both cites are from Lumileds' DS40.
I take the disclaimer to mean that Lumileds can't predict the phosphor degradation at 5W, since the phosphor is typically the first thing to go in a blue LED+yellow phorsphor white LED. 5W is a lot of heat for such a small package.
There are also factors such as the inherent problems associated with parallel designs - one die might shift Vf unpredictably, resulting in a big increase in current through one string that kills it (Vf drops), or the other (Vf jumps).
There are plenty of folks out there that have extracted thousands of hours of use from the LuxV Portable without noticable loss of output. Some say the performance degradation curve on the LuxV Portable is similar to the Luxeon III.
<font class="small">Code:</font><hr /><pre>
Average Lumen Maintenance Characteristics
Heat sink temp Drive Current Average Lumen Maintenance after 500 hours of operation
35°C 700 mA 90%
75°C 700 mA 75%
85°C 600 mA 65%
</pre><hr />
Here's the disclaimer - emphasis mine:
[ QUOTE ]
Luxeon V Portable is designed primarily for portable lighting and other applications requiring operating lifetimes of 500 hours and less. While the device will operate past 500 hours, its lumen maintenance cannot yet be characterized. Longer life versions of white Luxeon V will become available in the future.
Average lumen maintenance is dependant on heat-sink temperature. A recoverable light output loss may occur during the first 500 hours of operation.
[/ QUOTE ]
Both cites are from Lumileds' DS40.
I take the disclaimer to mean that Lumileds can't predict the phosphor degradation at 5W, since the phosphor is typically the first thing to go in a blue LED+yellow phorsphor white LED. 5W is a lot of heat for such a small package.
There are also factors such as the inherent problems associated with parallel designs - one die might shift Vf unpredictably, resulting in a big increase in current through one string that kills it (Vf drops), or the other (Vf jumps).
There are plenty of folks out there that have extracted thousands of hours of use from the LuxV Portable without noticable loss of output. Some say the performance degradation curve on the LuxV Portable is similar to the Luxeon III.
BentHeadTX
Flashlight Enthusiast
I just built a nFlex WX1S LuxeonV Mag with a big heat sink. The sheer mass of the 2D Mag keeps the LED very, very cool (Kudos to Artic Silver thermal epoxy and hotlips heat sinks) Here is something to chew on, a basic question concerning power draw.
My WX1S is very low voltage with a tested forward voltage of 6.15 volts at 700mA. That would equal 4.3 watts. Then factor in a vF drop of around .3 to .4V after about 50 hours of use, my wattage will be around 4.1 to 4.2 watts. 95% of the time the light is dimmed down to less than 1.5 watts so will I get increased life expectancy?
A Luxeon III will last 20,000 hours at 1,000mA or around 4 watts. Can I expect 10,000 hours or more due to lower wattage and much less heat due to heat sinking? Just something to chew on.
In reality, I am waiting for a LuxeonIII with a XWAH, it will be a few years so the life is not too big of a concern. Is the LuxV's downfall the heat or the phosporus?
My WX1S is very low voltage with a tested forward voltage of 6.15 volts at 700mA. That would equal 4.3 watts. Then factor in a vF drop of around .3 to .4V after about 50 hours of use, my wattage will be around 4.1 to 4.2 watts. 95% of the time the light is dimmed down to less than 1.5 watts so will I get increased life expectancy?
A Luxeon III will last 20,000 hours at 1,000mA or around 4 watts. Can I expect 10,000 hours or more due to lower wattage and much less heat due to heat sinking? Just something to chew on.
In reality, I am waiting for a LuxeonIII with a XWAH, it will be a few years so the life is not too big of a concern. Is the LuxV's downfall the heat or the phosporus?
[ QUOTE ]
95% of the time the light is dimmed down to less than 1.5 watts so will I get increased life expectancy?
[/ QUOTE ]
Most definitely. 1.5W would be something like 250mA. I'd expect the Lux V to easily exceed 100K hours of life at that power level.
[ QUOTE ]
Can I expect 10,000 hours or more due to lower wattage and much less heat due to heat sinking?
[/ QUOTE ]
Yes easily on the lower wattage. As for the heatsinking, if you're talking about at nominal power (700mA), then maybe - possibly into the 1000s of hours.
[ QUOTE ]
Is the LuxV's downfall the heat or the phosporus?
[/ QUOTE ]
It's easily phosphor degridation due to heat. The green/blue Luxeon Vs have the expected lifetime of 50K hours like all other parts. I've hypothesized that the phosphor is cooked at lot more on a Luxeon V than in other devices.
95% of the time the light is dimmed down to less than 1.5 watts so will I get increased life expectancy?
[/ QUOTE ]
Most definitely. 1.5W would be something like 250mA. I'd expect the Lux V to easily exceed 100K hours of life at that power level.
[ QUOTE ]
Can I expect 10,000 hours or more due to lower wattage and much less heat due to heat sinking?
[/ QUOTE ]
Yes easily on the lower wattage. As for the heatsinking, if you're talking about at nominal power (700mA), then maybe - possibly into the 1000s of hours.
[ QUOTE ]
Is the LuxV's downfall the heat or the phosporus?
[/ QUOTE ]
It's easily phosphor degridation due to heat. The green/blue Luxeon Vs have the expected lifetime of 50K hours like all other parts. I've hypothesized that the phosphor is cooked at lot more on a Luxeon V than in other devices.
NewBie
*Retired*
[ QUOTE ]
evan9162 said:
[ QUOTE ]
95% of the time the light is dimmed down to less than 1.5 watts so will I get increased life expectancy?
[/ QUOTE ]
Most definitely. 1.5W would be something like 250mA. I'd expect the Lux V to easily exceed 100K hours of life at that power level.
[ QUOTE ]
Can I expect 10,000 hours or more due to lower wattage and much less heat due to heat sinking?
[/ QUOTE ]
Yes easily on the lower wattage. As for the heatsinking, if you're talking about at nominal power (700mA), then maybe - possibly into the 1000s of hours.
[ QUOTE ]
Is the LuxV's downfall the heat or the phosporus?
[/ QUOTE ]
It's easily phosphor degridation due to heat. The green/blue Luxeon Vs have the expected lifetime of 50K hours like all other parts. I've hypothesized that the phosphor is cooked at lot more on a Luxeon V than in other devices.
[/ QUOTE ]
Of course you probably remember this evan9162, but for the benefit of others...
It is not at all, whatsoever, that they don't know yet or any silly thought like that.
Years ago, LumiLEDs released this part. Even though customers were abiding by all the design critera that LumiLEDs gave them, LumiLEDs denied it for a short period of time. After complaints from a multitude of respected folks in the industry showed LumiLEDs they were wrong and these Luxeon V devices actually had a problem.
The datasheet was quicky revised.
LumiLEDs engineers that visited me said they had a number of fixes already in testing. This was quite some time ago.
Had LumiLEDs actually fixed the devices, I'd be quite surprised if they didn't fix their datasheet. It would only take 42 days to determine if the changes helped for certain. By 84 days, you'd know if you'd extended the lifetime of the part to 1000 hours. So I don't buy the, "they can't tell yet line...", as this part is years old.
They know, and its been tested very specifically, so they are giving you hours of life very specifically, under very specific conditions.
If affected only a portion of the population, they might even give a statistical distribution for typical parts. They didn't.
Also keep in mind, many of us cpf'ers put very robust heatsinks on huge D cell Maglites, and used quite substantial heatsinks, hotlips was a common design. It would be interesting to put thermalcouples on one of these while in the flashlight.
Keep in mind that when overdriving these LEDs, the life does not decrease at a porportional linear curve, but follows a dramatic exponential curve. Overdriving brings on loss of light much faster.
Also your eyes are not linear, but logarithmic, and if you weren't doing side by side comparisions, it would be doubtful you'd notice.
One point I do recall, folks kept thinking Gransee had improved their ARC AAA design, as it was so much brighter than their old one they have. No changes, just their LED had degraded, and they didn't realize it. The ARC AA and AAA over drove it's LED by quite alot, so they degraded rather fast.
evan9162 said:
[ QUOTE ]
95% of the time the light is dimmed down to less than 1.5 watts so will I get increased life expectancy?
[/ QUOTE ]
Most definitely. 1.5W would be something like 250mA. I'd expect the Lux V to easily exceed 100K hours of life at that power level.
[ QUOTE ]
Can I expect 10,000 hours or more due to lower wattage and much less heat due to heat sinking?
[/ QUOTE ]
Yes easily on the lower wattage. As for the heatsinking, if you're talking about at nominal power (700mA), then maybe - possibly into the 1000s of hours.
[ QUOTE ]
Is the LuxV's downfall the heat or the phosporus?
[/ QUOTE ]
It's easily phosphor degridation due to heat. The green/blue Luxeon Vs have the expected lifetime of 50K hours like all other parts. I've hypothesized that the phosphor is cooked at lot more on a Luxeon V than in other devices.
[/ QUOTE ]
Of course you probably remember this evan9162, but for the benefit of others...
It is not at all, whatsoever, that they don't know yet or any silly thought like that.
Years ago, LumiLEDs released this part. Even though customers were abiding by all the design critera that LumiLEDs gave them, LumiLEDs denied it for a short period of time. After complaints from a multitude of respected folks in the industry showed LumiLEDs they were wrong and these Luxeon V devices actually had a problem.
The datasheet was quicky revised.
LumiLEDs engineers that visited me said they had a number of fixes already in testing. This was quite some time ago.
Had LumiLEDs actually fixed the devices, I'd be quite surprised if they didn't fix their datasheet. It would only take 42 days to determine if the changes helped for certain. By 84 days, you'd know if you'd extended the lifetime of the part to 1000 hours. So I don't buy the, "they can't tell yet line...", as this part is years old.
They know, and its been tested very specifically, so they are giving you hours of life very specifically, under very specific conditions.
If affected only a portion of the population, they might even give a statistical distribution for typical parts. They didn't.
Also keep in mind, many of us cpf'ers put very robust heatsinks on huge D cell Maglites, and used quite substantial heatsinks, hotlips was a common design. It would be interesting to put thermalcouples on one of these while in the flashlight.
Keep in mind that when overdriving these LEDs, the life does not decrease at a porportional linear curve, but follows a dramatic exponential curve. Overdriving brings on loss of light much faster.
Also your eyes are not linear, but logarithmic, and if you weren't doing side by side comparisions, it would be doubtful you'd notice.
One point I do recall, folks kept thinking Gransee had improved their ARC AAA design, as it was so much brighter than their old one they have. No changes, just their LED had degraded, and they didn't realize it. The ARC AA and AAA over drove it's LED by quite alot, so they degraded rather fast.
