first i want to say that yes i did read the thread about heat and the l4 i searched first /ubbthreads/images/graemlins/smile.gif. ok the talk of the 500 hr runtime on the 5w luxeon leds peaked my interest since i just aquired a l4. where does this information come from and how old is this information? i searched google about led life and even surefire led life etc etc. i cannot find any info that is not hear say and what info i do find is about a year old. do the newer leds have a greater life expectancy? when i understand that 500hrs when used infrequently amounts to quite a long time but it still seems like a serious deficiency. any info or links would be greatly appreciated. thank you /ubbthreads/images/graemlins/au.gif
L4 led question
- Thread starter rackness
- Start date
Surefire has a "forever" guarentee.
Their regular lamps last about 30 hours and cost about $20 each.
500 hours sounds like a vast improvement over incandescent to me.
In other words, I don't worry about something that may never be an issue. And if it becomes an issue, the warranty covers it.
Their regular lamps last about 30 hours and cost about $20 each.
500 hours sounds like a vast improvement over incandescent to me.
In other words, I don't worry about something that may never be an issue. And if it becomes an issue, the warranty covers it.
turbodog
Flashaholic
[ QUOTE ]
Sean said:
Surefire has a "forever" guarentee.
Their regular lamps last about 30 hours and cost about $20 each.
500 hours sounds like a vast improvement over incandescent to me.
In other words, I don't worry about something that may never be an issue. And if it becomes an issue, the warranty covers it.
[/ QUOTE ]
Exactly.
If a regular lamp is rated at 50 hours and costs $25, then that's $250 for 500 hours of running, or $.50/hour.
If the l4 head runs 500 hours and costs $100, then that's $.20/hour.
Moreover, compare an l4 to an e2e. Both put out about the same amout of light, but the l4 runs 25% longer on a set of batteries. Going back to 500 hours again. An e2e will eat 500 sets of batteries or 1000 cells in this time. That's $1000 at $1/cell. An l4 will only use 800 cells or $800 worth. If you run an l4 on pila cells, the battery costs drop to $100. $100 will get you 2 pila cells and a charger. The cells are good for a few hundred cycles each, or about 500 between the set.
Think about how long 500 hours is actually. That's 20 days straight running. And the l4 still works after this time, it's just supposed to have gotten some dimmer.
Sean said:
Surefire has a "forever" guarentee.
Their regular lamps last about 30 hours and cost about $20 each.
500 hours sounds like a vast improvement over incandescent to me.
In other words, I don't worry about something that may never be an issue. And if it becomes an issue, the warranty covers it.
[/ QUOTE ]
Exactly.
If a regular lamp is rated at 50 hours and costs $25, then that's $250 for 500 hours of running, or $.50/hour.
If the l4 head runs 500 hours and costs $100, then that's $.20/hour.
Moreover, compare an l4 to an e2e. Both put out about the same amout of light, but the l4 runs 25% longer on a set of batteries. Going back to 500 hours again. An e2e will eat 500 sets of batteries or 1000 cells in this time. That's $1000 at $1/cell. An l4 will only use 800 cells or $800 worth. If you run an l4 on pila cells, the battery costs drop to $100. $100 will get you 2 pila cells and a charger. The cells are good for a few hundred cycles each, or about 500 between the set.
Think about how long 500 hours is actually. That's 20 days straight running. And the l4 still works after this time, it's just supposed to have gotten some dimmer.
The_LED_Museum
*Retired*
LEDs don't just go "poof!" and go out like incandescents.
I believe that 500 hour value is actual run time to 50% intensity.
After 500 hours, it will still be working, but at below 50% of its "like new" intensity.
I believe that 500 hour value is actual run time to 50% intensity.
After 500 hours, it will still be working, but at below 50% of its "like new" intensity.
Since no one has answered your question...
The 500 hour figure comes direct from the manufacturer of the LED, Lumileds. The datasheet for the Luxeon V White (Called the Luxeon V Portable) states a 500 hour life to 70% brightness. According to the datasheet, 500 hours to 70% brightness occurrs when the slug temperature (the part of the LED that is thermally bonded to the flashlight body) of the Luxeon is at about 75C, which is 167F. It is highly unlikely that the L4 gets that hot during use.
If the L4 is used intermittently (only a few minutes at a time), then it can be assumed that the body temperature is, on average, relatively low. Lumileds also states that if the slug temp is maintained at 35C, then the brightness at 500 hours is 90%. Thus, we can likely conclude that with intermittent use, the Luxeon in the L4 is likely to last over 1500 hours before output is reduced to 70% of initial brightness.
The 500 hour figure comes direct from the manufacturer of the LED, Lumileds. The datasheet for the Luxeon V White (Called the Luxeon V Portable) states a 500 hour life to 70% brightness. According to the datasheet, 500 hours to 70% brightness occurrs when the slug temperature (the part of the LED that is thermally bonded to the flashlight body) of the Luxeon is at about 75C, which is 167F. It is highly unlikely that the L4 gets that hot during use.
If the L4 is used intermittently (only a few minutes at a time), then it can be assumed that the body temperature is, on average, relatively low. Lumileds also states that if the slug temp is maintained at 35C, then the brightness at 500 hours is 90%. Thus, we can likely conclude that with intermittent use, the Luxeon in the L4 is likely to last over 1500 hours before output is reduced to 70% of initial brightness.
brightnorm
Flashaholic
- Joined
- Oct 13, 2001
- Messages
- 9,027
That's reassuring and just shows the importance of data checking. I assumed it was 500hrs to 50% and underestimated the advantage of life preserving cool running.
More reason to get the Mc2S.
Brightnorm
More reason to get the Mc2S.
Brightnorm
thank you evan that is the type of answer i was looking for. i will check out the lumileds site /ubbthreads/images/graemlins/thanks.gif 500 hrs seemed like a figure if you were to leave the led on for 500 hrs straight not under normal use. good explination.
Roy
Farewell our Curmudgeon Administrator
Slightly off topic....anyone know what thte shut-down temp is for 123 Li batteries? If the batteries shut down before 75c, then I wouldn't worry too much about the 500 hours.
Steelwolf
Flashlight Enthusiast
My L4 does get uncomfortably warm during extended runs, but that doesn't suggest much since the threshold temperature may be set higher than my comfort zone. But I have yet to read any literature suggesting that there is a temperature-based throttle. It does add another degree of complexity to the circuit, which would already have been pared down to bare minimum to fit in that small head. Besides which there may be no reason for it since the L4 is only set to run at 617mA, which is short of the 750mA rated nominal input.
bhds
Enlightened
turbodog
Flashaholic
[ QUOTE ]
evan9162 said:
Since no one has answered your question...
The 500 hour figure comes direct from the manufacturer of the LED, Lumileds. The datasheet for the Luxeon V White (Called the Luxeon V Portable) states a 500 hour life to 70% brightness. According to the datasheet, 500 hours to 70% brightness occurrs when the slug temperature (the part of the LED that is thermally bonded to the flashlight body) of the Luxeon is at about 75C, which is 167F. It is highly unlikely that the L4 gets that hot during use.
If the L4 is used intermittently (only a few minutes at a time), then it can be assumed that the body temperature is, on average, relatively low. Lumileds also states that if the slug temp is maintained at 35C, then the brightness at 500 hours is 90%. Thus, we can likely conclude that with intermittent use, the Luxeon in the L4 is likely to last over 1500 hours before output is reduced to 70% of initial brightness.
[/ QUOTE ]
Since you got your question half answered and half guessed-at... /ubbthreads/images/graemlins/poke2.gif
I have spoken with people who have tested an l4 and found the slug temp to be about 15F OVER spec.
Expect lumen degradation? Yes
Expect it to still take a loooooong time? Yes
Should ANYONE care? No
If you're running your l4 on primary cells and talking about lumen degradation, you're being penny wise and pound foolish. You should be using pila cells and not caring about anything else beyond that.
evan9162 said:
Since no one has answered your question...
The 500 hour figure comes direct from the manufacturer of the LED, Lumileds. The datasheet for the Luxeon V White (Called the Luxeon V Portable) states a 500 hour life to 70% brightness. According to the datasheet, 500 hours to 70% brightness occurrs when the slug temperature (the part of the LED that is thermally bonded to the flashlight body) of the Luxeon is at about 75C, which is 167F. It is highly unlikely that the L4 gets that hot during use.
If the L4 is used intermittently (only a few minutes at a time), then it can be assumed that the body temperature is, on average, relatively low. Lumileds also states that if the slug temp is maintained at 35C, then the brightness at 500 hours is 90%. Thus, we can likely conclude that with intermittent use, the Luxeon in the L4 is likely to last over 1500 hours before output is reduced to 70% of initial brightness.
[/ QUOTE ]
Since you got your question half answered and half guessed-at... /ubbthreads/images/graemlins/poke2.gif
I have spoken with people who have tested an l4 and found the slug temp to be about 15F OVER spec.
Expect lumen degradation? Yes
Expect it to still take a loooooong time? Yes
Should ANYONE care? No
If you're running your l4 on primary cells and talking about lumen degradation, you're being penny wise and pound foolish. You should be using pila cells and not caring about anything else beyond that.
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