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  1.    #1  
    While it sure makes a handy bright flashlight, I'm concerned about possible damage to the LED.

    I work with high-power LEDs and they make a good amount of heat that requires proper thermal management for continuous full-power operation. Heat is a big enemy for LEDs and will not necessarialy cause them to burn out, but will cause them to lose brightness. LED life is rated in hours until it reaches a predetermined percentage of the original brightness, running at the rated power, and with the proper thermal considerations... burning out completely is possible though if the LED is run outside of it's ratings.

    All that said, a phone camera flash LED is almost certainly not designed for continuous operation and using it as a flashlight will undoubtedly take a toll on it's lifespan and subsequntly, it's brightness.

    I'm going to stick with my Photon Micro-Light on my keychain.
  2. #2  
    I'm not sure this is any amount of heat that can be felt, but i've had mine on for a good 15minutes and turned off/on for further use after that during night while working in my car. Never had any issues here.

    :-/
  3. #3  
    Quote Originally Posted by DrHeathenScum View Post
    ...
    All that said, a phone camera flash LED is almost certainly not designed for continuous operation and using it as a flashlight will undoubtedly take a toll on it's lifespan and subsequntly, it's brightness.
    ...
    How can you be certain of this? Do you have any research or specifications that back this up?
  4. #4  
    Quote Originally Posted by DrHeathenScum View Post
    While it sure makes a handy bright flashlight, I'm concerned about possible damage to the LED.

    I work with high-power LEDs and they make a good amount of heat that requires proper thermal management for continuous full-power operation. Heat is a big enemy for LEDs and will not necessarialy cause them to burn out, but will cause them to lose brightness. LED life is rated in hours until it reaches a predetermined percentage of the original brightness, running at the rated power, and with the proper thermal considerations... burning out completely is possible though if the LED is run outside of it's ratings.

    All that said, a phone camera flash LED is almost certainly not designed for continuous operation and using it as a flashlight will undoubtedly take a toll on it's lifespan and subsequntly, it's brightness.

    I'm going to stick with my Photon Micro-Light on my keychain.
    Everything you said is certainly true. Even the 3W Cree LED in one of my flashlights gets pretty hot. But that LED puts out close to 200 lumens and runs on CR123A lithium primary cells. Point is, the flash led is so weak that it probably produces very little heat, and even then, it's probably rated to tens of thousands of hours, just like any typical LED. I wouldn't use it for a search and rescue operation, but for a quick light, I doubt it would cause any damage.
  5. Thead's Avatar
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    #5  
    My light probably gets around 30-45 minutes of use a week from walking outside at night. My assumption is that while it may reduce the life of the LED, I will have upgraded to a new phone loooong before that will ever happen.
  6. #6  
    I thought LED's (light emiting diodes, is this correct?) are NOT supposed to give out heat??!!??!!
  7.    #7  
    I can't provide any proof of the camera flash LED not being designed for continuous usage, but why would it be, it's a camera *flash*. From my knowledge, camera flash LEDs are not designed with large thermal pads and are usually assembled on boards the lack thermal management considerations that a continous-use LED assembly would have. Again, it is a flash LED, only to be pulsed every so often, making heat not much of an issue.

    You probably wouldn't feel the heat from it as it would be small in relation to a flashlight LED.
  8.    #8  
    BTW, the overwhelming lack of knowledge regarding LEDs and their operation, brought on mostly by unsavory advertising/promotion of LED products, never ceases to amaze me.
  9. #9  
    Quote Originally Posted by sputnik767 View Post
    Everything you said is certainly true. Even the 3W Cree LED in one of my flashlights gets pretty hot. But that LED puts out close to 200 lumens and runs on CR123A lithium primary cells. Point is, the flash led is so weak that it probably produces very little heat, and even then, it's probably rated to tens of thousands of hours, just like any typical LED. I wouldn't use it for a search and rescue operation, but for a quick light, I doubt it would cause any damage.
    Keep in mind that the reason your 3w Cree LED flashlight gets hot is because the emitter is being overdriven like crazy (I bet).
  10.    #10  
    Quote Originally Posted by rogerkang View Post
    Keep in mind that the reason your 3w Cree LED flashlight gets hot is because the emitter is being overdriven like crazy (I bet).
    A 3W LED, being driven within spec, makes a good amount of heat... you would be surprised.
  11. #11  
    I would also like to side with the white LEDs do not provide enough heat to create sufficient problems. From my own personal use of different colors and specifications, have noticed no direct problems with heat, as long as they are used properly, especially compared to that of a normal resister.

    Additionally I don't believe there are people who specifically run the LED for enough time to create sufficient heat to cause damage, especially on a device with much more energy consuming and heat producing components such as a 3g radio, cpu, and gpu.
  12. #12  
    Quote Originally Posted by ColbyM View Post
    I thought LED's (light emiting diodes, is this correct?) are NOT supposed to give out heat??!!??!!
    They can give out quite a bit of heat actually, although not nearly as much as a comparable halogen bulb. The 200 lumen halogen bulb in my SureFire flashlight will get so hot, that after 20 mins it becomes difficult to hold it. But I am talking about the good led lights, not the cheap wal mart brands that run off alkaline batteries. The cheap ones may not put out any noticeable heat.
  13.    #13  
    Also, the heat I am referring to is heat in the semiconductor junction of the LED.... without a thermal path, it stays in the junction, overheating it with little outward signs.
  14. #14  
    I think all of these topics and opinions are good to a point. Until someone pulls the specifications of the light bulb being used or ask someone from Palm, these points all seem moot. That is like saying the NoDoze app will affect your screen drastically because the screen was not designed to always be on. I have no information to back that up so, for now, it is all conjecture.
  15. #15  
    Yes, I am aware of how much heat it generates. But if properly heat-sinked with good thermal pathways to the flashlight body, you won't notice it much *if you are holding the light* and not leaving it alone on a table, etc. where it can get hot on its own.

    Your body does a surprisingly good job of keeping the flashlight temp down (when you are holding the light in your hand).

    For a 3W LED to be driven at 3W, you're talking roughly 3.2v - 3.3v (for the latest Cree XP-G emitter, for example) x around 920mA of current. That's pretty high, although I admit it's not overdriving the LED like some lights.

    Yes, I am assuming that the above poster does not have the most efficient light but more of a "brightness counts" light. It seems like so many lights made today emphasize brightness and NOT efficiency of the LED (like driving it at 350 or 500mA for optimal efficiency).

    For the camera flash LED, we are talking an emitter that is being driven at 50mA - 200mA, depending on which setting you use. (I am assuming the use of Jason's flashlight torch app.)
    I doubt the emitter is spec'd out to be driven below this. Short use should be OK. But then again, I'm not sure if flash LEDs used in cameras these days come with shorter lives than other LEDs. Probably not too significant. I mean, if you decrease the life of the flash LED from 10,000 hours to 1,000 hours, what's the big deal? Most people will never use their flashlight for 1,000 hours, etc. Most Pre users will be on to their next WebOS phone by the time the LED starts to dim noticeably.
  16. #16  
    Quote Originally Posted by sputnik767 View Post
    They can give out quite a bit of heat actually, although not nearly as much as a comparable halogen bulb. The 200 lumen halogen bulb in my SureFire flashlight will get so hot, that after 20 mins it becomes difficult to hold it. But I am talking about the good led lights, not the cheap wal mart brands that run off alkaline batteries. The cheap ones may not put out any noticeable heat.
    I've seen high-end LED lights (overdriven) get so hot that they burned through the pocket in a pair of shorts! (I think the material was synthetic--not cotton.)
  17.    #17  
    Well, other than speculation and educated guesses, the only way to really know the bottom line is the find out the type of LED and associated specifications that is used in the Pre/Pixi, and to also find out what the current it is being driven at is, and also what, if any, thermal management is employed inside the phone.

    In the meantime, I am not using my camera flash for a flashlight.
  18. #18  
    Quote Originally Posted by DrHeathenScum View Post
    While it sure makes a handy bright flashlight, I'm concerned about possible damage to the LED.

    I work with high-power LEDs and they make a good amount of heat that requires proper thermal management for continuous full-power operation. Heat is a big enemy for LEDs and will not necessarialy cause them to burn out, but will cause them to lose brightness. LED life is rated in hours until it reaches a predetermined percentage of the original brightness, running at the rated power, and with the proper thermal considerations... burning out completely is possible though if the LED is run outside of it's ratings.

    All that said, a phone camera flash LED is almost certainly not designed for continuous operation and using it as a flashlight will undoubtedly take a toll on it's lifespan and subsequntly, it's brightness.

    I'm going to stick with my Photon Micro-Light on my keychain.
    love my flashlight patch,if anything goes wrong,take it back and do it all over again. Thanks for the heads up though. ;-)
  19. blu8503's Avatar
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    #19  
    Quote Originally Posted by DrHeathenScum View Post
    Well, other than speculation and educated guesses, the only way to really know the bottom line is the find out the type of LED and associated specifications that is used in the Pre/Pixi, and to also find out what the current it is being driven at is, and also what, if any, thermal management is employed inside the phone.

    In the meantime, I am not using my camera flash for a flashlight.
    c'mon you said it yourself this is speculation. LED's last a really freakin long time!! The heat put out is very very minimal in this situation. If we were talking about a flash on a full sized camera I may worry but man this is a phone you will have for like two years maybe three but I doubt it. That little LED will last long after my phone is gone
  20. #20  
    Quote Originally Posted by bpdamas View Post
    I think all of these topics and opinions are good to a point. Until someone pulls the specifications of the light bulb being used or ask someone from Palm, these points all seem moot. That is like saying the NoDoze app will affect your screen drastically because the screen was not designed to always be on. I have no information to back that up so, for now, it is all conjecture.
    You have a good point, but the OP is just warning people that the use of the flash LED as a flashlight (outside of its planned purpose) may shorten its life. The Nodoze app shouldn't affect your screen drastically b/c the phone's screen is still on when people use the Touchstone to charge it. So Palm has done the proper testing and knows that the screen should hold up for X number of years even if it is on all night, etc.

    Here, we are taking an LED that was originally designed for temporary, short bursts and we turned it into a flashlight that might be on for 5, 10, 20, 90 minutes...

    Anyway, I decided to open up my phone (again) to check out the LED and see if there is any heatsink. Looks like there is a little bit of metal that can act as a heatsink. So a little bit of flashlight use here and there should be OK.

    (Yes, my Pre's innards are VERY dusty! haha)
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