Driving the diod Turbo.

nirrebosse

Newly Enlightened
Joined
Oct 17, 2011
Messages
15
Hello.
Sorry if I ask something you diskussed before but I have read and cant realy find the answer I looking for.
And I,m also curios how you with extended experience use the lightlevels on your Flashlights.


I have a Fenix LD10. The diod is a XP-G R5.

It has lightlevels on 9, 50, 105 and 132 lumens. The lowest is perfect for descret lightning indoors or to be visible outdoors for ex on a bike, but Its not very bright when for ex going out to a moosepost before dawn. Even if I find level 2 at 50 lumens good, and much better than I,m used to with my princton tec Impact, or mini mag, I,m drawn to more light. 105 lumen, level three is three klicks away and its easyer to just twist between the levels 9 and 132. I have recargable eneloops at 2500 and GP at 2700 and they bouth provide with broad range more than 1.5 hours runtime on the Turbolevel. I also carry 2 spare Battery in my backpack in a watertight Fenix carryer made for the headlamp application.

I,m curious what happens to the diod with long running times. Will it have a shorter lifetime than the estated 50.000 hours or vill it loose its maximum capasity quick due to temperatures?
I,ve run it for 1/2 hours at a time on turbo already so the diod is not melting anyway by being far to hot.

By the way if the flashlight shines good for me even 5.000 hours its good enough as that will represent at least ten years of use and I will happily by a new one. I think a lot of things beside the diod is the things that decide the lifespan of a tecnical thing as a flashlight.

Give me some thoughts about my light and how to use it wisely and tell a little about witch lightlevels you like and why?

Bosse
 

Jash

Flashlight Enthusiast
Joined
Nov 4, 2009
Messages
1,649
Location
Brisbane, Queensland, Australia
My advice would be to get another light where the mid range is the output you're after. You'll have to got to at least a 2AA light which ups the size a bit, but you'll be happier with the longer runtimes and the option of an even higher output turbo mode.

I like my big lights for outdoor use and regularly use upwards of 400 lumens for extended periods. There's no such thing as too bright of you want to see things in the distance at night, especially if your safety depends on it.
 

nirrebosse

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Joined
Oct 17, 2011
Messages
15
A good thing with a bigger lightthrower is the higher Turbo mode and I could probobly use also that all the time because much light is good for most of my uses.
But that LD10 in small 1 X AA is good enough, very light to carry in a pack or pocket, or on the headband and it takes almost no space so its the perfect EDC size. + 1,5 h with extra bateries in my pack or more than 30 hours on 9 lumens is good enough for me and my uses.

Ive seen that R5 diod deliver 277 lumen in a Fenix HP 11 headlamp driven by 4 X AA. This would make my flashlight safe to use at Turbo. It must have been the powersource of 1 X AA rather than maximum uttake from the Diod that have set the limit for the light in the turbomode?

Bosse
 

yifu

Enlightened
Joined
Oct 15, 2011
Messages
713
Location
Australia
Check out the lumen maintenance results for all current Cree LEDs here, http://www.cree.com/products/pdf/LM-80_Results.pdf
You would see that even at 105 degrees Celsius, the lumen maintenance after 6000 hours at 1A current was 97.4%, with a extrapolated L70 lifespan of over 36 000 hours, only suffering a chromaticity shift of 0.0032. What this means is that as long as the light is not too hot to hold, it would be just fine. With good lights with good thermal design, LED temperature should quickly transfer to the body, meaning that if you can hold it, its DEFINITELY below 105 degrees (i definitely cant touch stuff hotter than boiling water) and no damage will occur. Feel free to use it on turbo.
 

nirrebosse

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Joined
Oct 17, 2011
Messages
15
yifu. interesting answer.
I have only been here some weeks so some of what you write im not cerain how to understand but I will learn.
Do we think inner temperature within the lighthouse or is it the outertemperature outside the lamphouse. Here we starting the season with minus deegres celsius and snow so the climate is rather cooling so is the wind using it on the bicykle.

Bosse
 

yifu

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Joined
Oct 15, 2011
Messages
713
Location
Australia
Haha i'll admit it does take a while to learn all of that stuff, i have been here way longer than my join date since this is a new account (lost the old one). BTW the 105 degrees celsius (221F) refers to the temperature the LED itself is exposed to for 6000 hours straight (the entire test took about a year to complete). During that time it has only lost 2.6% of its light output, if you apply a bit of logarithms and extrapolate it (i wont do it here unless you request), Cree estimates 36 300 hours before its light output falls below 70%(L70 lifespan) at 105 degrees. A good flashlight would have a good thermal path, so that LED heat would transfer very fast to the body of the flashlight. This means that the LED temperature will= Flashlight body temperature.
Bottom line is, dont worry about the LED dying unless you're using a modded light in a small body. The E03 for example is the same size as your LD10 but produces 6 times the amount of light if modded with a 3A driver. And even then, if you can hold the light, it's totally fine. Strangers to higher powered LED flashlights just dont know that LEDs can produce a lot of heat as well (they are only 20% efficient, so 80% input power is heat).
 
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nirrebosse

Newly Enlightened
Joined
Oct 17, 2011
Messages
15
Yifu. thanks for sharing your knowledge with me.
My Fenix havent even been warm at the outside so I continue drive it in Turbo for longer times when needed.

I starting to see a real thrill in this Flashlightinterest. Modifications, improvements and the jungle of LEDs.
Intereresting,
Pity its daylight during the day, We looses a lot of awake time in daylight ;)
All and All the sun also has its good sides.

Bosse
 
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