# Do MC-E LED's Need a "Break/Burn In" Period?



## Jerry B (Apr 22, 2009)

I have a Tiablo ACE light with a Cree MC-E LED that supposedly puts out 700 lumens. It is an extremely bright light. 
Since I work in a store that also sells these lights , I thought,that after using the light for probably 6 hours of burn time, I'd just compare it to a brand new unit out of the box. To my surprise, my "used" light seemed considerably brighter than the brand new unit! This started to make me wonder if a LED actually improves a bit after a certain period of operation?:thinking:


----------



## csshih (Apr 22, 2009)

strange.. to my knowledge, LEDs do not have a burn in period. 

you are comparing the same lights, same batteries?


----------



## Jerry B (Apr 22, 2009)

csshih said:


> strange.. to my knowledge, LEDs do not have a burn in period.
> 
> you are comparing the same lights, same batteries?


Oh yeah, these were identical Tiablo ACE flashlights.


----------



## easilyled (Apr 22, 2009)

Sorry for asking but were you using them both on the same level?

Its possible, for example that the original one had been set to max, whereas the one out the box came on at a lower level.

Also, as csshih says, if you have differing battery configurations, that could make a difference.

For example 2 CR123s might give more output than 1 18650.


----------



## Jerry B (Apr 22, 2009)

easilyled said:


> Sorry for asking but were you using them both on the same level?
> 
> Its possible, for example that the original one had been set to max, whereas the one out the box came on at a lower level.
> 
> ...


The Tiablo ACE has one fixed output!


----------



## easilyled (Apr 22, 2009)

Jerry B said:


> The Tiablo ACE has one fixed output!



Well I guess it must be another reason then.


----------



## csshih (Apr 22, 2009)

how much would you judge "considerably" to be? 
Is it possible that you could take beamshots?

I'd think that the natural variation in dies would produce a slight change, but not enough to be noticeable.. 

hmm.. is tiablo using different Bins, also?

they state that they use M bin 
(M 430-490 lumens @ 350mAh)

hmm... 60 lumens difference @ lower currents.. I'd think the variance could be up ~100 lumens @ higher currents, which would be noticeable.. but not extremely, so the first question would be my important one.


----------



## Gunner12 (Apr 22, 2009)

There is always a slight variation of output between individual LEDs, even LEDs from the same flux bin. The Vf of the LEDs can also make a difference. The difference in tint(even between LEDs of the same tint bin) can also make one LED seem brighter then another.

One of the lights might have a LED towards the higher end of the flux bin while the other one could have one from the lower end. The brighter one could also have a bluer tint which would seem brighter and also a lower Vf (which could mean a bit more current to the LED).


----------



## TexLite (Apr 23, 2009)

As has been mentioned, the differential in the flux bins could account for some variation in brightness.

Also, some LED's do exhibit a "burn in" of sorts, meaning the Vf will drop over the first hours of operation. I'm not sure if this affects the MC-E. 

-Michael


----------



## tebore (Apr 23, 2009)

TexLite said:


> As has been mentioned, the differential in the flux bins could account for some variation in brightness.
> 
> Also, some LED's do exhibit a "burn in" of sorts, meaning the Vf will drop over the first hours of operation. I'm not sure if this affects the MC-E.
> 
> -Michael



You're right. If we can factor out bin variations, all LEDs exhibit a vf shift after a few to a few thousand hours of operation. It can shift a whole bin in this time period.


----------



## TexLite (Apr 24, 2009)

tebore said:


> You're right. If we can factor out bin variations, all LEDs exhibit a vf shift after a few to a few thousand hours of operation. It can shift a whole bin in this time period.



Yes thats right. And depending on the type of driver, it could account for a modest change in brightness. Might not be noticeable alone, but side by side it could be.

I haven't seen any data yet on the MC-E, but the effect is documented with other emitters so its reasonable to assume the MC-E is affected as well.

-Michael


----------



## GrnXnham (Apr 24, 2009)

Jerry B said:


> I have a Tiablo ACE light with a Cree MC-E LED that supposedly puts out 700 lumens. It is an extremely bright light.
> Since I work in a store that also sells these lights , I thought,that after using the light for probably 6 hours of burn time, I'd just compare it to a brand new unit out of the box. To my surprise, my "used" light seemed considerably brighter than the brand new unit! This started to make me wonder if a LED actually improves a bit after a certain period of operation?:thinking:



Burn in?

It's a flashlight not a plasma TV!


----------

