Fenix L2D - when your hot ... your hot

watchdog2001 · Jun 23, 2007

Fellow Fenix L2D owners,
I used my L2D today for about 30 minutes non-stop in Turbo mode and couldn't believe how hot it had gotten. Knowing that the Cree emitter is such high output, I guess I should have expected but I must say I wasn't expecting the extreme. The head area wasn't hot enough to burn but was very uncomfortable to hold.
Should I not run the L2D in turbo mode for extend periods? What is the longest time you have run your L2D in turbo mode and were you surprised by the heat generated by the emitter.

John

qip · Jun 23, 2007

i tried to drain an old set of alks and ran the l2d for 45min it did get hot but the light did not dim which was good

LukeA · Jun 23, 2007

no angry blue = okay to keep running the light, IMO.

ZMZ67 · Jun 24, 2007

Wouldn't the heat eventually damage the electronics even if the led isn't to the point of overheating? I am really asking this for led lights in general not just the L2D.Sometime back there was a test done by a member on a P1D CE and the light ended up dead.I don't seem to remember anything about the led going blue first, but I could be wrong. :thinking:

BB · Jun 24, 2007

Were you running Alkaline AA's or something else... I have found Alkaline batteries--especially when nearing depletion get very hot under load (this was with a small portable TV using 3x AA). It was very surprising.

If you look at the LxD-CE review on FlashlightReviews.com, you will see that the LxD-CE head on Turbo flattens the 1 or 2 AA configuration quite quickly--so, that would be my guess at where the heat could be coming from and changing to Ni-MH or Lithium batteries may help the light run cooler and longer @ Turbo & high settings.

-Bill

watchdog2001 · Jun 24, 2007

Actually, I am running Duracell Alkalines in it. I just purchased a few sets of Sanyo Eneloop that I have yet to put in the L2D. It might be time to give them a try and see if that makes a difference.

John

socalrunner · Jun 24, 2007

I have used the L2d in Turbo for 2 hours using duracell nimh.. It felt warm but definitely not hot.. I was using as a bike light for it may have been kept cooler by the night air..

carrot · Jun 24, 2007

All evidence thus far points to the Cree LED being a pretty robust one. I wouldn't worry about it. If something should go wrong from such usage (which is normal use), most reputable vendors' warranties should cover you.

ensile · Jun 24, 2007

switched my p2d to Strobe and sat it directly under the mirror ball at a friends party last night, it was crazy, then SOS, but that was annoying, i settled on low mode and it was a comfortable slow spinning sparkle.

BGater · Jun 24, 2007

Have you ever sniffed an Energizer Lith when its hot ? Man, its a funny smell, had my L1D running for like 20 min one night and it got very warm, opened it up to see how hot the battery was and noticed the odor. :green:

WildChild · Jun 24, 2007

I ran mine for 2h (completely depleting a NiMH set) many times. Yes it becomes quite warm but not enough hot to be uncomfortable to me to hold in in my hands.

motorcyclist · Jun 24, 2007

Will running at Turbo mode exclusively shorten the life of the LED/circuit?

WildChild · Jun 24, 2007

motorcyclist said:
Will running at Turbo mode exclusively shorten the life of the LED/circuit?

I don't really care as no warning against running the light in turbo mode all the time is given. I guess if the LED/circuit fails, it will be covered by the warranty! Enjoy your light the way you like it best. This is what I do with mine and I love it.

moon lander · Jun 24, 2007

the problem is that when the led gets overdriven it can lose output gradually. you might not notice that your led is 2% dimmer after it got hot until months later you compare it to a new one and realize you've cumulatively worn it out.

also, i think its only the seouls that turn blue when they are too hot. the crees will not give you this convenient warning that they are too hot, they just keep shining.

WildChild · Jun 24, 2007

moon lander said:
the problem is that when the led gets overdriven it can lose output gradually. you might not notice that your led is 2% dimmer after it got hot until months later you compare it to a new one and realize you've cumulatively worn it out.

also, i think its only the seouls that turn blue when they are too hot. the crees will not give you this convenient warning that they are too hot, they just keep shining.

Cree have been proven to be more resistant to heat than Seouls. Anyway, 2% after many months is nothing! And for sure, the LED in the L2D isn't overdriven. Also as I said, I'm pretty sure that if something happens during normal usage (huge dimming, strange death, "place any funny effect here"), including usage in turbo mode, it will be covered by the warranty!

zipplet · Jun 24, 2007

I think it's OK, remember the light is very well heatsinked - the fact you can feel the heat so much is proof of this and it's a Good Thing. Using alkalines, a large portion of the heat will be coming from them due to the internal resistance. I have a 1xAA mobile phone emergency charger and with an alkaline it gets very hot - with an eneloop it just gets quite warm.

Hans · Jun 24, 2007

WildChild said:
Also as I said, I'm pretty sure that if something happens during normal usage (huge dimming, strange death, "place any funny effect here"), including usage in turbo mode, it will be covered by the warranty!

Probably yes, but OTOH this won't really help you much when your light suddenly dies in the middle of nowhere. Sure, most people will carry at least one backup on longer trips, but still. I tend to be pretty careful with my lights, and when a light gets *really* hot I tend to switch to a lower level unless I *really* need all the light I can get.

BTW, in my not so humble opinion in an ideal world all LED lights would have a heat sensor that switches the light to a lower level before any damage to the LED or the circuit can occur, like the HDS. This is one of the more important features of a light because it increases its reliability, and it's getting more and more important at a time when the lights are getting more and more powerful.

Hans

wintermute · Jun 24, 2007

zipplet said:
I think it's OK, remember the light is very well heatsinked - the fact you can feel the heat so much is proof of this and it's a Good Thing. Using alkalines, a large portion of the heat will be coming from them due to the internal resistance. I have a 1xAA mobile phone emergency charger and with an alkaline it gets very hot - with an eneloop it just gets quite warm.

Exactly - hot is good. It would be much worse if you ran this thing at a high current and it didn't get hot. I have a light which uses a little aluminum "pill" which houses the electronics as well as mounts the star. Well, the only way the pill is heatsinked to the body is through a loose connection with the side. I wrapped the pill in some copper heatsink tape I obtained from another company and now the pill fits snugly into the body. Now when the light runs for an extended period of time the aluminum body of the flashlight actually gets hot - which is a good sign that it is pulling heat away from the electronics and the LED.

Cydonia · Jun 24, 2007

Hans said:
Probably yes, but OTOH this won't really help you much when your light suddenly dies in the middle of nowhere. Sure, most people will carry at least one backup on longer trips, but still. I tend to be pretty careful with my lights, and when a light gets *really* hot I tend to switch to a lower level unless I *really* need all the light I can get.

BTW, in my not so humble opinion in an ideal world all LED lights would have a heat sensor that switches the light to a lower level before any damage to the LED or the circuit can occur, like the HDS. This is one of the more important features of a light because it increases its reliability, and it's getting more and more important at a time when the lights are getting more and more powerful.

Hans

+1.

As an aside, threads like this make me glad I sold off my Fenix L2D CE before it broke, melted, or sucked the batteries so low they they vented and ballooned the rubber tail cap. :nana:

Chinook · Jun 24, 2007

ensile said:
switched my p2d to Strobe and sat it directly under the mirror ball at a friends party last night, it was crazy, then SOS, but that was annoying, i settled on low mode and it was a comfortable slow spinning sparkle.

uh... what were you wearing??

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