How do cold temps affect LED?

Hi all,
New guy to the site so please go easy on me. First question out of the blocks, do extreme cold temps prevent a LED light from working properly? Do factors involve a voltage drop of batt pack? One of the past couple of really cold nights my magcharger with TLE-100EX/Cree would not fire up. The temp was definitely below 20 degrees and the light was in my car all day and night. After starting car and warming the light with the heater, the light worked normally. The batt pack is new and was fully charged.

Thank you for any feedback

Cold won't bother LED's, but most batteries don't like to go much below freezing, and will stop working when the electrolyte freezes.

Lithium primary is the only chemistry that's good for VERY cold temps.

OK - I usually have two magchargers in the car at all times for work. Two of them still have incan bulbs and even in the coldest temps have always worked. I really like the Cree, but it is essential that it works when needed. Are there options for batts in the magcharger other than the standard?

:welcome:

Get rid of that hulking beast and buy a surefire LED light

They have always worked great in the cold Michigan winters.....no problems!

Thanks for the welcome!

Due in large part to the info garnered here, I now own several outstanding LED lights. Still attached to the mags for multi use tool - Old habits die hard! Maybe time to retire them.

LED's dislike the heat more than they do the cold. I'm guessing the LED is not the problem. When you think cold you think batteries but at the temperature you mention I question if it would completely inhibit the battery from functioning, and like you say your Incand work at that temperature. There could be another component between the battery and LED that is the problem. Electrical components can be finicky but again usually from heat. Also at less than 20F many things contract and you could have a mechanical problem and not an electrical one. Especially since you say the light works fine once it warms up. I would definitely see if I could duplicate the problem.

One thing for sure you have peaked my curiosity. If you figure it out let us know.

Bill

:welcome:

The LED themselves probably won't be too affected by the cold. Heck, the might even be more efficient or can run at a higher current.

Don't retire the Maglites, mod them.

I didn't think to consider a possible internal contraction issue. I wish I had tested the light a few nights back with our record -12 degrees. I'm glad to hear from someone suggesting mod the others. Are there many batt/LED options available for these lights? Other than the TLE-100, most mods I see are not for magcharger. If I'm very limited, probably look into other options - great excuse to handle more lights at the SHOT SHOW in a couple of weeks!

:welcome:

THUMP88 said:

I I wish I had tested the light a few nights back with our record -12 degrees.

Click to expand...

ONLY -12 degrees (F?). That warm? lol.

I wish it was that warm up here. In our neck of the woods, we have highs for days on end of -20 to -25 F in January/February. I'm at -25 F right now, and going down.

In this type of cold weather (at times -50 F, and that's without windchill) regular batteries of all kinds kinda croak. Lead Acid, NiCad, Alkaline, etc.

For example, you can take an old alkaline Maglight from the house that was fully bright, put it out in the garage, (or outside) for say, 1/2 an hour or so, and turn it back on. It looks half dead, sometimes worse. Bring it back inside, and warm it back up, and it takes right off again. Same thing with car batteries. (you ever wonder who actually buys those 1000+cca car batteries?)

That's one of the reasons that I always carry a CR123 flashlight withme, especially when I'm icefishing, or out in the woods. It always works.

Just to give you an idea how cold -50 F is, do you ever wonder if your car door handle will break off when you open the door? Or why ice isn't slippery any more? Or why a hot cup of coffee, when thrown up into the air, never hits the ground? Or why your tires feel out of round for the first couple of miles in the morning? (They actually are, frozen with a flat spot.)

Just a couple of thoughts,

Lightmax

:thumbsup:

If i remember correctly from my material science class, a semiconductor does stop functioning at EXTREMELY low temperatures. But these temperatures would be unwordly. I think this happens at like some crazy temp of negative 150C or some extremely low temperature.

Look up "semiconductor freeze out" on google and there is more on this subject.

At least on earth, semiconductors won't hit these temps in a natural enviroment:thumbsup:.

davidt said:

If i remember correctly from my material science class, a semiconductor does stop functioning at EXTREMELY low temperatures. But these temperatures would be unwordly. I think this happens at like some crazy temp of negative 150C or some extremely low temperature.

Look up "semiconductor freeze out" on google and there is more on this subject.

At least on earth, semiconductors won't hit these temps in a natural enviroment:thumbsup:.

Click to expand...

You can actually get some crazy speeds/efficiencies if they are submerged in liquid nitrogen (as some computer equipment is)

The chemistry of a primary lithium and a rechargeable lithium are different - primary lithiums are right at home in temperatures all the way down to -40, rechargeables not so much. Your battery pack was probably chilled to the point that it was no longer conducting and/or some of the actual chemical components inside became frozen.

LEDs actually perform *better* in the cold; I recall a post on a thread here not long ago reporting on an LED placed in a lab freezer chilled to -80 degrees, and the light was *notably much brighter*.

LED + Primary CR123 is the ultimate cold weather setup, by a large margin over other configurations.

davidt said:

If i remember correctly from my material science class, a semiconductor does stop functioning at EXTREMELY low temperatures. But these temperatures would be unwordly. I think this happens at like some crazy temp of negative 150C or some extremely low temperature.

Look up "semiconductor freeze out" on google and there is more on this subject.

At least on earth, semiconductors won't hit these temps in a natural enviroment:thumbsup:.

Click to expand...

That reminded me of the science special on PBS tonght, "The quest for absolute zero." I'm guessing flashlights don't work at -273C. (-459F)

LED lights make a nice handwarmer too.

davidt said:

If i remember correctly from my material science class, a semiconductor does stop functioning at EXTREMELY low temperatures. But these temperatures would be unwordly. I think this happens at like some crazy temp of negative 150C or some extremely low temperature.

Look up "semiconductor freeze out" on google and there is more on this subject.

At least on earth, semiconductors won't hit these temps in a natural enviroment:thumbsup:.

Click to expand...

Well, thats not quite it.

You have to difference between semiconductors and doped semiconducters.

"normal" Semiconductors are "frozen" at room temperatur (thats part of the definition). Conductance and Valance bands dont overlap, and there is only a tiny fraction of electron/hole pairs created by the bolzmann-tail of the electrons. (thus heating will increase conductivity).

If you dope semiconductors, you _want_ electrical conductivity at room temperature. So you put atoms in which lie just above the valence band, or just below the conductance band.

At room temperature, nearly all of them will have donated/accepted their electron and created a conducting hole/electron.
If you cool down the material enough, this wont work anymore: the occupation of the bands will drop exponentially. But thats only at deep temperatures (like a few meV), and only affects the conductance (which is most important in computers, no mosfets without it..), but doesnt _directly_ affect the light generations in LEDs.

(otoh, current distribution on the led-die, if created by a doped layer/ect, would of course suffer).

IMSabbel said:

Well, thats not quite it.

You have to difference between semiconductors and doped semiconducters.

"normal" Semiconductors are "frozen" at room temperatur (thats part of the definition). Conductance and Valance bands dont overlap, and there is only a tiny fraction of electron/hole pairs created by the bolzmann-tail of the electrons. (thus heating will increase conductivity).

If you dope semiconductors, you _want_ electrical conductivity at room temperature. So you put atoms in which lie just above the valence band, or just below the conductance band.

At room temperature, nearly all of them will have donated/accepted their electron and created a conducting hole/electron.
If you cool down the material enough, this wont work anymore: the occupation of the bands will drop exponentially. But thats only at deep temperatures (like a few meV), and only affects the conductance (which is most important in computers, no mosfets without it..), but doesnt _directly_ affect the light generations in LEDs.

(otoh, current distribution on the led-die, if created by a doped layer/ect, would of course suffer).

Click to expand...

Hehe, Yeah sounds good. It's been a while since I learned that stuff.

Well since it was suppose to get very cold last night here in Mentor, Ohio I decided to place three flashlights in my car. My car sat outside in the driveway all night. Coldest temp recorded last night was 13.1 degrees F.
When I checked the lights this morning temperature was still 13.4 F.

Fenix L2D-Q5 2 Duracell Alkalines. Fired right up.

Surefire E2e 2 Panasonic lithiums. Fired right up.

Nitecore DI 1 Ultrafire Lithium 14500. Fired right up.

Bottle of water left in the car. Frozen.

All lights were so cold they were uncomfortable to hand hold without gloves on.

Conclusion: As I suspicioned I don't think the batteries was your problem unless there was something wrong with the batteries. Old or defective in some way.


Bill

This thread got me thinking. I think I'm gonna go throw one of my lights out in the snow for a couple hours and see how it likes it. :sick2: Now I just need to pick which one. :thinking:

- Chris

Snowmobiling in -6 degree temps and my 1AA Seouls work fine with alks.