Call me crazy but...

Hey guys, first post on the forums here so go easy on me. I have done nothing but research on here the last couple of weeks. I went out and upgraded from the Fenix L2D to the TK11. Bought a Pila charger and some 600P batteries also.

To my question, I had a suspicion before I bought the TK11, but it seems like over time, the L2D is no longer putting out the same light as when it was new. I just tried some brand new lithium primaries in the L2d, Vs the TK11, and there is like a mega difference. On paper it should be 180 lumens Vs 225 lumens. And yes I am definitely in turbo on both of them. The L2D hasnt seemed bright in quite a while (since my buddies got some P3D's). Something just doesnt seem right with it. Tried cleaning the contacts on it as well.

Is it possible for an LED to lose some of its output capability over time. In all honesty, there were times when I had the L2d in turbo mode for longer than the suggested 10 mins. Could this have harmed it?

Or......am I just crazy?

mutabi said:

Is it possible for an LED to lose some of its output capability over time. In all honesty, there were times when I had the L2d in turbo mode for longer than the suggested 10 mins. Could this have harmed it?

Or......am I just crazy?

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Yep. Overdriving the LED will result in decreased output over time.

Those lumen ratings are made up, so it could be a matter of newer LEDs and different driving batteries and circuits actually making those torches brighter.

OTOH, I think the L2D takes way too long to warm up for doing 700ma, and being so small around the pill (poor thermal path).

The TK11 has around 200 something actual out the front lumen as tasted by some members here. The L2D-CE Q5 on the other hand is probably around 150 lumen out the front.

Also do you have the Q5 version or the older version?

Hogokansatsukan said:

Yep. Overdriving the LED will result in decreased output over time.

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yep, what he said is right, I learned that the hard way with direct driving lights.:shrug:

Also do you have the Q5 version or the older version?

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I have the newer Q5

yep, what he said is right, I learned that the hard way with direct driving lights

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direct driving lights as opposed to the other kind which would be ....?

So I assume then that my TK11 will also be vulnerable to this as well? Although I have noticed it doesnt get near as hot as the L2D due to it being physically larger.

The L2D is not overdriving the LED. The LED is rated up to 1000 mAh(and people have pushed it way past that) and the L2D drives it at around 700-800 mAh from what I remember.

The 10 minute limit is for the times when you work under the sun during noon in a desert(or any similarly hot place) or have the light on turbo by itself in a well insulated area like a coat pocket or standing by itself on a table. The warning is for high ambient temperatures or well insulated areas.

Also remember that a narrower and more powerful hotspot can make a dimmer light seem brighter then a brighter light.

mutabi said:

direct driving lights as opposed to the other kind which would be ....?

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Having a circuit between the LED and battery that is more complex than a resistor, generally.

Gunner12 said:

The L2D is not overdriving the LED. The LED is rated up to 1000 mAh(and people have pushed it way past that) and the L2D drives it at around 700-800 mAh from what I remember.

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Until you're well above that, current is not a problem. It's heat. Driving the LED beyond it's rated temperature is also overdriving. For our uses, it is a more important measure of safe drive level, though complicated (degC/W of the flashlight in various conditions matters, not just a current or power drive value).

cerbie said:

Until you're well above that, current is not a problem. It's heat. Driving the LED beyond it's rated temperature is also overdriving. For our uses, it is a more important measure of safe drive level, though complicated (degC/W of the flashlight in various conditions matters, not just a current or power drive value).

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Good point. I don't remember seeing anything about the L2D dieing of heat yet though. The LED could have been damaged but I think the beam pattern difference and the two different ways of rating output gives a bigger visible difference then the LED degradation(which is natural, heat accelerated it).

It's like it is with computers. A computer seems fast enough until you try one faster.

Chip weevils.

LukeA said:

Chip weevils.

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i thought those were a joke!