Latest LED technology question...

[jaundice]

Reading this forum in depth, and pouring over flashlight specs and reviews, it's very clear that the latest generation of LEDs have made a large leap over the previous generation. You see the fenix TK11, Malkoff M60, and Eagletac T10C all running 230+ lumens for 90+ minutes on 2 primaries, or 60-80 lumens for 8-10 hours, solid. Just recently, an Inova XO3 would give you 60 lumens for 2 hours, or a Surefire KL1 30 lumens for 3 hours, regulated.

My question is this: What are the main drivers behind this huge improvement? I realize the emitters are much more efficient, but how much so (percentage or factor)? To what degree is the driver technology increasing performance?

One of the reasons I'm asking this question is that I have a surefire KL1 (4th model) and I like the physical package a lot. Is it worth paying a modder to upgrade the emitter, if the driver stays the same, or should I just sell it and buy a newer LED head? I like the KL1's wide input voltage range, but is it drastically limiting the performance?

Thanks,

-John

 

[PhantomPhoton]

The latest generation of LEDs to come out, Cree being the frontrunner, are almost double the efficiency than the Luxeon III's, old K2's, Luxseon V's.

While I kind of have a technical idea of why they're so much better, not being a semiconductor engineer I couldn't state it in a satisfactory way. But sufffice to say the Blue dies got extra light going forward where it was once lost, and phosphor coatings have gotten more efficient as well.
Drivers are getting better, though they aren't a major factor in the sudden jump that started a bit over 2 years ago.

Slightlytechnical LED questionslike this would likely get better answers in the LED subsection a bit further down. This thread will get quickly buried in the second page in the LED flashlight section. :thumbsup:

 

[jaundice]

Phantom Photon;

Thank you for your answer, and you're completely right. I'm kind of new here, and haven't yet explored that far down the forum, yet!

Mods;

Please move this thread to the Beyond Flashlights: LED.

-John

 

[DM51]

Correct suggestion - I'm moving it now.

 

[SemiMan]

There have been ongoing improvements to process technology that are responsible for the gradual 10% here, 5% here, etc. improvements. One big leap came with thin-film technology and that is where the sudden almost 2x jump came in a few years back.

Semiman

 

[rushnrockt]

There are also improvements in thermal packaging that allow the LEDs to perform optimally at higher currents.

 

[spencer]

Isn't improved runtime contributed to battery advancements as well?

 

[asdalton]

Isn't improved runtime contributed to battery advancements as well?

It's mostly the LEDs.

The old version (Luxeon III) of the Surefire E2L ran for 2.5 hours in regulation at about 40 lumens. That's 100 lumen-hours from a pair of 123A lithium batteries.

The 2007 version of the same light (Cree) ran for 9 hours in regulation at about 50 lumens. That's 450 lumen-hours from the same pair of batteries.

In this case, the difference in runtime is a little misleading, because the Cree LED is about 2x as efficient as the Luxeon, not 4x. But there are two things that work in your favor when you use a more efficient LED but maintain the same light output:

1) You are drawing less current from the batteries. The lower current strains the batteries less and allows them to deliver a larger portion of their energy before the regulator circuit can't keep up. So the batteries play a role, but the battery technology here has not changed.

2) You are driving the newer LED at a lower current, and therefore in a more efficient part of its output curve. So if the newer LED is 2x as efficient as the old one at the same drive current (which is the right way to do the comparison of efficiency), the efficiency difference will be even larger if you are driving the newer LED with less current in order to get the same output.

 

[jaundice]

ASDalton;

Thanks for the great answer. It's just what I was looking for.

To drill down a bit deeper into your answer, how about this:

I have Surefire KL1 led module (the older Luxeon III from the first E2L you mention, I believe). I like it because the driver takes input voltage from 3-9V, allowing it's use from anything from 1-3 primaries or up to 2 rechargeables. If I want to keep this functionality, but get more effciency, can I upgrade the emitter to a current model and see the improvements you're talking about? Is this worth it? Or should I buy a new led module?

Can you suggest an LED that would give me ~45 lumens for the max amount of runtime? (I really new at this)

Also, can you clarify that the 2007 version of the E2L carries the KX2 head?

Anybody else, feel free to chime in!

Thanks!

-John

 

[Gunner12]

You'll have to modify or get a new driver to get 45 lumen with a current gen LED. If you just swap the LED, you'll get twice or more output but with the same runtime.

Wrong infoI think the E2L with the Cree LED came out last year, so the 2007 E2L probably used the Luxeon LED). I'm not sure about this though since I'm not that good with Surefire lights.

Edit: The 2007 version of the E2L had a Cree XR-E LED and was single mode. I knew it sounded wrong when I posted.

 

[asdalton]

I think the E2L with the Cree LED came out last year, so the 2007 E2L probably used the Luxeon LED.

No, the version of the E2L that came out in 2007 used a Cree and had 1 level. The current revision was released in 2008 and has 2 levels.

Before then, the Luxeon III version of the KL1 (used in the old E1L and E2L) was released in 2004 and had no changes until the first Cree version in 2007. At the same time when the first Cree versions were released, Surefire decided to split up the functionality of the old KL1 into two LED heads operating at different voltages: the KX1 for 3 volts, and the KX2 for 6 volts.

 

[Gunner12]

No, the version of the E2L that came out in 2007 used a Cree and had 1 level. The current revision was released in 2008 and has 2 levels...

Edited, thanks.

I had a feeling that I was wrong when I posted, thanks for correcting me.