Questions about flashlights

dttomcat

dttomcat

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Apr 14, 2007
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I was just reading through a thread in a different forum here on BFC and I began to wonder about the accuracy of the data presented on a couple of the manufacturer's websites. Surefire's website indicates that their G2 model with a standard (not the high output) xenon bulb runs for 60 minutes and that the output is approx. 65 lumens. The LED version of the same flashlight (The G2 LED) which operates using the same power source (2 CR123 lithium cells) runs for 12 Hours and the output is 80 lumens. Even though the LED is a bit more expensive it would still be the clear choice based on these numbers.

Then I visited the Streamlight website and researched their Scorpion model in both Xenon and LED versions and came up with the following information. The Scorpion xenon model (which runs on 2 CR123 lithium cells) runs for 1 hour at "up to" 114 lumens output while the LED version of the Scorpion runs for only 1 and 3/4 hours at an ouput of only 47 lumens. Does this make any sense? What am I missing?? Would anybody who has some practical experience with either of these flashlights please chime in.

One company's LED version runs for 12 times as long and has a far superior output (compared to that same company's xenon model) and the other company's LED version runs for less than twice as long but has a far inferior output (compared to THAT same company's xenon model). This does not compute. What am I missing? Thanks. -DT
 
Not all LEDs nor control circuitry are made the same. Then again, that's about the extent of my addition to this subject :p

Seriously, though, that big a difference does make me wonder, but in general, some LEDs are more efficient than others.
 
Lucky Bob,
Thanks for the input. I'm determined to get to the bottom of this. -DT
 
Most flashlight manufacturers grossly exaggerate lumens and runtime. Surefire doesn't, which confuses some people.

Voltage step-up circuitry is not very efficient -- losses are often around 50%, but vary a lot between different flashlights.

Some flashlights that don't have voltage step-up circuitry use resistors to lower the voltage, and that involves some loss too.

Look at the tests posted by enthusiasts at www.candlepower.com
 
Thank you, Sir. I will figure out what's going on here and, report back, once I do. -DT
 
It all depends on the strength of the LED bulb. Maglite makes a really strong LED which is why I use one because it is more affordable. I am looking for a SureFire or similar with the compact size for my duty belt because for the limited time I use my smaller lights the battery time doesn't concern me as much. The main reason I carry the smaller light is for when the power goes out the rest of the time it's a LED 2 D or C maglite.
 
It's not just the factors mentioned above but the generation/make/model of the LED itself which will wildly change performance. I think that Streamlight still uses old Luxeon emitters in their LED lights while the new Surefire G2L (or whatever the correct model designations is) uses a Cree LED.

To make an analogy to the computer world, it's like comparing a new Pentium chip to a couple year old chip. The current LEDs really are advancing at a rapid pace, and a state of the art LED these days is more than twice as efficient as the best LEDs from a few ago (which is when Streamlight I think last updated the LED in their Stinger). That means your choice of more than twice the brightness, more than twice the runtime, or a compromise between the two.

Yes, many manufacturer's also exaggerate specs in one way or another, but if you buy a new light with current LED technology (like Cree, Seoul, etc) you can be sure that you are getting a product that is far more efficient than the Stinger.

It's also worth noting that the Surefire G2L's advertised runtimes include the trailing decrease in brightness once past the regulation stage. Other lights may be set to regulate through the battery life (I don't know what the regulation on the Stinger LED is like though). Here's one of Chevrofreak's runtime graphs for the LED module used in the Surefire 6PL/G2L: http://lights.chevrofreak.com/runtimes/Surefire P60L/SureFire P60L.png
 
Great info all. Thanks for the link , Totc. That's what I love about BFC. There is an abundance of experience and expertise and just about everybody is willing or even anxious to share. I think I will go buy a G2L and see how it works. Thanks eveyone! -DT
 
Surefire's P60L module uses a Seoul LED, not Cree.

When you see those huge (and I think dishonest) numbers, the manufacturer is quoting the emitter's lumen rating, without taking any losses into account (i.e. from the reflector, power source, heat, etc).

Surefire uses a lumen rating that's truthful and measured from the front of the light. It's a better representation of a light's output.

-dan
 
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