Cree 3W versus Cree 4W versus Luxeon 6W

[umberto]

First of all, what is the diff really between the Cree and the Luxeon ?

I recently bought the 6W luxeon Dorcy, run by (2) 123's and this is extremely bright. But since discovering this forum, I see a Rayovac 4W Cree 3 'C' batteries, and the Task Force 3W Cree run by 2 'C''s at Lowes.

Could someone comment on these three lights, and does the diameter of the head of the flashlight really make a difference in determining which LED flashlight will put out the most light?

Any guesses on approximated run times with these three lights/battery arrangemnets?
thanks

 

[INFI]

The diameter of the bezel does not dictate the output of a flashlight. It effects the throw/sidespill of the light but not much else. If I am wrong someone please correct me. Sorry I can't answer some of your questions. But some of the pros will be by shortly, also the CREE company puts out the latest and greatest LED's compared to the Luxeon.

 

[bessiebenny]

There's a whole thread on Task Force 3W Cree. So check it out.
http://www.candlepowerforums.com/vb/showthread.php?t=175576

That 6W Luxeon would be quite bright. But newer flashlights using LEDs such as Cree and SSC and Luxeon Rebel's are generally brighter while consuming less power. (Such as that 3W Cree) So don't assume more "Watts" = more brightness unless you know the entire specs. Whatever it says in the packaging doesn't always translate exactly to its brightness.

No idea about run times...

 

[Gunner12]

A 3W Cree and a 4W Cree have no difference, just that one is presumably driven harder and thus brighter. The Cree and the Luxeon V produce about the same amount of light but the Cree has a smaller die(about 4x smaller) and a lower Vf and is more efficient.

 

[LEDninja]

Watts is drain on batteries, not light output. So the bigger the watt # the more money you spend on batteries.

The Dorcy 6 watts use the K2 LED which is infamous for it's lack of efficiency. I guess the K2 is driven at 1000 mA and should give ~60 lumens at the LED, 40 lumens out the front of the light.

The newer Cree XRE, SSC-P4, rebel LEDs are roughly twice as efficient. They generally max out at 3 different levels:

1.25 watt - 300 to 350 mA
AAA lights max out at 300 mA should give 64 lumens at the LED, 42 lumens out front.
AA lights tend to be 350 mA should give 80 lumens at the LED, 55 lumens out front.

3 watt - 700 mA
2xAA or 1xCR123A or 1xCR2 or... should give 135 lumens at the LED. 88 lumens out front.

4 watt - 1000 mA
2xCR123A should give 167 lumens at the LED, 108 out front.

The latest LEDs Cree Q5 or Luxeon rebel 100 should give 25% more light so claims of over 200 lumens are now often seen.

YMMV or I should say your milage WILL vary. For example the 1AA/AAA boost circuits actually vary from 20 mA through 500 mA giving a wide range of brightness.

One important note. Alkaline and carbon zinc cells (AA/AAA) drop in voltage as they are used and so will light output of the cheaper lights with simple boost circuits. A regulated circuit will keep the voltage/current to the LED and the light output constant. NiMH and Lithium cells give a fairly constant output so a regulated circuit is not strictly necessary.

 

[umberto]

The 6W Dorcy says it puts out 120 lumens (the company wouldn't exaggerate, would they?:naughty....so you are saying that it really puts out half the lumens it says it does......is it true though that the relatively large diameter of the Dorcy's head doesn't give it an edge over the 3W cree?

 

[Gunner12]

The size of the reflector does not do anything to affect the light output. In fact, the reflector actually absorbs some of the light from the LED. I think it was 35% loss of light from the source with a normal reflector and uncoated glass window. The reflector mainly determines the beam pattern. A larger/deeper reflector usually gives the light a narrower beam and more throw. The Rayovac and Task Force Cree should easily out lumen and probably out throw the Dorcy.

 

[LEDninja]

The 6W Dorcy says it puts out 120 lumens (the company wouldn't exaggerate, would they?:naughty....so you are saying that it really puts out half the lumens it says it does......is it true though that the relatively large diameter of the Dorcy's head doesn't give it an edge over the 3W cree?

The 3xCR123A version will probably drive the LED at 1500 mA and get 120 lumens at the LED. The 2x123A version will not max out the drive current, maybe 700 to 1000 mA giving only 60 to 80 lumens.

Many far east manufacturers just use the biggest numbers they see on spec. sheets - 100,000 hours LED life is a good example - you probably will get 100,000 hours if you run the K2 at 15 mA but at the drive currents of 700 to 1500 mA it will be much less.

Note all 3 models say 120 lumens. (6AAA, 2x123A, 3x123A) if you do the CPF thing and buy all 3 you will find they are of different brightness.

It is obvious the manufacturer is just using "spec.#s" and Dorcy, being an importer/distributer is just parroting the manufacturer's info sheet.

Here is a review of the Dorcy 6 watt.
http://www.candlepowerforums.com/vb/showthread.php?t=153818

 

[umberto]

thanks for the link....as this is my first and only LED, I have nothing to compare it to, but the night I bought it, I was out in the parking lot with several of my co-workers and we were all amazed at how bright it was, esp compared to my friend's regular ol' incandescent flashlight with fresh D cells....we were extremely impressed...against the white side of our building, the cut off between the hot center and the 'spill' was distinct, so maybe they improved it over the early models (the review in the link was from 6 months ago)

 

[clg0159]

The rayovac uses 3C's and an optic, and the task force uses 2c's and an optic with a narrower transmission angle. I believe both will easily outperform the luxeon K2 Dorcy light although it is bright. More runtime from the Rayovac though considering it is not regulated and has more cells.