Confused!! What's the deal.

lightinsky · Jan 18, 2009

Why are some cree p4's only 120 lumens and others 180. Some are listed on ebay as 200 and 240 lumens. Now I'm sure these are inflated and not bulb emitter actual lumens but can a p4 be brighter than a Q5 while being less efficient. Help is needed to understand.

Marduke · Jan 18, 2009

The current being sent to the LED by the circuit is what determines brightness, not just the LED itself.

FlashCrazy · Jan 18, 2009

It depends on the drive level (amound of current sent to the LED) of the particular flashlight. A P4 driven at 1000 mA may be the same brightness as a Q5 driven at say 750 mA, but the Q5 will have a longer runtime.

lightinsky · Jan 18, 2009

FlashCrazy said:
It depends on the drive level (amound of current sent to the LED) of the particular flashlight. A P4 driven at 1000 mA may be the same brightness as a Q5 driven at say 750 mA, but the Q5 will have a longer runtime.

Oh I see! I have a Cree P4 (Dx1447) rated at 900 mah in my G2 and my Solarforce Q5 in my 6P I think is 650 mah are pretty close in brightness since when I compare the two the Q5 is noticebly a little brighter.

Gunner12 · Jan 18, 2009

They are both Cree XR-E LEDs. The difference is the flux bin and maybe the tint bin(the flux bin is the output/efficiency bin). The XR-E is rated up to 1000 mA but can be drive at any current. Too much will kill the LED, too little won't get the output needed.

The Cree XR-E Q5 driven at 650 mA should have around the same output as the Cree XR-E P4 driven at 900 mA(no visible difference by eye). The difference you see might be a difference in tint.

Big_Ed · Jan 18, 2009

Pure marketing B.S. I wouldn't trust any of those ratings on ebay.

lightinsky · Jan 18, 2009

Gunner12 said:
They are both Cree XR-E LEDs. The difference is the flux bin and maybe the tint bin(the flux bin is the output/efficiency bin). The XR-E is rated up to 1000 mA but can be drive at any current. Too much will kill the LED, too little won't get the output needed.

The Cree XR-E Q5 driven at 650 mA should have around the same output as the Cree XR-E P4 driven at 900 mA(no visible difference by eye). The difference you see might be a difference in tint.

I'm not sure that the Solarforce Cree Q5 I have is 650 mA that I got it from ebay. Ebay says at 6 volts it's rated at 225 lumens. I think someone on CPF said that there estimation of that drop in is was 650 mA. On DX's website the Cree 1447 says it has a 900 mA driver board. I do notice that the Q5 outthrows the P4 and is a little brighter. So lumens may be pretty high on the DX P4 driven at 900 mA.

Confused!! What's the deal.

lightinsky

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Marduke

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FlashCrazy

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lightinsky

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Gunner12

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Big_Ed

Flashlight Enthusiast

lightinsky

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