more voltage more lumens?

[john_smith2]

i seek for a led r2 cree lamp(sorry for my english before all) and i see that on the sites say that give 280 or 295 lumens , use 2x3.7 (7v) or 3x3.7 (12v) batterys ,but the same lumens output.what it´s real , for example , my brother buy a "led 240 lumes" that use 2x3.7 , how many lumens it´s real?, if i buy a lamp with 2 or 3 capacity batterys and a r2 cree what its the maximum power that i can obtain, or it´s the same of a p4 (240 lumens) or minus.
have any table with the input/output to see the real power
thanks for all
it´s boooooored, i know ,but this type of lamps are not usually on Spain.

 

[yellow]

brightness of a led is related to
a) bin ... (but not this great effect) and
b) current

Most actual ones need some 3.8 V / 900 mAh to give that output You mention (but are not tested for that output! Usually are tested with 350 mAh = 1 W)

To very roughly estimate what the led sees, measure the current draw at batteries, calcualte Voltage to the 3.8 V needed and divide. Deduct 10 % for the driver losses (if there is a driver).
Thats about the current to the led.

means: that 3 cell light draws less than the 2 cell one, offering more runtime

measure current at batt and most any here can give You the numbers (as should be from the datasheets).
Personally I dont like the Seoul and think You are better of with Cree anyway.

 

[Lightfantastic]

Regulation. It keeps the LED from overdriving and sometimes keeps it from underdriving. Advertised lumens should be taken with a bit of skepticism.

 

[LEDninja]

+1. A Cree or SSC P4 will probably turn blue and long before you get 295 lumens.

Advertised lumens should be taken with a bit of skepticism.

Do you need throw distance (measured in lux or mcp) or total brightness (measured in lumens)?
If you need lumens look at the new SSC P7 torches. "maximum 900 lumens" (actually 400-500 torch lumens) $45-$130.