Too much current draw for Fenix TK-10?

BrightMan

Newly Enlightened
Joined
Nov 7, 2006
Messages
12
Location
Germany
Yesterday I got my new TK-10 and one of the first things I did was measuring the current draw (primary CR123):

General: 100 mA
Turbo: 860 mA

In another post an user measured only 750 mA in turbo mode.

https://www.candlepowerforums.com/threads/193155

Why do I read more?
This would be 5,16 W, but isn't it only a 3W LED?

Thx
BrightMan
 

baterija

Flashlight Enthusiast
Joined
Feb 7, 2008
Messages
1,053
To expand a little bit on Marduke's answer:
- The driver consumes a percentage of power.
- Under load your cells voltage will sag quite a bit from the nominal voltage of 6V. That means you overestimated power supplied by quite a bit.
- The LED is rated for a maximum current supplied of 1A not by maximum power. Cree doesn't bin for Vf so that can vary quite a bit. Looking at this thread Erasmus showed just over 10% difference between the Vf of the highest and lowest samples of R2 he measured at 350ma. "Typical" Vf at 1A for an XR-E from Cree's documentation is 3.7V. If the distribution at 1A is the same as Erasmus' data for an R2, you are roughly looking at Vf between 3.5 and 3.9 at 1 amp - 3.5 to 3.9 watts.

In summary, lots of things can vary. Vf and batteries probably being among the bigger variables. That may explain the comparison to the other thread. Raising estimates of max power, lowering your estimate of provided power, and adding in driver losses probably takes care of it looking like the LED is overdriven. Unless you are having problems I wouldn't worry.
 
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