Anyone direct drive Lux III with 4 C cells?

DaMeatMan

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I'm just wondering if anyone has modded one of their lights to use 4 c cells with a K bin vf. I've tried it briefly with my TWOK in my mag and noticed an insane amount of light coming out the busniess end /ubbthreads/images/graemlins/buttrock.gif, definately more then i've ever seen out of it. I am talking Duracell alkalkine C batteries though and not rechargeables. I decided to put in a 1ohm resistor in there just for good measure, but what i'm wondering is what kind of risk would i be looking at if i went direct drive instead. If i'm looking at cutting the life of the lux III in half then that is just fine and dandy for me as i plan on upgrading anyway as soon as i get my hands on something better. But has someone done any real tests or measurments, if u could throw some numbers at me i would greatly appreciate it. I would really like to direct drive this light again but if it's going to die after a couple hours of use then i'll stick with the resistor. Should i go for it?? /ubbthreads/images/graemlins/thinking.gif
 

evan9162

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No,

DD off of 4C cells, you'll probably push over 2A through the emitter. You'll be flirting with the bond wires fusing open, and will definitely be exceeding the maximum junction temperature of the LED. Lifetime will be severely compromised.
 

Chief_Wiggum

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Hmmm, I've run K Vf Lux IIIs from 2 CR123s direct drive and I know another guy who has too /ubbthreads/images/graemlins/smile.gif It's bright...really bright. No runtime, heat, or longevity measurments though.
 

DaMeatMan

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How many amps do you figure i'm pushing through it now with 4 C Alkaline Duracell's with 1 ohm of resistance? I really need to buy myself a decent meter capable of reading current so i can take my own measurements.
 

Rothrandir

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poof....(eventually)

back over a year ago, i ran a 1w ld on 4c's for several minutes, before the light went out...

so yes, it would probably work, but for how long? /ubbthreads/images/graemlins/icon15.gif
 

Sway

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DMM,

I killed a TWAK running 2x123's, anything over 4.5V and 1 amp is wasted in excess heat and overdriving the LED to an early death. YMMV just flashing around it may liver longer but in a run test it will last one or 2 sets of batt's and it will be time to summons the undertaker.

R.I.P TWAK /ubbthreads/images/graemlins/mecry.gif

Later
Sway
 

DaMeatMan

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I'm gonna be experimenting with a bunch of different battery combo's. Right now i'm setting up to power up the TWOK with 4 AA's to get a rough idea of how long it will run on that. If the run time is decent i eventualy plan to run the mag on 4 set's of 4AA's for a total of 16 AA Nimh batteries 1600 mah each cell. Why you may ask? /ubbthreads/images/graemlins/thinking.gif Because i happen to have a bunch of AA rechargeables lying around, and it would be the cheapest way for me to power up the light without spending a dime on replacing batteries. But if i did that what do you think would be a suitable amount of resistance to use to keep the current flow at around 1.2 - 1.5 amps?
 

Doug S

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[ QUOTE ]
DaMeatMan said:
...i eventualy plan to run the mag on 4 set's of 4AA's for a total of 16 AA Nimh batteries 1600 mah each cell. Why you may ask? /ubbthreads/images/graemlins/thinking.gif Because i happen to have a bunch of AA rechargeables lying around...

[/ QUOTE ]
I hope you have a good supply of emitters lying around too /ubbthreads/images/graemlins/wink.gif
 

evan9162

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[ QUOTE ]
DaMeatMan said:
How many amps do you figure i'm pushing through it now with 4 C Alkaline Duracell's with 1 ohm of resistance? I really need to buy myself a decent meter capable of reading current so i can take my own measurements.

[/ QUOTE ]

Probably over 1.5 amps.
 

DaMeatMan

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Actually ya i do.. i wouldn't be so keen on experimenting unless i had some backups lying around. I've got another TWOK emitter and a SWAK. /ubbthreads/images/graemlins/wink.gif I've yet to fry my first luxeon, and if i do at least i'll learn somethin about what they can and cannot tolerate. I'll keep you guy's posted.
 

Sway

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[ QUOTE ]
Doug S said:
I hope you have a good supply of emitters lying around too

[/ QUOTE ]

And the undertaker commeth /ubbthreads/images/graemlins/eek.gif
 

unnerv

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I had created a 4AA on an SWOL in a mag, and on fresh batteries it draws 1.8 amps. I have about 2 hours of on/off runtime, with it being used for 25 minutes at the longest stretch. The batteries at near end of life still draws 800ma, these are alkys that even with no load only show 1.25v on the meter. For anyone interested in the mod I have a nice long write up here
 

TheFire

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Man, start with the SWAK. The good T bin emitters are getting hard to come by, these days...
 

DaMeatMan

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Well the reason i'm testing on the TWOK is because it's already in a 3D mag with the hotlips heatsink and a 1 ohm resistor. Also to be honest with you i kinda like the colour of the SWAK better then the TWOK, the TWOK seems bit to warm for my taste while the SWAK is much whiter.
Anyhow last night i tested the TWOK setup with 4 AA LEAP brand rechargeable batteries which are rated at 1600 mAh each. After a full charge they were reading about 1.4 volts each for a total of 5.6v. I started the runtime test and continuosly monitored it's temperature by hand to make sure things weren't going to fry. At about 1 hour in it was probabally it's warmest, but still not hot and definately not something to be concerned about. I don't have a light meter so i decided to end the testing when i figured the beam had reached about half it's initial brightness. The way i determined this was by comparing it to the beam of my Blaster III, i know the blaster put's out roughly 5000-6000 lux and the mag roughly twice that number. So when i could no longer superimpose the mags beam over the Blaster then i called it quits. This happened at about the 2.5 hour mark, and the voltage had now dropped to 4.7 volts. I was really quite surprised it would last that long. Anyhow the beam was still very usable and i'm sure would have lasted for many more hours b4 completely dying on me. The test results were in and i was really quite satisfied, i will run some more tests later with 2 sets of 4 AA's later today or tomorrow. I do want to purchase some more resistors before i make my way to 4 sets of 4 AA's though just to be sure things don't fry. But by my logic i should be able to get about 10 hours of runtime out of the 4x4 AA setup before it reaches half it's brightness, and if that's the case then i am more then satisfied. /ubbthreads/images/graemlins/thumbsup.gif
 

Steelwolf

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[ QUOTE ]
DaMeatMan said:
I really need to buy myself a decent meter capable of reading current so i can take my own measurements.

[/ QUOTE ]

You don't really need to. Measure voltage across the 1 ohm resistor you have there. If your resistor is fairly accurate, the voltage you measure is the current running through the resistor. V = I*R
 

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