Best Lux-V VF for 7.2V DD mod ?

shiftd

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i melted a T Vf before (yeah, that T!!!! /ubbthreads/images/graemlins/banghead.gif). it is pulling from 2 fresh 18650 li-ion in excess of 2 amps. It was heatsinked properly (as proper as it can be anyway) and the heat is not dissipated enuff from the junction. Well, nice bright white then died /ubbthreads/images/graemlins/frown.gif

I would say use a resistor, a 5W .5 ohm resistor would be a safer way to drive 5W from 2 li-ion.
 

modamag

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HgRyu, my LuxV VW0T pulled 1.56A @ 6.9V and 2.44A @ 7.3V.
It got hot in a HURRY!
I definitely second shiftd's recomendation of resistoring the baby.
It also depends on what type of NiMh you got some have higher resistance than others.

Happy Modding,
Jonathan
 

evan9162

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6 NiMH batteries fresh off the charger will total over 8.4V. You're still flirting with disaster. Even if you get a high enough Vf bin to make things safe at first, Vf will drop 0.3-0.6V in the first 100 hours of use, causing current to probably double.
 

Timson

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I have a Lux V 2D Mag mod with an emitter Vf of U
The Lux is driven DD from 6 x Uniross 2300Mah NiMh AA's in EL's 3 to D adapters.
With cells fresh off the charger it draws 850Ma
After some use it is drawing a steady 1/2 amp.
Driven off 3x123 and 3/4ohm resistor - it draws about an amp. I recon there's about half an ohm resistance from the mag switch/contacts.
 

evan9162

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Timson,

If you're using the 3-D version 1 adapters, there's something like 1 ohm per adaptor of additional resistance.
 

modamag

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Even the v2 3AA-1D adapter you can get 1.6 Ohms of resistance each if you don't sand/clean the contacts.
 

Timson

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/ubbthreads/images/graemlins/wow.gif I had no idea there would be as much resistance as that. This explains my low current draw.
What about 'Fivemega's' 6AA to D adapters...Are they a significantly better option?
I think he still has some available on his group-buy...Hmmmmm.

Cheers,
Tim
 

HgRyu

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Hum...
It's becomming more confusing.
I plan to make direct drive (with no resistor) Lux-V mod using 2D Mag and V2 3AA to D holder and batteries Sanyo 2500mA Nimh.
Then wat is your VF suggestion for this setup ?

Thank you again for your comments.
 

Timson

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I recon you'd get away with a Vf of T.
Should be a real blinder! (Pun intended)

Just make sure that you heat sink properly - 'Hotlips' or 'O Sink' are perfect - with the emitter 'arctic Alumina'd'(Thermally conductive epoxy)in place.

I'd let the cells rest for an hour or two after charging before trying them in the light.
You might find that after you've run a dozen or so sets of batteries through the light that the Vf has dropped further and you'll be pushing big current through the emitter and would need to add resistance - Having said that your High Capacity cells may not be capable of delivering really high current levels.
(Someone here might know)

A Vf of 'U' will definately be safe, you won't have to worry about the Vf shift as it ages - it will improve with use.
As I said before I get about 850 Ma with cells fresh off the charger through my 'U' with your proposed set up.
This is a nice current level but it drops off too quickly as the battery voltage sags.
That's why i'm going to try one of Fivemega's battery carriers - which should reduce the internal resistance.
Either way it's a really nice light even if it's not the brightest of its kind. The Sandwich Shoppe has some nice white U voltage Lux V's at the moment.

If you want a 'WOW light' but don't intend to put lots of hours on it - go for a T

If you want a safe 'Workhorse' get a U.

That's just my take on things - Either way give it a try - you can always change things later - Thats half the fun of modding!

Good Luck,
Tim
 

modamag

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HgRyu, for $16-$22 more you can get it regulated and not worry about all this. With dimming capability too /ubbthreads/images/graemlins/grin.gif

But if you still want a ~100% efficient circuit then I would go for the U-Vf like Timson said. If the light is bright but it doesn't last that makes it an "incandescent" /ubbthreads/images/graemlins/crackup.gif
 

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