Modders: Q5 direct drive question

[webley445]

I have a dereelight module that got fried. So I rigged it to run direct off of two CR123's.
Man it is bright! Blows my Fenix P3D Q5 on turbo into the dust!

But what now/ What will be the long term repercussions of doing this?

 

[TigerhawkT3]

Lifetime of the LED will go WAY down. How far, I don't know, but I wouldn't rely on it. You should probably put a resistor in there (3, maybe 5Ω).

 

[mmmflashlights]

Nothing wrong with direct driving an LED, at a reasonable voltage that is.... Direct driven off of 2 Lithium Primaries with a total voltage of over 6 volts and not a lot of voltage sag, now that's a very bad idea on the other hand. You'll probably damage the LED within minutes.

 

[webley445]

Will the resistor diminish output?


Some quick pics:

Dereelight Mod

P3D Q5 Premium onTurbo

 

[mmmflashlights]

Yes, and how much it drops it depends on the resistor used.

I would buy a cheap circuit from DX or KD, gain regulated output, multiple modes, etc.

 

[webley445]

Will check them out thanks.

 

[kramer5150]

could the OP use a single 18650 and not need a resistor?

 

[TigerhawkT3]

Yep, that should be fine.

 

[Gunner12]

But the LED will be overdriven at the start of the runtime(less then it is now though, with a 18650).

I'm surprised that the LED didn't burn out, but then batteries do have an internal resistance.

 

[webley445]

I realized the batts had some use so probably worn down a little but not too much.

 

[TigerhawkT3]

With the CR123As, current probably didn't go above 2.5A or so, since that's pretty much their limit. The Li-Ion is a more acceptable choice, but still overdriving a bit, especially with a fresh cell. With good heatsinking, heat damage and lifetime reduction should be minimal.

 

[Superdave]

I had an ebay Q5 P60 drop in on the bench the other day, @ 9V input (to the regulator) the Q5 was seeing about 3.3V and total draw was about .5A

LED's need some kind of current limiting, even 1 resistor in series would help it last a bit longer.


BTW, a Q5 direct driven in a AA-Mag will last for a very long time... not very bright though.

 

[Nitroz]

I have a dereelight module that got fried. So I rigged it to run direct off of two CR123's.
Man it is bright! Blows my Fenix P3D Q5 on turbo into the dust!

But what now/ What will be the long term repercussions of doing this?

You're just asking to let out the magic smoke.