Overdriving a Q5

[MMACH 5]

I bought one of these a while back and am quite pleased with its throwing ability.
UniqueFire HS-802
http://www.dealextreme.com/details.dx/sku.16538

I use it on my bicycle for commuting and after dropping it a few times, the emitter came apart and conked out. I replaced the dead, R2-WC emitter with one of these.
Cree XR-E Q5 Emitter
http://www.dealextreme.com/details.dx/sku.2394

Now I have a few of these Q5 emitters sitting around and was just sort of goofing around with one of them and a 18650 battery. Directly driving the Q5 was amazing! I've seen at least one thread on here about doing this, but I don't think I want to push it that far. Mainly, I don't want to reduce my run-time by that much; I'm getting over two and half hours with the light now and direct-drive would bring it down below an hour. Obviously, I'm going to sacrifice some run-time for brightness, but it would be preferable to keep it in between these two examples.

I measured the draw on the light, as it is now at 210mA. On direct drive, the meter pegs out somewhere above 250mA, (my meter doesn't go any higher).

Which brings me to my inquiry: What pill, circuit or puck could I use to overdrive my light?

Maybe this?
http://www.dealextreme.com/details.dx/sku.25518
or this?
http://www.dealextreme.com/details.dx/sku.25505

 

[Mark620]

this will (theoretically) drive at 1 AMP(1000mA): What is your Battery Capacity?
http://www.dealextreme.com/details.dx/sku.25518

this : Well, you may never get it...
http://www.dealextreme.com/details.dx/sku.25505

 

[MMACH 5]

Thanks.
My batteries are 3.7V 2400mAh.
http://www.dealextreme.com/details.dx/sku.19624

 

[J_C]

I am suspecting your meter isn't giving you the right current reading, after all you wrote over 2 1/2 hours so if we call it 3 off a 2400mAH cell, even if it is only capable of less like 2000mAH, that's still closer to 700mA than to 210mA.

but still it seems you want higher and that's ok!

Mark's first linked driver may work but the 2nd probably not too good, 2nd one appears to be direct drive above the Vf of the LED despite it's rating up to 4.2V (as with most of the DX lights and drivers).

 

[Mark620]

The first "driver" is not much more than a glorified resister (they look like AMC7135's).
If so, that "diver" is set for 1050mA, extra current is turned to heat.

Don't get me wrong, you need a current controller of some type in most applications.

 

[J_C]

True, linear regulators are lossy, but with a cell voltage not much above the LED forward voltage you're taking a significant efficiency hit through a more elaborate driver too. Drop across a schottky diode alone is not much lower if any compared to a 7135 drop.