What boost for Nexgen driver with 3W Luxeon

[wintermute]

OK, with respect to the Nexgen driver. I can order a Nexgen driver with different output options. For this mod I am thinking either the 750mA, 917mA, or 1000mA. Is the 1000mA too high? Would the 917mA be a good choice to get >1 hour of runtime on NiMH AA batteries?

 

[jaids]

How big of a reflector are you using? Is this for a sandwich? Beyond 500 ma you will overpower a 17mm reflector.

 

[wintermute]

The flashlight that I am planning to mod is the EL XM-3. Leow posted a mod in which he used a VIP 1000 board to drive the torch, but suggested that a Nexgen 1000 could work as well. His mod is posted here.

Now, with the VIP 1000 driver he was experiencing run times of 55 minutes max. Also, it seems that running the luxeon 3 at 1000mA might be a little on high side. So I was wondering if installing a Nexgen driver with output at 917mA would give an output close to Leow's light with run time just over an hour with 2.4A NiMH cells.

Leow's mod to bore out the body and change the battery type just didn't interest me. Although, I do have access to metalworking equipment, it would be a stretch for me to modify that much.

As far as the pill is concerned, it is almost identical to the pill in the flashlight that Lambda modded here. The exception is that the pill is not recessed behind the emitter, so the thermal contact with the pill is ok. Although when I am replacing the driver, I plan on using some Artic Silver behind the emitter, and I have already ordered some adhesive copper tape to wrap the pill to make better contact with the body, like Leow suggested.

I am just looking to get some more output from this light without overdriving the luxeon. As long as my run time is around 1 hour, I'm happy.

 

[jaids]

as far as brightness goes doubling the current to the luxeon will give you roughly 1.5x the light output(someone correct me if I am wrong, this is based on my own experiences) and half the battery life.
so a drop from 1A to .75A will give you 1.25x runtime with 83% of the light output.

 

[wintermute]

Since the stock driver boosts at about 600mA installing a 917mA boost driver should increase the brightness substantially then. Would a 1000mA boost circuit be too much for this light?

 

[wintermute]

anyone...anyone.

Would 1000mA be overdrive a TWOJ too much? Or would 917mA be a safter option, without loosing a lot of light?

 

[Flatscan]

There is really not much of a functional difference between a NG917 and a NG1000 in terms of heat, brightness, or runtime, i.e. you will not be able to tell on any of these characteristics without measuring instruments. Since runtime depends as much on your specific emitter and batteries as it does on drive current, you may not be able to hit 1hr on even a NG917. You're going to get somewhere near 60 minutes at either 917 or 1000. If 60 minutes of continuous runtime is a hard requirement for you, I would drop it to 750 and get good 2300mAh AA NiMHs.

Summary: 917 vs 1000 doesn't matter. If you need >60min, you might want to consider 750 again.

I couldn't find the specs on the XM-3 reflector from a quick look at EL's site. It looks like there's room for a 20mm reflector in there, doesn't seem like a 27mm would fit, but I could be mistaken. jaids's point is that running >500mA in a 17mm reflector is excessive. I can certainly understand "as bright as possible".

 

[wintermute]

The XM-3 has a 20mm reflector and a 25mm lens. So unfortunately, a larger reflector won't fit in there.

The runtime is not what I am super worried about...I was more wondering about overdriving a lux3. But I have been reading numerous posts where people drive lux3s at 1A with good heat sinking.

I think before I decide I am going to remove the old emitter, and replace it with a TWOJ...then see where I want to go with a new driver.

Also, on another note...how easy do the emitters come off of the stars? Will a little heat with a 15 watt soldering iron plus a solder sucker remove them easily?

 

[wintermute]

I just realized that the boost circuit in the XM-3 only pushes a 350mA output. Info on the board can be found here. What a joke, since on EL's webpage it clearly states:

[ QUOTE ]
The LED in this flashlight is a Luxeon Star LED, rated at 3 watts, and 72 lumens. This LED will last 50,000 hours (5 years continuous.) <font color="red"> The boost circuit boosts at about 600mA </font>, and the batteries will last about 2 hours (depending on type and quality of batteries used.) Any type of 1.2V or 1.5V AA battery will work, (nimh, nicad, alkalines, lithium).

[/ QUOTE ]

So I think I will start out with a Nexgen BB750 with a TWOJ luxeon and see what happens.