Longbow upgrade with XM-L

Whats the biggest LED anyone has put into a Longbow capsule?

I just finished putting together a Longbow capsule with XM-L LED and only just managed to jam 2xGD1000 drivers for a 2A feed to the LED. Wow, lots of light coming out of old Longbow light now, using a 17670 battery. :naughty:

But, after a little over 2min run time (sitting on table not in hand) the light gets fairly warm (well the light is pretty small). Also the TIR lens doesnt give a nice beam with the XM-L like with the original LuxIII LE, but the reflector seems to work well.

I got a Shiningbeam driver and a triple XP-G into mine. I only use high for short spurts and medium for most tasks. That cuts down on heat.

Modded Longbow is fun, no?

Rich

Yeah its a nice well built little light, quick and easy to upgrade. Always fun to see such a little light put out so many lumens...

A couple quick and dirty iPhone photos of the Longbow;



The business end



With reflector installed.



Light is about 1.5m from the the wall.

Wolfy I have the exact same longbow in standard form. I also am in Australia - Where did you order the parts - what parts exactly did you install as I am keen to upgrade. Yours looks great - I use it for scuba diving so heat will not be too much of an issue in my case I don't think.

Rather than try upgrade the original light engine (cleaning out the old epoxy didnt look like it would be fun at all), I instead went to the sandwich shop which has empty longbow capsules on their price list and bought a couple.

Then I simply added a 13mm driver (I stacked two GD1000 in my case for 2A feed, also available from the sandwich shop) I had lying around and the XM-L led on top (with thin spacer under the board to get correct height) with some thermal glue. And there you go, a 2A XM-L capsule for a longbow. Unscrew the old engine, screw in the new engine and the Longbow is reborn.

PS: Its actually a quite easy build if you havent done this sort of thing before, as long as you have some idea of how to solder and are handy with tools.

Wolfy thanks for the info. My original longbow capsule died. I think it was because I was using it with rechargable CR123A batteries that run at 3.6v each. Therfore my old capsule has already been cleaned out but I might take your advice and get a new one from the sandwich shop anyway. I assume using the 2 x GD1000 means you double the Amps out to the LED therefore the led burns brighter??? How long burn time would you get with your setup like this? Could I literally run 1 driver and get double burn time?
I see deal extreme sells 13mm reflectors - is there any particular one that is best. I have the standard optics at this stage? XM-L leds?? I did a search but cannot come up with a place to buy?? Any ideas? Thanks for your help.

At 2A and a single 17670, the best I can hope for is around 45min run time, so although it puts out a lot of light the run time is well under an hour. Also the GD1000 driver is single mode, so on or off. At 2A the XM-L will give about 670 emmiter lumens.

Yes using a single GD1000 will effectively double the run time and almost halve the output, and yes the GDseries was designed to easily stack so as to multiply the current. You can also get them in other currents like a GD750 say for 750mA and stack them for 1.5A for example. Also there is the GDuP driver (in 700mA and 1.2A versions) which also give multiple modes. If you run it at 1A (or up to 1.5A), you may want to consider the XP-G, it will probably work better with the optic too. An XM-L will provide up to 380 emmitter lumens at 1A, the XP-G R5 will provide almost 350 emitter lumens, and the XP-G should tend to give better throw than the XM-L both at 1A.

For the LEDs themselves and other bits, you might want to take a look at Cutter Electronics, they are an Australian supplier that are well known on CPF and sell lots of CREE LEDs on various bases. As for reflector, you may have to try a couple, I am using the reflector which was an option supplied with the Longbow Mini, but I suspect there may be a better reflector to use out there. So give the deal extreme one a try, you never know, and show us the results if you do.

You might consider an XP-G at 1.2A (using the GDuP driver) should provide almost 390 emitter lumens, for easily an hour on a good 17670 on high, but give longer run times by dropping to a lower mode if high isnt needed. That should be a nice balance between runtimes and power output if run time is important to you.

PS: The GD series and the GDuP only run up to 5.5v so using two RCR123 will most likely kill the driver. A single 17670 LiIon battery fits in the same space as two CR123 and should provide slightly better capacity than two RCR123 batteries.

PPS: The standard reflector/optic in the Longbow Mini has a ~17.5mm outer diameter and ~10.5mm height. If you dont shim the LED in the capsule (so that it sits lower) you could use a deeper reflector. So possible one of the McR16 reflectors or the IMS17 at the Sandwich shop may be options also. Cutter also may have a XP-G specific optic that may fit.

Thanks again, looked up Cutter Electronics and they have what I need. Is there a way to trigger the different modes on a GDuP driver when using a twisty tail cap?? The multiple modes are not essential for me. On off is simple and easy. Thanks for the tip with the 17670. Looks like the go. I probably need a max runtime of approx 1.5 hours so may even go as low as 700mA. It looks the XM-L still puts out over 200 lumens at this current and in a very dark underwater cave - 200 lumens is heaps. I will get a few reflectors and give them a go. Will post some photos when done.

The GDuP changes mode on a quick off-on switching, so simply twisting the tail off then on quickly should do the trick.

To get an approximation of the max possible runtime isnt to hard, so lets try a longbow with XM-L and GD1000 driver using a 17670/1600mAh battery. First we need to know the power used by the LED, which is Vf=3v at 1A according to the XM-L data sheet. So power would be;
> P=V x I = 3x1 = 3W
Now divide the LED wattage by the source nominal voltage, so for a single 17670 is 3.7v;
> Source current draw = LEDpower / sourceVoltage = 3/3.7 = 810mA
As the driver isnt perfect it actually will draw more current, with the GD1000 efficiency is listed as (85-93%) so average to 90% will give us a realistic current draw;
> realCurrent = idealCurrent/efficiency = 810/0.9 = 900mA
Now to get max possible realistic runtime, divide the battery capacity by current drawn;
> runtime = battCapacity/realCurrent = 1600/900 =1hrs45min

So with a XM-L T6 at 1A, you should get and output up to 380 emitter lumens with best run time of 1hrs45min on a 17670 1600mAh battery. To be safe you will probably get about 1hr30min and beyond that is possible, one reason is because LiIon batteries tend to reach rated capacity at low draw currents and less likely the closer it gets to the batteries max rated current output. At 750mA you should be able to get 280 emitter lumens and best runtime of 2hrs17min, so you should easily get at least 2hrs.

Also I mentioned emitter lumens, the light coming out the front (OTF) will be less, so at 1A you will probably get around 300 lumens OTF more realistically, and at 750mA probably around 200lumens. This will vary depending on if you use a glass, plastic or coated glass lens, quality of reflector and quality of optic used.

Hope that helps while you try figure out your best setup. Look forward to seeing the results.