# Dual XML sled build



## brent878 (Apr 17, 2007)

I am starting my dual XML build. Going to use 2 xml, h6flex, and a 14.8v 5200mah battery.

Here is where I am at so far. Still waiting on parts, finally got my h6flex that I was going to start to configure when I found my battery's are dead. Both of them (14.8v) won't take a charge. So I ordered a new one but gotta wait for that to come in.

My housing I am using 2x1 alum square tubing and 1.5" C channel for the sled. The heat sink is some raid heat sink I am going to cut down. Using a kill switch off my dirt bike as the switch.

Couple of questions. How does the status light on the h6flex work? I ordered some 5mm LED's to use as the status light but don't know if I need a resitor for the 14.8v battery. I have used bflex's but never used the status LED as my housing's didn't have room for it. And is the status LED on when ever the light is on? Or only when it gets low?

Also thinking about painting the housing. Is there better paint to use for this. I was thinking of a flat or satin white but didn't know if certain ones would be better for alum or for heat transfer.


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## brent878 (Apr 17, 2007)

Here is the progress so far:


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## uncle_bob (Jul 26, 2010)

This should answer your questions on how to install and configure the status led on your H6flex.
http://www.taskled.com/leds/h6flexuni_v2.00.pdf


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## emu26 (Jun 23, 2008)

brent, if you have access to a file or a hacksaw I would consider cutting / filing small grooves front to back, on the surface of the outer housing, this will greatly increase surface area and the ability of this compact lights to deal with the heat from xml's driven near capacity.


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## brent878 (Apr 17, 2007)

emu26 said:


> brent, if you have access to a file or a hacksaw I would consider cutting / filing small grooves front to back, on the surface of the outer housing, this will greatly increase surface area and the ability of this compact lights to deal with the heat from xml's driven near capacity.


This is the heat sink I will be using. I am going to cut it to size and it will be screwed to the bottom the light. I haven't caculated it out but I think it will be enough, other wise I can put more heat sinks on the mount.


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## mattthemuppet (Jul 16, 2004)

I'd still think about doing what emu suggested because every time you add a thermal junction (you already have 2 - between LED star and sled and between sled and housing) your thermal transfer efficiency drops, even though the heat sink may add a large area. It'll also make the light a little lighter which is always a plus


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## brad72 (Jun 12, 2009)

Looking very nice Brent. She's going to punch out a good amount of light.


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## emu26 (Jun 23, 2008)

Hey Brent, any reason you are putting that on the bottom and not the top? When you are standing still, and this will only be relevant where you aren't moving, that heatsink will cool faster when the air is allowed to rise up off the fins, not rise up into the fins.

Don't forget to use thermal grease or adhesive


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## brent878 (Apr 17, 2007)

mattthemuppet said:


> I'd still think about doing what emu suggested because every time you add a thermal junction (you already have 2 - between LED star and sled and between sled and housing) your thermal transfer efficiency drops, even though the heat sink may add a large area. It'll also make the light a little lighter which is always a plus


You are correct that it would be better heat wise to use the housings as a heat sink but I don't think I could make it good enough to not use an additional heatsink and since I have to use one anyways I rather not hack up the housing. With my amiable tools I don't think I could cut groves into the housing with out it looking like crap. As far as weight goes I can shave down the heat sink if I feel its too big. It is pretty heavy but I haven't cut it down yet. After I get it to size i will weigh it and see if I need to put it on a diet. But not too concerned with weight, its like 2x2x1. I'll show you a pic of the new housing next to my old lights i built that it is replacing.





















brad72 said:


> Looking very nice Brent. She's going to punch out a good amount of light.


thanks. hopefully it will be a good beam pattern. They were out of stock on the other lenes I wanted to try so I am stuck with only one choice.



emu26 said:


> Hey Brent, any reason you are putting that on the bottom and not the top? When you are standing still, and this will only be relevant where you aren't moving, that heatsink will cool faster when the air is allowed to rise up off the fins, not rise up into the fins.
> 
> Don't forget to use thermal grease or adhesive


The reason is because I am planning mounting the light to the steering stem under the stem so there will be no room for the heatsink between the stem and light body. If it comes out the way it does in my head you won't even see the heat sink unless you flip the bike over or are looking at the light from the ground.

Here is where I would like it to end up.


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## uncle_bob (Jul 26, 2010)

Heat isn't too bad with this light. Set at 50C degrees the driver takes approx 5-6 minutes to reduce amps at 18C ambient on my light, which is not too dissimilar to the one I finished today.


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## scar (Jun 2, 2005)

Looks great! :thumbsup:


***


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## brent878 (Apr 17, 2007)

uncle_bob said:


> Heat isn't too bad with this light. Set at 50C degrees the driver takes approx 5-6 minutes to reduce amps at 18C ambient on my light, which is not too dissimilar to the one I finished today.


Ya that is about what mine should look like. Except the heat sink will be on the bottom and it will be mounted under the bars. Did you have any problems or things you wish you did differently?


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## uncle_bob (Jul 26, 2010)

brent878 said:


> Ya that is about what mine should look like. Except the heat sink will be on the bottom and it will be mounted under the bars. Did you have any problems or things you wish you did differently?


This is the second time I have built this light, the first time I used reflectors from DX and was not very happy with the beam and it originally didn't have the hood over the light output. So I took the old light to pieces and cut another body with hood, used the old sled and put in some Regina reflectors and the end result is much more pleasing.

I also used some M2 cap screws too hold the heat sink and mount-sink to the body. I am not convinced that J-B weld would hold on its own.

Good luck with yours brent


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## brent878 (Apr 17, 2007)

Here are some progress pics. Going to start painting today and hopefully finish up the wiring once the paint is finished. Hoping to test it out tomorrow night. Fingers crossed.


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## scar (Jun 2, 2005)

*Nice idea*

digging the stem mount :thumbsup:

wondering how effective the heatsink will be on the bottom as heat rises?

***


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## brent878 (Apr 17, 2007)

scar said:


> digging the stem mount :thumbsup:
> 
> wondering how effective the heatsink will be on the bottom as heat rises?
> 
> ***


I don't think the heatsink will be a problem on the bottom. The light will either be off or on low when I am stopped so it shouldn't be generating too much heat. I think.

Does anyone know what voltage numbers I should be using for voltage med, low, and cuttoff warnings on the h6flex? I am using a 14.8v battery.


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## mattthemuppet (Jul 16, 2004)

the *flex buck drivers, like the h6flex, come programmed as standard with the values for 4S li-ion packs, which should be detailed in the menu section of the manual. As a rough rule of thumb, Vcut is 3V x no. cells, Vlow is ~3.2V x no. cells and Vmed is ~3.6V x no. of cells.

Why are you using a 4S pack, is it one that you already have? If you're building it from scratch, a 3S pack would make more sense.


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## brent878 (Apr 17, 2007)

mattthemuppet said:


> the *flex buck drivers, like the h6flex, come programmed as standard with the values for 4S li-ion packs, which should be detailed in the menu section of the manual. As a rough rule of thumb, Vcut is 3V x no. cells, Vlow is ~3.2V x no. cells and Vmed is ~3.6V x no. of cells.
> 
> Why are you using a 4S pack, is it one that you already have? If you're building it from scratch, a 3S pack would make more sense.


Cool thanks for the guide lines. My old lights use a 14.8v battery and I was planning on using that until I tested out my old batteries and found them to be dead. I still stuck with the 14.8v battery so I could still use my old lights if I want to. That is the only reason I went with a 4S pack instead of a 3S pack.


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## brent878 (Apr 17, 2007)

Here are some pics. After painting and putting everything I found out that I made my stem mount alittle too short. Its fine until you start to angle the light down and then the heat sink hits the head tube. So I gotta make another one of those. Also I left the heat sink full size. I really want cut it down but don't know how much I need for heat so I am going to test it out like this and see how it does. After I found the stem mount too small I kinda rushed the paint knowing that I am going to have to redo it again.

Oh another thing, I painted the back of the optics with blue glow in the dark paint. I am not sure how that affects the light output but i'll find out I guess. My whole frame glows in the dark so I thought it would be a cool idea. I also setup my status LED to shine on the head tube to charge it but the light is so close to the head tube I don't think its goign to work.


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## mattthemuppet (Jul 16, 2004)

no worries  Makes sense to keep your existing batteries and it won't really make much difference over a 3S pack.

The light looks really good, blends in very well too. Having it under the bar should help avoid blinding yourself when you go over logs and the like (a problem I have). Did you figure out the angle of the mount first or can you bend it slightly to adjust it? Having a GoPro style mount that you can undo, adjust and cinch up again would be super sweet.

Oh, and don't forget to put some thermal compound between the light body and the mount, otherwise you'll lose out on all that surface area


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## brent878 (Apr 17, 2007)

mattthemuppet said:


> no worries  Makes sense to keep your existing batteries and it won't really make much difference over a 3S pack.
> 
> The light looks really good, blends in very well too. Having it under the bar should help avoid blinding yourself when you go over logs and the like (a problem I have). Did you figure out the angle of the mount first or can you bend it slightly to adjust it? Having a GoPro style mount that you can undo, adjust and cinch up again would be super sweet.
> 
> Oh, and don't forget to put some thermal compound between the light body and the mount, otherwise you'll lose out on all that surface area


I can bend to adjust up until the point where the back of the light touches the frame. I haven't tested it out yet so I don't know what is the correct angle. I think its pointed high right now but we'll find out tonight.

Thermal compound is applied to the sled, heatsink, and mount. But the mount doesn't sit flush against the light body right now becuase I bent it too much. But the new longer mount will sit flush when I am done with it. Just gotta work all the bugs out for now.


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## brent878 (Apr 17, 2007)

Ok tested the light out last night. Beam pattern is pretty bad, painting the optics wasn't the best idea. Kinda turned it into a super flood with not much of a hot spot. The light is so bright that it was ridable and was about the same brightness as my P7 light just light everywhere though. Couldn't tell if I was pointed at the right angle since there was no real hotspot to judge where the center of the beam is pointing, haha.

I was having one problem that I haven't figured out yet. About 3 times during the night the light would flash once and remained turned off no matter how many times I hit the button. The only fix would be to unplug the battery and plug it back in and it would work normally. I noticed that this would occur when I was pressing the button. I would press to turn on or change mode and the light would flash and turn off and only fix would be to unplugg battery. I am running it on UIB mode in threemode.

Also my white brake cable was in the beam pattern and felt like someone had a little flash light shining at my face all night. Just gotta reroute the cable and problem should be solved.


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## brent878 (Apr 17, 2007)

Ok figured out why the light is turning off. If I go to high (3000mah) from off it trips the pcb board on the battery. George (taskled) suggested wiring in a cap to the battery to take some of the inital load off. I ordered a cap and waiting for it to come in. It only happens if I turn the light off in high wait about ten seconds and turn it and it flashes once and trips the pcb board. The only way to get the light back on is to unplug battery. Only happens if I start on high, med (L3) and low (L2) are fine.

This is the cap I ordered: 1000µF, 25V

Digi-Key - P12379-ND (Manufacturer - EEU-FM1E102)

Has anyone else run into this problem? Will the cap solve the problem?


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## mattthemuppet (Jul 16, 2004)

no idea! First time I've heard of it. Is the PCB in the battery replaceable? Getting one with a higher discharge limit (5A?) and, even better, internal balance ports, would be a good long term solution. They're not terribly expensive ($20?) either. Try the cap first though.


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## OldMTBfreak (Apr 8, 2006)

When I was using Halogen bulbs, the initial current surge would trip the overcurrent in the battery protector PCB. A 100uf cap at the connector in the lighthead solved that problem.


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## brent878 (Apr 17, 2007)

OldMTBfreak said:


> When I was using Halogen bulbs, the initial current surge would trip the overcurrent in the battery protector PCB. A 100uf cap at the connector in the lighthead solved that problem.


Cool that's what I want to hear. Did you wire your to your battery or inside the light? I am thinking inside the light would be better so it will work on any battery I hook up to it but I don't think I have room inside the light for the cap. But I only have one working battery left so its not a big deal to have it on the battery.


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## brent878 (Apr 17, 2007)

Here is another one I built. 7.4v battery, Lflex driver, 2x XML


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## mitchellluke (Jun 25, 2011)

Nice light Brent! Have you thought about vibrations on the stem mount causing fatigue and snapping? What is the weight? Curious to see if this is a problem


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## brent878 (Apr 17, 2007)

mitchellluke said:


> Nice light Brent! Have you thought about vibrations on the stem mount causing fatigue and snapping? What is the weight? Curious to see if this is a problem


I have not weighed the lights but I should. Are you talking about fatigue on the stem itself? I am not too worried about that. Once you pre-load the headset bearings and tighten down the stem the light is solid. I was trying to bend the mount to adjust the angle while it was on the bike and I couldn't do it. I can't even rotate it side to side. I can't imagine it putting any more stress than the stem and handle bars even though its a smaller surface area on the stem.

Does anyone else think this could be a problem over long periods of time (a few years)? Seems so solid that I think vibrations wouldn't be a factor. But I have no scientific proof other than feeling how solid of a mount and I can't phsyically move it.

Now what I didn't take into consideration is a big crash on the light. I am not sure which would give first, the light or the stem. I think it would have to depend on the angle of the hit. But with the light being mounted under the bars/stem I am hoping that it would not be the first to hit something in a crash. And no way to test other than taking a hammer to a mounted light and seeing what gives first or to do a nasty crash and see if it holds up. Eitehr one is not something I am willing to test, haha.


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## mattthemuppet (Jul 16, 2004)

I doubt you'll have a problem with fatigue. It's on a sprung part of the bike and the material seems plenty thick enough. Time will tell, but I wouldn't worry about it.

How do you deal with adjusting the angle of the light for different terrain though? I often fiddle with my bar light depending on how open the trail is - pointing further up for fast, smooth trails, pointing further down for slow, rocky ones.


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## muzzanic (Apr 28, 2009)

If you come off the bike & the front wheel/ handle bars spin around you will damage the fram for sure, There is no way I would run the risk.


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## mitchellluke (Jun 25, 2011)

You could bend the mount 90ish degrees up and make a mount between the head stem and bars.


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## brent878 (Apr 17, 2007)

mattthemuppet said:


> How do you deal with adjusting the angle of the light for different terrain though? I often fiddle with my bar light depending on how open the trail is - pointing further up for fast, smooth trails, pointing further down for slow, rocky ones.


There is no adjusting the angle once its on the bike. To adjust the angle you have to put the mount in a vice and bend it. We adjusted the angle when we mounted it. I never adjust my light once I have it where I want it. If you adjust your light often then this mount isn't going to be good.



muzzanic said:


> If you come off the bike & the front wheel/ handle bars spin around you will damage the fram for sure, There is no way I would run the risk.


If you spin the bars all the way around the light can hit the frame. I think on all my past bikes I could never spin the bars around with out something hitting the frame. Usually a brake lever or something. Never had frame damage other than chipped paint. And I would think that if it were to hit hard the mount would rotate on the stem before denting a top tube.


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## brent878 (Apr 17, 2007)

Light number 3
7.4v battery, Lflex driver, 2x XML


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