# 35mm 7up XML board!



## kwarwick (Jun 12, 2004)

7 x CREE XM-L U2 on round PCB by LED-TECH.de

Got me thinking about how this might work out as a replacement board in one of my Troutie 7up lights with Polymer Optics. The Maxflex driver will limit the drive current to 1330-1400ma but still this would produce a lot of light and probably pretty efficiently given the XMLs would not be driven very hard. Should put out more than 7 XPGs driven at the same current, but is the small gain worth even bothering?


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## troutie-mtb (Sep 20, 2007)

according to my calcs that should be around 3640 lumens at 1400 ma drive 

and if you had a housing that could handle full whack 6000 lumens

but the pcb size says 35 mm so will it fit the optic.


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## kwarwick (Jun 12, 2004)

troutie-mtb said:


> but the pcb size says 35 mm so will it fit the optic.


The PCB is smaller, but is designed for the same optics as Cutter board. I actually have this same PCB with XPGs and no problem fitting Khatod or Polymer optics. One minor issue is the holes for the wires are not in the same place as Cutter board some work would need to be done to fit your 7up housing.

Now driven at full current in an appropriate housing? Darkness Dominator^2!


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## Toaster79 (Apr 5, 2010)

Are there any decent 7up optics out yet in this size format? With polymer optics you'll get hell of a lot of flood, and you won't notice the gain in light output, but you might be disappointed with visually lower output even though the numbers speak in other directions.


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## kwarwick (Jun 12, 2004)

Toaster79 said:


> Are there any decent 7up optics out yet in this size format? With polymer optics you'll get hell of a lot of flood, and you won't notice the gain in light output, but you might be disappointed with visually lower output even though the numbers speak in other directions.


Actually I found the Polymer Optics to be a big improvement over Khatod (at least when used with XPG)... a lot less flood, more spot like. I would liken the beam produced to a larger version of the Carclo 20mm optics. True that probably no optics of this small are going to get the most out of the LEDs and I have no idea how well the Polymer Optics would work with the larger die size of XML.


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## Toaster79 (Apr 5, 2010)

I've tried those single hex shaped narrow polymers with XML, and believe me, you don't want to see the beam shots.


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## kwarwick (Jun 12, 2004)

Toaster79 said:


> I've tried those single hex shaped narrow polymers with XML, and believe me, you don't want to see the beam shots.


That's disappointing to hear. :cryin: I guess the optic wasn't really designed for larger die size of XML. Does Polymer list it as compatible with XML? The 7up optics are listed officially as for XPE... not even XPG .


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## Goldigger (Nov 6, 2009)

That would be some serious heat at full power..
I'm still trying to find these PCB's with xm-l's and some suitable optics


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## troutie-mtb (Sep 20, 2007)

Goldigger said:


> That would be some serious heat at full power..
> I'm still trying to find these PCB's with xm-l's and some suitable optics


i dont think you would need any optic for that beast.


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## brad72 (Jun 12, 2009)

troutie-mtb said:


> i dont think you would need any optic for that beast.


That thing is rated at 10,000 lumen so wear your sunglasses


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## rschultz101 (Oct 5, 2009)

couple of thoughts,... 
- cost, it adds up,... 
- tons of heat, all the leds on one substrate, and looking at the layout, not the best
probably sufficient 
- optics, limited, and it's all or nothing,
that said, I'd rather have 2x3 with 2 optics
- size, 35mm + 39mm optics, + front glass, + O-ring,... it's a 50mm
- driver , needs a boost,.... and 4S battery,..
- watts of heat, ok, it's going to be a winter or downhill only
- weight ? ok heatsink is minimal, how about the battery, how many cells do you need ?
for medium / full, ?
- can you afford the new battery and charger ? since it ain't going to run of your old 4cell 2S
-----
options, get an Lupine upgrade kit , decent layout, option for xml and xpg mix, decent optics,
less headaches,...

oh, 
Happy New Year !
Bonne Anne!
Sretna Nova Godina!
Frohes Neues Jahr!
cheers, Rob
Auf der Alm, da gibts a Sünd, nen MTB Reifenprofil auf dem Weg,...


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## kwarwick (Jun 12, 2004)

The thought of 3600-3900lm was too much to resist so I ordered one of the 7up XML boards from led-tech.de today (they had them on "Daytrade" so I managed to snag one for €43.74 EUR all in).

Since I'll be driving these at 1300ma the Maxflex's should have a pretty easy job of boasting my 4S lipo packs to meet the lower total voltage requirements of 7 XMLs (vf=3.05 * 7 = 21.35V) vs 7 XPGs (vf=3.45 * 7 = 24.15V). The Maxflex will run cooler and the LED will be putting out more lumens for the same amount of current so the LEDs should run cooler also.

Seems almost too good to be true? Stay tuned...


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## rob1111 (Jun 16, 2009)

If you are interessted, here is the thread from the german forum regarding the 7xml:

click me

I am running the board at 2A (so about 43W) from a 4s battery. The housing is REALLY hot within 1min30s. 
My housing and stuff:


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## kwarwick (Jun 12, 2004)

Rob1111, thanks for that link... lots of good information there! Glad to see I'm not wasting my time with this upgrade. Although my German is not good, Google translate comes to the rescue in most cases. :thumbsup:

I also took a look at rad-ass.de and found some beam shots:

www.rad-ass.de: Vergleichsbilder

The last two pictures confirm what I suspected, same or better throw with more flood which makes sense given the large die size of XML.


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## kwarwick (Jun 12, 2004)

*Built her up*

The 7 up xml board arrived yesterday and I spent the night upgrading my Troutie light with this monster.

I haven't had a chance to take it on a ride, but preliminary tests are not disappointing... it is definitely the brightest light I have built so far. Not as floody as I expected... the Polymer Optics create a squarish hotspot and overall do a admirable job given they were never designed with XML in mind.

I noted that power consumption on high dropped approximately 2 watts overall (28.8w vs 31.0w) when compared to 7 up XPG which I assume is due to lower vf of XMLs.


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## brad72 (Jun 12, 2009)

Made that 7 up board looks beautiful and l like the polymer optics. I assume they are better than the Kathod 7up.


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## xyz-saft (Sep 23, 2010)

Really nice 7-up board, and that housing is a pice of art!
What current are you running at high? Not 3A I guess...

A beamshot or two would be nice.


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## kwarwick (Jun 12, 2004)

brad72 said:


> Made that 7 up board looks beautiful and l like the polymer optics. I assume they are better than the Kathod 7up.


To be sure Polymer is quite a bit better than the Khatod at sending the light forward without that halo effect. I've tested this lens with 7up XPE XPG and now XML and with each increase in LED die size the hot spot gets larger, but still quite respectable given the small size of these optics.


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## kwarwick (Jun 12, 2004)

xyz-saft said:


> Really nice 7-up board, and that housing is a pice of art!
> What current are you running at high? Not 3A I guess...
> 
> A beamshot or two would be nice.


I wish I could take credit for the housing but that has to go to Mr. Troutie. This housing has probably been eclipsed by his new 3 XML Darkness Dominator but I think with this 7 XML board the balanced is shifted again. 

You're right, definitely not running at 3A! Since this Troutie light was designed for Maxflex driver, that's what I'm using, set at the highest current table of 1400ma. I have the thermal protection set to 70c and indoors it will throttle the current after a few minutes on full. With proper airflow this hasn't been an issue.

I'll see what I can do on beam shots, but the beam shots I referenced on rad-ass website (www.rad-ass.de: Vergleichsbilder) seem to be pretty accurate.


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## kwarwick (Jun 12, 2004)

*7up XPG vs. 7up XML beamshots*

Since I'm too lazy to do beamshots at the moment, here are two from the forums of germain mtb-news.de site. Not a hard decision which is better I'd say.

First is 7 XPG (driven at 1000ma) with Khatod optics

Second is 7 XML (driven at 1350ma) with Polymer optics


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## troutie-mtb (Sep 20, 2007)

looks pretty good 
be good to see one at full chat as the xmls don't come alive till after 1.5 amps


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## Goldigger (Nov 6, 2009)

Can always put the new b2flex in when George releases them..
See what you can get away with..2amps maybe 2.5 when on the move..?


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## kwarwick (Jun 12, 2004)

Goldigger said:


> Can always put the new b2flex in when George releases them..
> See what you can get away with..2amps maybe 2.5 when on the move..?


Oh believe me I thought about that  but the problem would be the battery to drive it since the b2flex is a buck converter so input voltage needs to be higher than output.

7 XMLs will need up to 23.45 volts at 3000mA and the b2flex needs some additional head room to stay in regulation so probably 26 volts minimum would be needed. So we're looking at a 7S1P battery .

A 6 XML board would be a much easier proposition as you could run 3S2P wiring for the LEDs and drive them at 6000mA, something a H6flex could handle with a much more common 4S1P battery, but H6flex wouldn't fit this housing.


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## Goldigger (Nov 6, 2009)

kwarwick said:


> Oh believe me I thought about that  but the problem would be the battery to drive it since the b2flex is a buck converter so input voltage needs to be higher than output.
> 
> 7 XMLs will need up to 23.45 volts at 3000mA and the b2flex needs some additional head room to stay in regulation so probably 26 volts minimum would be needed. So we're looking at a 7S1P battery .
> 
> A 6 XML board would be a much easier proposition as you could run 3S2P wiring for the LEDs and drive them at 6000mA, something a H6flex could handle with a much more common 4S1P battery, but H6flex wouldn't fit this housing.


I didn't even look at the technical details..
H6flex is only good for 20v so smack on the limit for 6 leds


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## OldAusDigger (Apr 8, 2008)

troutie-mtb said:


> looks pretty good
> be good to see one at full chat as the xmls don't come alive till after 1.5 amps


Troutie, is there any chance you could machine up a supplementary heat sink for kwarwick (or anyone else using this housing) that could be easily attached to allow this type of combo to run more current?


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## troutie-mtb (Sep 20, 2007)

OldAusDigger said:


> Troutie, is there any chance you could machine up a supplementary heat sink for kwarwick (or anyone else using this housing) that could be easily attached to allow this type of combo to run more current?


Probably be easier to design a new housing than an add on 
would need to be a serious heatsink and radiator to keep that beast cool 
particularly the centre led


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## Goldigger (Nov 6, 2009)

Can always use the old housing, and use the light for a fitness program...
Pedal as fast as you can so that the thermal protection doesn't kick in..once thats to easy change the thermal protection to the next level down..


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## brad72 (Jun 12, 2009)

I have been looking at a 7 up housing for the XML If I allow 2in² per watt I would need about 140in² of heatsinking. That's twice as much as my triple xml light. I have some ideas on how to achieve it whilst still looking nice but I need more tinkering time in cad. 

I am also thinking given the size of the pcb the core and contact face of the heatsink should perhaps be copper to get that heat away faster. 

Perhaps GD's idea of pedalling as fast as you can is simpler.


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## gticlay (Dec 13, 2007)

George just needs to make some sort of driver with a same-diameter heat sensor you sandwich between the lightboard and body that regulates current based on temperature. Stop for a second? No problem. Bombing down fast singletrack? It bumps the current up since things are getting cooled well.


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## OldAusDigger (Apr 8, 2008)

troutie-mtb said:


> Probably be easier to design a new housing than an add on
> would need to be a serious heatsink and radiator to keep that beast cool
> particularly the centre led


You know you want to build it - maybe even a twin 7 up XML :thumbsup:

It's been a long time since you've let your hooligan side surface  . There would be a lot of people on this forum who'd love to see the old Troutie make a comeback to assault the undisputed heavyweight lumen crown!

Forgive me for slightly taking the thread of topic - just wanted to throw that out there


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## kwarwick (Jun 12, 2004)

Besides the housing, the other big issue standing in the way of 7 XMLs being driven at 3000mA is the driver!

I've been through all the calculations and permutations and I don't know of any single TaskLED driver that is up to the job. I know George says that boost drivers are harder to do with higher currents, but I think we need to keep bugging him to do a hyper MaxFlex driver.


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## troutie-mtb (Sep 20, 2007)

OldAusDigger said:


> You know you want to build it - maybe even a twin 7 up XML :thumbsup:
> 
> It's been a long time since you've let your hooligan side surface  . There would be a lot of people on this forum who'd love to see the old Troutie make a comeback to assault the undisputed heavyweight lumen crown!
> 
> Forgive me for slightly taking the thread of topic - just wanted to throw that out there


Ha Ha old Devils advocate there but yes I must admit to wanting to do another crazy 
light


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## [jsl] (Sep 20, 2007)

kwarwick said:


> Besides the housing, the other big issue standing in the way of 7 XMLs being driven at 3000mA is the driver!
> 
> I've been through all the calculations and permutations and I don't know of any single TaskLED driver that is up to the job. I know George says that boost drivers are harder to do with higher currents, but I think we need to keep bugging him to do a hyper MaxFlex driver.


How about running the leds in ( 2P + 2P + 3P )S configuration with h6Flex programmed for 6A max? OK, the 3P set would not get full 3A per led, like in the two 2P sets, but still, I don't think the setup would be exactly dim


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## kwarwick (Jun 12, 2004)

[jsl] said:


> How about running the leds in ( 2P + 2P + 3P )S configuration with h6Flex programmed for 6A max? OK, the 3P set would not get full 3A per led, like in the two 2P sets, but still, I don't think the setup would be exactly dim


Interesting idea. I was also thinking of 2P+2P+2P driven with H6flex and coming up with some other way to drive the center LED or just leave it disconnected. Biggest issue though, is H6flex will not fit in the space inside this host. It has room for MaxFlex and perhaps it could do B3flex, but H6flex is too large diameter wise.

At this point I'm fine with the compromises needed to run 7up XML in the Troutie housing. Brightness and efficiency with manageable heat actually makes for a pretty good solution. Lupine is doing pretty much the same thing in the current version of the Betty - 7up XML putting out 2600 lumens. I think trying to crank 7000-8000 lumens out of a light this size is of questionable value without optics that can better control the beam. IMHO, better to have two lights of half the lumens each that can be aimed independently where needed.


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## gticlay (Dec 13, 2007)

How about a housing that uses one of those waterproof fans like (can't remember member just now) made with his wall-e and super quad lights. Man that guy proto'd up some magic stuff.


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## emu26 (Jun 23, 2008)

brad72 said:


> I have been looking at a 7 up housing for the XML If I allow 2in² per watt I would need about 140in² of heatsinking. That's twice as much as my triple xml light. I have some ideas on how to achieve it whilst still looking nice but I need more tinkering time in cad.
> 
> I am also thinking given the size of the pcb the core and contact face of the heatsink should perhaps be copper to get that heat away faster.
> 
> Perhaps GD's idea of pedalling as fast as you can is simpler.


OK Brad, so here's my thoughts on how you keep this cool.

You could run a fan assisted like similar to cosmoworks quad sst but meeh, that's been done and doesn't really look that innovative (  ) or you could try a much more elegant design of this concept

here (I'll try to attach the pic as well

Clearly that was done by a fitter and turner, not a machinist.

I'm thinking an air intake scoop across the bottom front edge of the light that is just a series of holes drilled through the base of the light all the way to the bottom of the heatsink "wall". This "wall" needs to be thicker than usual say around 5 mm. Now for the tricky bit. Drill a series of holes down from the top of the light through the guts of the firewall so that they link up with the "Pipes" coming in from the bottom front.

As you're riding along air is forced in the bottom, up through the heatsink itself, and vented out the top of the light. Only real problem, apart from making sure the "pipes" line up is mud which would block the holes and then be a pita to clean out. Rain would be your friend because you have not compromised either the LED nor driver cavities at all so moisture isn't going to short anything out AND the pipes then become water cooled. Of course you could then also have your normal "finning" on the light but I don't think you'd need the 2" / watt.

Eagerly sitting back now to see what you come up with


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## mattthemuppet (Jul 16, 2004)

you'd have to be going some serious speed to overcome the boundary layer drag in those small pipes. Motorcycle fast yes, mtb fast unlikely.

Now a watercooled light would be pretty sweet, but for the amount of weight you're adding you might as well just add more surface area instead


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## brad72 (Jun 12, 2009)

One of my old idea's was to drop a make a traditional housing with but with a small pocket to drop a pellet of dry ice into. You would get some serious cooling like a peltier cooler but without the need of a massive battery to power it.

I fiddled around on cad last night and a the most surface area I can get out of a housing 80 x 50mm is about 77in² so if we want to run at 2.8-3A the housing is going to be pretty big, especially since the heat is so concentrated.

Water cooling is not so silly though. The cranks could run a small belt driven pump as the cooling the light is going to be most important what travel on the flat or uphill. Alternatively a low voltage pump could be used. The pump could either be an impeller style, peristaltic, or a centrifugal, getting the flow rate by gearing it faster than the cranks of supplied voltage. A small alloy radiator could be made and mounted under the bar stem to keep it out of way. Fill the system with solution of water and ethylene glycol and bam, you've got a cool looking light (pardon the pun)


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## emu26 (Jun 23, 2008)

mattthemuppet said:


> you'd have to be going some serious speed to overcome the boundary layer drag in those small pipes. Motorcycle fast yes, mtb fast unlikely.
> 
> Now a watercooled light would be pretty sweet, but for the amount of weight you're adding you might as well just add more surface area instead


Yes, but you'd have to be going pretty quick to NEED the amount of light a 7 up XMl would put out, like motorbike fast


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## gticlay (Dec 13, 2007)

troutie-mtb said:


> Ha Ha old Devils advocate there but yes I must admit to wanting to do another crazy
> light


How about a 10-up with some sort of mix of the XT-E and XPG? I rather like those little square "stars" you use on some of your builds.


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## mattthemuppet (Jul 16, 2004)

brad72 said:


> One of my old idea's was to drop a make a traditional housing with but with a small pocket to drop a pellet of dry ice into. You would get some serious cooling like a peltier cooler but without the need of a massive battery to power it.
> 
> I fiddled around on cad last night and a the most surface area I can get out of a housing 80 x 50mm is about 77in² so if we want to run at 2.8-3A the housing is going to be pretty big, especially since the heat is so concentrated.
> 
> Water cooling is not so silly though. The cranks could run a small belt driven pump as the cooling the light is going to be most important what travel on the flat or uphill. Alternatively a low voltage pump could be used. The pump could either be an impeller style, peristaltic, or a centrifugal, getting the flow rate by gearing it faster than the cranks of supplied voltage. A small alloy radiator could be made and mounted under the bar stem to keep it out of way. Fill the system with solution of water and ethylene glycol and bam, you've got a cool looking light (pardon the pun)


the downside of any crank driven waterpump (other than parasitic losses) is that it will be turning slowest when airflow is lowest. Then you'd need some kind of thermostat controlled fan assistance  I think the main advantage of water cooling in any cooling situation is one of packaging, in that it allows you to move the cooler away from the heat source to the most advantageous spot. I don't think that that's really the problem with bike lights.

Short of fan assistance, I think that bike lights will naturally top out at ~30W, with more light coming from increased LED efficiency. Besides, who'd want to carry around the battery needed to power a 7up XM-L at 3A?


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## piesoup (Feb 9, 2009)

A few years ago I seriously looked into making a water cooled light. It was going to be 6 MCEs driven at max chat. 
I abandoned it for several reasons. Firstly, the rad and pump along with all the fittings was hugely expensive. Especially if you wanted a nice small neat pump that ran off a reasonable voltage. Like Matt said, running off the crank is only usefull when you're giving it beans. It would also be in the region of 1kg for the complete light. The LEDs alone needed a huge battery. The pump was very inefficient, needing its own huge battery. 

I also looked into getting rid of the rad and looping the piping containing the coolant around the head tube so the frame drew the heat away. Looked messy!

One I haven't had time to play with is if you have a metal steerer on your forks, especially tapered, turn the whole steerer into a reservoir/heatsink. Pump could sit at the lower end of the steerer, hopefully hidden. Then just a pressure and return pipe to the light. Link the pump to a thermostatic switch so it only runs when needed. 

I think the best method is similar to what was mentioned above. Have another temp sensor on the driver. The taskled ones have temp sensing but that it mainly there to protect the FET, not the LEDs. The driver needs to be kept cool too, so sticking it to the 'firewall' is an easy solution but probably not the best. Hotter the driver, the less efficient is gets. How about sinking the driver elsewhere, but having an NTC resistor or similar on fly leads so you can position the as close as possible to the hottest LED? i.e. The centre one on a 7 up. There might be enough real estate on a h6Flex for this? 

I got a friend to make up a proto board that dims the light (using a flex driver) when you stop. Then once you move, it's back to normal control. That leaves you free to ride and not worry about remembering to turn off your 5000lms when you stop! Has more features and needs debugging.


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## troutie-mtb (Sep 20, 2007)

If the beam is any good I would like to use it in a 6 and 1 configuration 
where the centre led is on a driver of its own and you can use either 1 led or 6 leds 

imagine the surprise of the rider in front when you switch from 1 led to 6 at full whack .:devil:


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## Goldigger (Nov 6, 2009)

troutie-mtb said:


> If the beam is any good I would like to use it in a 6 and 1 configuration
> where the centre led is on a driver of its own and you can use either 1 led or 6 leds
> 
> imagine the surprise of the rider in front when you switch from 1 led to 6 at full whack .:devil:


I was talking to my mate who has two of my tripple XM-L's on the bars..said he was riding down the road with both on medium and some driver started flashing him, so he switched both onto high  :devil:

Cant we adopt cosmo's concept and fix this light to the stem cover, would need a bulkier pivot so that you can adjust the light up and down, but when i say bulkier it would need to have more contact with the light body to try and draw some heat away..
I would knock up a drawing but I'm at work so cant..

If it can pull enough heat out, you'd probably also benifit from heated bars/grips during the winter


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## piesoup (Feb 9, 2009)

Goldigger said:


> I was talking to my mate who has two of my tripple XM-L's on the bars..said he was riding down the road with both on medium and some driver started flashing him, so he switched both onto high  :devil:
> 
> Cant we adopt cosmo's concept and fix this light to the stem cover, would need a bulkier pivot so that you can adjust the light up and down, but when i say bulkier it would need to have more contact with the light body to try and draw some heat away..
> I would knock up a drawing but I'm at work so cant..
> ...


What about a heat pipe type affair wound round the stem or bars?

Looking at an XML 7up run from a maxFlex. 1300mA on each led gives you 3661lm. Without losses but that's still going to be bright!


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## Goldigger (Nov 6, 2009)

A quick google, this is what i had in mind for the stem face plate to mount the light in, instead of just having a slot on the back of the light head that fits in between the mount..
Here's roughly what the mount would look like








And how it would mount to the light head..


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## Vancbiker (May 25, 2005)

Maybe water cooling with no pump?

Thermosiphon - Wikipedia, the free encyclopedia


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## troutie-mtb (Sep 20, 2007)

seems to be a case for me to revisit the stemplate light










and if the bars are not enough to sinkaway the heat then some coolant in the bars 
just enough to move about with the normal movement of the bike thus taking the heat to the bar extremities


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## troutie-mtb (Sep 20, 2007)

Vancbiker said:


> Hitting the correct aiming angle with that seems a challenge!


Not at all as it will be a fair old flood light that one worked well and had 2 XREs on board .


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## Vancbiker (May 25, 2005)

troutie-mtb said:


> seems to be a case for me to revisit the stemplate light.


Hitting the correct aiming angle with that seems a challenge!


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## kwarwick (Jun 12, 2004)

*Copper version just released*

If anyone is interested, looks like LED-TECH recently released a copper MCPCB version of this board (its on Day Trade special today):










7 x CREE XM-L U2 on copper-round PCB by LED-TECH.de


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## C-Far (Oct 31, 2011)

what kind of battery do you guys suggest to power 1 of these?


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## Goldigger (Nov 6, 2009)

The inner lumen devil says go on buy one but at £60 roughly its not cheap..then I would need a new battery etc etc...
:-(


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## kwarwick (Jun 12, 2004)

Goldigger said:


> The inner lumen devil says go on buy one but at £60 roughly its not cheap..then I would need a new battery etc etc...
> :-(


I hear that! I already have the non-copper one and this one is calling to me for some unknown reason. 

I don't think it makes any sense when being driven at less than half power like I'm currently doing in my Troutie host, but with the right driver and a bigger housing to dissipate all that heat the copper board would definitely be the way to go.


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## Goldigger (Nov 6, 2009)

Am I correct in thinking the standard board had individually addressable LEDs?
It might be possible to use two b3flex as there nice and small..although it would need two switches..
1 b3flex to power 4 LEDs vf 13.6v +1.1v for the b3flex 14.7v 
1 b3flex to power 3 LEDs vf 10.2v +1.1v for the b3flex 11.3v

Only problem is you would need a 5s lipo/li-on 21v, which is going to be to much overhead for the 2nd b3flex, unless you run a double battery pack..which would be very bulky.
It's the 7th led that causes a problem I think..6 LEDs it would work


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## kwarwick (Jun 12, 2004)

Goldigger said:


> Am I correct in thinking the standard board had individually addressable LEDs?
> It might be possible to use two b3flex as there nice and small..although it would need two switches..
> 1 b3flex to power 4 LEDs vf 13.6v +1.1v for the b3flex 14.7v
> 1 b3flex to power 3 LEDs vf 10.2v +1.1v for the b3flex 11.3v
> ...


Hmmm... I'm not sure what you mean by too much overhead for the 2nd b3flex? I believe you can run whatever input voltage you want as long as it meets the minimum requirements as you've calculated. Generally there is no reason to have such a wide input and output difference, but I'm pretty sure it is allowed. Does the efficiency suffer when doing so, I'm not sure?

You're right though, 6 LEDs (or 8) would be a heck of a lot easier to deal with as then you could use a H6flex to drive two strings in parallel.


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## Goldigger (Nov 6, 2009)

kwarwick said:


> Hmmm... I'm not sure what you mean by too much overhead for the 2nd b3flex? I believe you can run whatever input voltage you want as long as it meets the minimum requirements as you've calculated. Generally there is no reason to have such a wide input and output difference, but I'm pretty sure it is allowed. Does the efficiency suffer when doing so, I'm not sure?
> 
> You're right though, 6 LEDs (or 8) would be a heck of a lot easier to deal with as then you could use a H6flex to drive two strings in parallel.


i always thought we needed to get the battery voltage as close to the output voltage as possible as excess voltage is wasted as heat??


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## Toaster79 (Apr 5, 2010)

Goldigger said:


> i always thought we needed to get the battery voltage as close to the output voltage as possible as excess voltage is wasted as heat??


 Only with linear regulators.


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## kwarwick (Jun 12, 2004)

Goldigger said:


> i always thought we needed to get the battery voltage as close to the output voltage as possible as excess voltage is wasted as heat??


I believe that's only for a linear regulator such as the lFlex. b3flex is a buck driver so it acts like a little switching power supply.

Buck converter - Wikipedia, the free encyclopedia


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## muzzanic (Apr 28, 2009)

I do like reading all this & love to see people pushing the limits, But really how much light do you need ??

I have always had big lights, At the moment My light has 9 XPG's approx 3600 lm & the need to run it at full power just isn't there.

This week I also have a triple XL-M light ariving ( running at 3a ) & I'm looking forward to trying it, But I can't see a need to run both these lights together.

As much as I like a big light, 
With many years of car rallying to fall back on I have found that not having all your eggs in the 1 basket is a wise move.

The chance of a light system failing when doing a high speed down hill run is low, But none the less is possable.

The chances of 2 complete different systems failing at the same time is very low.

So would not 2 of 3x XL-M systems be a good way to get around alot of problems & add safety.

Just asking ??


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## Goldigger (Nov 6, 2009)

Having a light that can run at max so in this case the OP is about a 7up XM-L PCB, doesn't mean it has to be run at full output..
7 XM-L's at 1amps = 2909.9 lumens vf 3 21v total, 21watts
3 XM-L's at 3amps = 2926.5 lumens vf 3.33 9.99v total, 30watts

Using more LEDs let's us keep the housing smaller as we have less heat to dissipate, if run at lower current as in my example above.
Downside is we need a higher voltage battery, but upside is we don't need high mah to get a decent runtime like we do when running LEDs at 3amps..


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## deesta (Sep 7, 2008)

I'm now seriously thinking that I'd like to do this upgrade to my 7-up light. And, now George has finalised it, thinking of using a hbflex to drive it. 

Thoughts? Is it doable? Will my 4s2p li-ion battery be ok (15v 5.2aH) ?

I can make a new rear to the light to take the new driver so that's not a problem. 

Anything else I should be aware of??


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## Goldigger (Nov 6, 2009)

Don't forget to make a mini egg frying attachement, the heat on full wack should be ample to make yourself some fried egg sarnies..


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## troutie-mtb (Sep 20, 2007)

Not been looking much on here just lately but the idea of a 7 or 8 xml light sounds cool .
Agree on the not needing to run at full whack but would like to now and again 

thing that lets it down is the optic choice with that much power I would want to see rabbits at 500 metres 

I am off somewhere sunny today and will have a think while relaxing on what to build next .

thinking 3 aspherics and 4 Ledil square or similar config as a light bar 

or even 7 aspherics and different degrees of focus to tune the beam .

Jay what about 7 aspherics in a tight focus for a dive light ??


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## deesta (Sep 7, 2008)

How big are the aspheric lenses Chris?


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## Goldigger (Nov 6, 2009)

Hi Chris..
It's chucking down with rain here! 

It really depends on the audiance the dive light is for..if its the DIR crowd they will say to bulky..
7 aspherics were looking at at least 100-110mm wide?
To be honest a SST-50 and a bigger aspheric does the job..

Another thing to consider is to many lumens washes out everything you shine it at..and burns fish 

But either way it will be interesting to see what you come up with..


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## muzzanic (Apr 28, 2009)

deesta said:


> I'm now seriously thinking that I'd like to do this upgrade to my 7-up light. And, now George has finalised it, thinking of using a hbflex to drive it.
> 
> Thoughts? Is it doable? Will my 4s2p li-ion battery be ok (15v 5.2aH) ?
> 
> ...


Don't waste your time.

I own 3 good lights that I only use 1 at a time & have never felt that I needed more light on high speed down hill tracks.

The smallest light output of them is a 30w HID light 1850 lumens, I don't use this much any more because it doesn't have a dip mode & uses lots of power on long rides.

The next light is a 3 XML Led approx 3000 lumen & on full, Well if you need more light IMO you need to learn how to ride better or need your eyes checked or both.

My 3rd light has 9 XP-G approx 3600 Lumen on full & IMO is a better light than the 3x XML but really there is not much in it & I just don't need that much light.

So if you just want to build a 7 up XML light then go for it but if you think it is going to be the answer to the best bike light setup it just won't be.

At full power your battrey just wouldn't be upto it.

If you did wan't to run that much power you would be better to spread it over 2 lights & go for the safety of if 1 was to die for what ever reason you will not be riding in the dark.

Just my 2 c


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## deesta (Sep 7, 2008)

muzzanic said:


> Don't waste your time.
> 
> I own 3 good lights that I only use 1 at a time & have never felt that I needed more light on high speed down hill tracks.
> 
> ...


The reason I want to do it is, simply, because I want to. I've got a 7-up XP-G light on my bars and a 4-up XP-G on my helmet. Both great lights but I enjoy fiddling with lights. As for improving my riding and getting my eyes checked...
I'm not looking to build the best bike light ever, just looking to try something new..:thumbsup:


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## Goldigger (Nov 6, 2009)

muzzanic said:


> Don't waste your time.
> 
> I own 3 good lights that I only use 1 at a time & have never felt that I needed more light on high speed down hill tracks.
> 
> ...


I think you've missed the point..yes it can put out 7000 lumens on high..but you don't need to run it on high..
Run it at 1.5 amps and it still puts out 4200 lumens..and with a lot less heat..even at 1amp 2900 lumens.
Then when you want to see everyone's face drop you can ramp it to full power
It's a simply upgrade for the 7up troutie light..

And more importantly its fun..


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## deesta (Sep 7, 2008)

Goldigger said:


> I think you've missed the point..yes it can put out 7000 lumens on high..but you don't need to run it on high..
> Run it at 1.5 amps and it still puts out 4200 lumens..and with a lot less heat..even at 1amp 2900 lumens.
> Then when you want to see everyone's face drop you can ramp it to full power
> It's a simply upgrade for the 7up troutie light..
> ...


It's an upgrade for *my* light GD...

I've just done a quick 3D drawing of my proposed new rear casing and, all in, I'm looking at around 75 sq" of surface area.. Hopefully that should help dissipate some of the heat


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## Goldigger (Nov 6, 2009)

deesta said:


> It's an upgrade for *my* light GD...
> 
> I've just done a quick 3D drawing of my proposed new rear casing and, all in, I'm looking at around 75 sq" of surface area.. Hopefully that should help dissipate some of the heat


Sorry ill rephrase what I said..its an easy upgrade for trouties 7up and deestars 7up light..


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## deesta (Sep 7, 2008)

:lol:


Goldigger said:


> Sorry ill rephrase what I said..its an easy upgrade for trouties 7up and deestars 7up light..


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