# 21 XLM's....overkill or no



## Psycho Mike (Apr 2, 2006)

A fellow DIYer on another board posted a link to a 7 XLM'S board that he indicated "2 on the bars and 1 on the helmet should do nicely." Doing the math, driven at 3A, that's a nominal 6,300 Lm per light x 3 lights....say 19,000 Lm.

I'm thinking that'd be serious overkill....as in whiting out trail details and hurting the night vision for anything on the perhipery of the field of light, etc.

Sure, it would be a great DIY exercise, but does anyone here think such a set-up would be practical for actual field use on a bike?


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## troutie-mtb (Sep 20, 2007)

Hi Mike 
not seen you around here for a while .

very overkill imho and what sized powerpack will he be lugging around .

from the days when I did the stupid bright lights I did an experiment adding lights to see how much was too much and my findings were about 3000 lumens on the bars and the same on the head was well overkill but usable any more was not adding to the usable trail light at all 

Maybe suggest to the poster that he would be better with less leds and better optics instead of the Nuke em approach

have you a link to said board for us to peruse


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## Goldigger (Nov 6, 2009)

I'd say overkill..maybe 19 max 

But I'd like to see the crazy light 21 xm-l's put out..

Chris can you do a beam shot of 7 dominators all @ 3 amps please:thumbsup:
Actually let me know what time later when's its dark and ill look north for a second moon


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## troutie-mtb (Sep 20, 2007)

Goldigger said:


> I'd say overkill..maybe 19 max
> 
> But I'd like to see the crazy light 21 xm-l's put out..
> 
> ...


see this post 

dont now know how many lumens


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## mattthemuppet (Jul 16, 2004)

it's not just the weight of the battery that would be of concern but the housing surface area (and weight) needed to cool the lights. I can't imagine having a light large enough to cool 7 XM-Ls even at 1.5A on my helmet, although I guess I'd get a ruggerbugger's neck as a plus 

Of the few truly monster lights I've seen on here, only one or two have a decent and useful beam. Most of them are just masses of unfocussed flood, which would probably be harder to ride with (due to night vision being shot and not enough throw) than a smaller light with better optics. Still, it's always fun to see what people come up with!


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## brent878 (Apr 17, 2007)

with more light I think you would just need to aim it our further. I run about 4000 lumens on my dirt bike with combo of bar and helmet lights and I could use more. A little different than a mtb bike but at 60 mph I wish I could see farther ahead than my 4000 lumens will throw. With more lumens I would just expect that you can see farther down the trail. How much is overkill will depend on the rider and there intended use.


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## Psycho Mike (Apr 2, 2006)

Ok...looks like the potential for 20,000 lm is there, but upon seeing this thread, the poster on the other forum feels I was being dishonest in my description. He's thinking of using a lower current for less heat and more efficiency (he hasn't stated what that proposed current is or his anticipated light output...the 20,000 lm potential output is the only actual number he posted). Still, 21 XM-L's seems like overkill for a mtb light setup.

His current set-up is 7 XM-L's: 2 @ 3.05A, [email protected]: he figures it's ~6300 lm output.

Myself, I'd say event that 6300 lm is probably overkill. My little XR-E home-brew triple pushing 1A (bFlex) is good for a nominal 825 Lm...when added to my old 15W halogen I use as a helmet light, I'm probably sitting somewhere in the order of ~1100 Lm total and that's a pretty decent amount of light for trail riding to 25km/h (IMHO, depending on optics). 6000+ lm is a lot of light....I'd be afraid of whiting out details on trail or losing the night-vision outside the beam area.

What are people's thoughts? Where is the "Sweet spot" and is 6000+ lm (think light in the order of 3x16* Lupine Betty lights) overkill for a mountain bike light set-up?


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## Psycho Mike (Apr 2, 2006)

troutie-mtb said:


> Hi Mike
> not seen you around here for a while .


Yeah, been fairly content with the D-Star Altair chassis I built up with Cree XR-E's and the not-dead-yet 15W halogen, so I haven't dropped by this forum a lot in the last while. When the halogen dies, I'll be here a bit more...to see about moving the D-Star to the helmet and build something "new" up for the bars


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## mattthemuppet (Jul 16, 2004)

I like my 2 [email protected] (bar) and 2 [email protected] (helmet) a lot, though I mostly run the bar light @~1.9A to match the helmet light better. Wouldn't mind running the helmet light @2A, but it's not really necessary and would need need a driver change.

So, ~3000 theoretical lumens, good 2:1 bar:helmet ratio and almost the perfect beam pattern for me (although I'm still fiddling with the helmet optics). I haven't out run it yet, although my speeds rarely exceed 20mph if that.


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## mrradlos (Sep 3, 2010)

mattthemuppet said:


> it's not just the weight of the battery that would be of concern but the housing surface area (and weight) needed to cool the lights. I can't imagine having a light large enough to cool 7 XM-Ls even at 1.5A on my helmet, although I guess I'd get a ruggerbugger's neck as a plus


The housing doesn't need to be very big, when driven at 1.35A. You can buy a hole DIY-kit with board there.



troutie-mtb said:


> have you a link to said board for us to peruse


And a second, different board here (U2 binned).


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## Goldigger (Nov 6, 2009)

mrradlos said:


> The housing doesn't need to be very big, when driven at 1.35A. You can buy a hole DIY-kit with board there.
> 
> And a second, different board here (U2 binned).


consensus on this thread suggests that the 7up optic in your link is pretty inefficient with xm-l's..
http://forums.mtbr.com/lights-diy-do-yourself/35mm-7up-xml-board-759367.html

Can you provide a beam shot please if possible?

That kit in your link says xm-l, but the PCB looks like xpg's?


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## mattthemuppet (Jul 16, 2004)

mrradlos said:


> The housing doesn't need to be very big, when driven at 1.35A. You can buy a hole DIY-kit with board there.
> 
> And a second, different board here (U2 binned).


true, but I still wouldn't want it on my head  That'll be ~30W, give or take, so equivalent to a 3up XM-L @3A, although slightly more efficient and probably the highest drive current you'll get out of a boost driver.

It just seems and expensive and awkward way to arrive at the same point - I'd rather have a smaller light with better optics and a smaller battery.


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## oreophilus (Mar 22, 2005)

the trolls were *****ing about the number of lumens my lights projected (somebody purchased a single budget Chinese XLM spot light placed on the handlebars, so that is the standard of quality we must not cross), so I advanced a hypothetical that ain't that far off, since using leds at low current provides more lumens per watt at lower heat

the Betty already uses a number of XMLs within the 7up array and provides spot, med and wide angle versions

judging by the year by year progression, someone shouldn't make their previous year's build as the standard, since bike lights are continually evolving

when you were freeking out at 200 lumens in years past









don't say it's not a posibility, it's already here

wide and med on handlebars









helmet spot


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## mattthemuppet (Jul 16, 2004)

each to their own, although just because something is possible, doesn't mean that it's desirable


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## oreophilus (Mar 22, 2005)

mattthemuppet said:


> each to their own, although just because something is possible, doesn't mean that it's desirable


the only undesireable thing about a Betty is the price

they've got the leds-optics-driver-housing-battery-charger pretty much perfected

many XMLs (XP-Gs) driven at low current gives the most lumens per watt and lowest heat


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## mattthemuppet (Jul 16, 2004)

hmm, this is turning into a Lights and Nightriding Forums "my opinion is better than your opinion" slanging match, rather than the usual friendly helpful atmosphere conducive to making *DIY* lights. Lets keep it focused on the DIY aspect, ok?


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## Goldigger (Nov 6, 2009)

I'm curious as to which optics are in the betty 12, looks like they thought the khatod and polymer 7up optic wasn't up to the job..
Is that an led in the middle?


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## oreophilus (Mar 22, 2005)

Goldigger said:


> I'm curious as to which optics are in the betty 12, looks like they thought the khatod and polymer 7up optic wasn't up to the job..
> Is that an led in the middle?


from their website


> *LENS SYSTEM*
> 
> *Perfectly matched*
> 
> ...


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## Vancbiker (May 25, 2005)

oreophilus said:


> the only undesireable thing about a Betty is the price


Not for everyone. The big round form factor does not work for me.


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## [email protected] (Mar 28, 2007)

troutie-mtb said:


> see this post
> 
> dont now know how many lumens


Troutie,

It looks like the moth (or some other insect) we see above the main hot spot and slightly to the left is actually smoking. Hmmm ... I wonder if there is a market for a 7 XM-L mosquito fryer ?

With 21 XM-L's you might be on the verge of a death-star style planet destroying beam. I could have used one of those when a nice inattentive grandma in an old Lincoln nearly kneecapped me today. Oh, it wouldn't have been right, but it would have felt good for a little bit.

Mark


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## mrradlos (Sep 3, 2010)

Goldigger said:


> consensus on this thread suggests that the 7up optic in your link is pretty inefficient with xm-l's..
> http://forums.mtbr.com/lights-diy-do-yourself/35mm-7up-xml-board-759367.html
> 
> Can you provide a beam shot please if possible?
> ...


I don't own any of this lights, but you get beamshots here and here. Throw seems to be surprisingly well...

They also have a xpg and xre 6 up DIY-light, but the one named "RA-7XML " uses the Cree XM-L.


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## izi (May 8, 2006)

this is the 22° optics you are looking at with the 7x-XP-g led's,...
it use to be 16° optics until riders start to complain that the beam is too narrow, so they solve this problem with centre led,...

Lupine developed their own optics,...


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## troutie-mtb (Sep 20, 2007)

izi said:


> this is the 22° optics you are looking at with the 7x-XP-g led's,...
> it use to be 16° optics until riders start to complain that the beam is too narrow, so they solve this problem with centre led,...
> 
> Lupine developed their own optics,...


And the prices Lupine charge I guess they can afford too.
for those prices I would want it hand delivered by a luscious concubine and a years supply of German beer


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## izi (May 8, 2006)

troutie,...
hehehehe,...

not everyone are able to DIY a good MTB light,...

I am developing my for a long time and at the end I just buy some used Lupine Betty optics with 7x XP-G leds, put it in my custom housing, MaxFlex,... the rest is well known to you,...

Cheers,
Iztok


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## brum (Dec 19, 2004)

Does anybody know who fabricates the Lupine optics?


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## marv2097 (May 19, 2011)

Regardless of people having lumen fever or not I would love to see what kind of heatsinking this many XMLs would need!


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## izi (May 8, 2006)

not much need for heat sink 7x CREE XM-L led's, because they are much under driven and the heat/watt ratio is much lower than with CREE XP-G

XP-G
Low thermal resistance: 6°C/W

XM-L
Low thermal resistance: 2.5°C/W

because Lupine offers DIY upgrade to XM-L from XP-G led's, the output current is same,...


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## Vancbiker (May 25, 2005)

izi said:


> not much need for heat sink 7x CREE XM-L led's, because they are much under driven and the heat/watt ratio is much lower than with CREE XP-G
> 
> XP-G
> Low thermal resistance: 6°C/W
> ...


An XPG or XML driven at the same current will need almost identical heatsinking. The spec quoted here relates to thermal resistance of the LED package. The ability to move heat from the XML die to the outside world is one of the reasons it has higher output and can be driven harder than previous generations of LEDs.


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## rob1111 (Jun 16, 2009)

Lupines optic are developed here:

UPT-Optik - UPT - Ultrapräzision Technische Optik
OEC: Home

soure:
Lupine Lighting Systems - Technologie - Betty


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## chelboed (Jul 29, 2005)

Chiming in late here...my own personal experience...I found a dual XP-G setup with Regina's on the helmet and a 20mm triple XP-G with narrow optics on the bar was such a perfect setup. The XP-G's with optics gave a nice flood over XP-E's...and the double barrel Regina on the helmet was about the most perfect beam I've ever played with.

Batteries were very light and manageable.


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## Goldigger (Nov 6, 2009)

I made one of my tripple XM-L's for a guy on one of the sites I work at, he was well impressed with the output of the 3 x U2 XM-L's..
Then he asked for another one, I assumed it was for his Mrs, I was wrong..
This is what he text me after riding with them both "Two on high well bright is bright. But on the road two on medium is fantastic just nice to know if one goes flat you have another glad I got another one."

He also said he rides up this road with no lighting and has one of the tripples on high, the tankers keep flashing him that come out of the oil refinery..this was before he had two tripples so god knows what the tankers will think now..or do..

He's also had people pulling him over to ask about the light, including the police!

I think one tripples XM-L is plenty..two insane..21 overkill


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## brad72 (Jun 12, 2009)

My brother always knew it was me riding from about 200 meters away from how bright my 7 up on high was. The 3 xml is as bright as the 7 up so 6 xml must be insane. I did always dip my lights to low or medium when traffic came towards me just so I didn't blind them and because some of our drivers have a habit of throwing bottles at you if you piss them off.

However if the roads are wet I could have really done with another 7 up as wet bitumen really seems to absorb the light.


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## Steamdonkey2012 (Jan 29, 2012)

I think it would be crazy overkill. I did some experiments with this Bridgelux array, good for ~12500 lumens, and it practically set my backyard on fire. Side by side testing with an MJ 808 was a total laugh. That much light should only be used if you're riding on your own planet.


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## oreophilus (Mar 22, 2005)

Steamdonkey2012 said:


> I think it would be crazy overkill. I did some experiments with this Bridgelux array, good for ~12500 lumens, and it practically set my backyard on fire. Side by side testing with an MJ 808 was a total laugh. That much light should only be used if you're riding on your own planet.


you could have the light hover over you and follow you in an HC helicopter providing you the night sun

the point about using many XL-Ms is to use them at low current to get the most light at the least heat with efficient use of the battery (less A/hr being converted to heat, thus wasted), and less weight for the housing since it doesn't have to dissipate the heat generated by the inefficiency


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## jase.paluzzi (Apr 23, 2011)

Goldigger said:


> I'm curious as to which optics are in the betty 12, looks like they thought the khatod and polymer 7up optic wasn't up to the job..
> Is that an led in the middle?


The Betty sure is a thing of beauty. I'm interested in this 21 XML build. No such thing as overkill!!! :thumbsup:


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## Steamdonkey2012 (Jan 29, 2012)

jase.paluzzi said:


> The Betty sure is a thing of beauty. I'm interested in this 21 XML build. No such thing as overkill!!! :thumbsup:


It's a thing of beauty until you find out how obscenely overpriced it is. Yikes...


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