# Big Light Prototype



## StevelKnivel (Jun 23, 2007)

Here's a little something for those 4-5 hour epic backcountry rides with 40mph downhill sections. My goal with this light was to develop a light that's very efficient with long runtime at ~700 lumen and also provide 1500+ lumen when needed.

This light has 10 Q5 WG emmiters and I included 3 red emmiters to improve color rendering. Next time I think I'll use 3 amber emmiters instead, this one is a little too rosy for my taste. Driving everything at 600mA it should be putting out ~1800 lumen and consuming around 25W. The housing is 2.5" OD and 2" long and weighs about 250g complete. I made the wall thickness pretty thick on the housing and the optics are behind 1/4" Lexan, so this light should be indestructable!




























Beamshots will be coming soon. The light is with a friend of mine at the Icycle race (link: https://jandwevents.com/info.html ) in Fontana, NC right now for some night DH racing action. When he comes back I'll do some shots comparing the effects of the red emmiters with amber ones.


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## Baulz (Sep 16, 2005)

Very cool light. 


Please tell us more. Driver and batteries?


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## Prettym1k3 (Oct 11, 2005)

I'm curious about batteries, too.

What run times were you after? 2-3 hours? 4-5 hours? 6+ hours?

Battery weight to power this thing for those run times?


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## pepko (Feb 1, 2008)

good ...


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## StevelKnivel (Jun 23, 2007)

Driver for the production version will be custom with multiple levels and thermal protection. This prototype is running off a maxflex driving two parallel strings. Any battery from 7.4v to 14.8v, the light consumes roughly 10 watts on low and 25 watts on high. I'm using a 11.1v 4800mAh (53wh) Li-Ion battery that weighs about 275g and should give around 5 hours on low or 2 on high.


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## essenmeinstuff (Sep 4, 2007)

Nice


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## [email protected] (Jan 4, 2004)

That's cool. Mixing in the different colored leds is an intersting idea.


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## crisillo (Jul 3, 2004)

very nice! :thumbsup:


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## troutie-mtb (Sep 20, 2007)

Whoa that is a crazy light , where will this end 
I Luv it


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## Hack On Wheels (Apr 29, 2006)

StevelKnivel said:


> Driver for the production version will be custom with multiple levels and thermal protection. This prototype is running off a maxflex driving two parallel strings. Any battery from 7.4v to 14.8v, the light consumes roughly 10 watts on low and 25 watts on high. I'm using a 11.1v 4800mAh (53wh) Li-Ion battery that weighs about 275g and should give around 5 hours on low or 2 on high.


That is a pretty darn good total weight, not even 600 grams if I'm not mistaken. Very awesome; I must say, I want one! That would be a brilliant bar-mounted light.


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## mbaulfinger (Aug 2, 2007)

Steve, that's a great looking light housing. I also like the mounting bracket. Be nice to get a detail shot of that too if possible. Thanks for sharing it

Mark


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## mofoki (Feb 1, 2005)

My question is, how many of your projects are blowing the magic smoke? I've seen several of the builds you've posted here and although they are cute the heat control would seem to be inadequate. LED's 101 design factor in the heat removal properties first above all and I just don't see it in some of your designs. It's cool that you get everything to fit though. I've been building many light sets with leds and paying more attention to heat removal because of the problems encountered like the shorter than expected run times from the heat and inefficiancy. The projects that I've been happy with most and have performed the best seem to be of a larger profile with the MR-16 size enclosures. They run cooler and longer than expected. I just haven't found a MR-11 profile that puts out a nice beam and runs well either. Since you have the facilities to fab your own enclosures you should be thinking along those lines and coming up with something that last the expected 50,000 hour expected life of the led. :thumbsup:


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## StevelKnivel (Jun 23, 2007)

Mofoki- I was wondering how long it would take you to bash my work this time...

This housing has more surface area and slightly more mass than a Lupine Betty, which is also running in excess of 20watts at full power. It is not a small light! I spend a lot of time modeling and analyzing the shape of each housing I design to achieve optimum heat distribution, minimum weight and maximum surface area. The maxflex driving this particular light is thermally connected directly to the back of the MCPCB that the LEDs are mounted on for quick response to overtemp conditions. The thermal protection of the maxflex is set to 60deg C, which should limit max junction temp (Tj) to around 100-110deg C, safely below the max Tj for Cree XR-Es (150C) and XRs (145C). Running at 25w it takes 7 to 8 minutes sitting in still 75deg F air for the light to reach the thermal protection. At a walking pace outside with similar ambient temps the light doesn't hit the thermal protection. Running at 10w the light can sit in still air indefinitely without any problems.

To answer your question: 
Out of the 30 or so lights I've built there have been 0 failures. In addition to spending adequate time in the design phase, I believe that using high quality components and materials along with clean and methodical assembly practices is the only way to go. To me building LED lights is very similar to building a forced induction motor. It is very easy to turn up the drive current for LEDs, just like it's very easy to turn up the boost from a turbo. The increased output is tempting, but both systems get less efficient as they reach their upper operating limits, and without proper engineering both will fail. The goal is to maximize output by designing the system to operate within its window of efficiency. Also the reliability of both system relies heavily on small details. A loose oil fitting can ruin a $10,000 motor, just as a poorly soldered joint or a short against an aluminum casing can ruin a light. Point is, there are only a handful of components in these lights and with a little planning and proper assembly technique there shouldn't be any failures. Sorry for the rant...:rant:.


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## mofoki (Feb 1, 2005)

:skep: 


Sorry if I hit a nerve. If you're going to show your work here you must be prepared that not all replies are going to be positive and pat you on the back. I know alot of work goes into these things. I wasn't bashing you, just making an observation. I do know that materials play a big part in design, you can't just use any ol piece of aluminum, so you don't have to go on the defensive and tell me what you do for living that qualifies you "design" or carve a housing out it. I'll admit I've had some failiars but obvious you won't so lets just leave it that.


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## Finski (Jun 2, 2007)

I think that light is badass. Props.


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## znomit (Dec 27, 2007)

Stevel, very nice. 

Are they the tiny optics from cutter? I want to build a tiny linear triple or a quad and they look ideal.


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## StevelKnivel (Jun 23, 2007)

mofoki said:


> :skep:
> 
> Sorry if I hit a nerve. If you're going to show your work here you must be prepared that not all replies are going to be positive and pat you on the back. I know alot of work goes into these things. I wasn't bashing you, just making an observation. I do know that materials play a big part in design, you can't just use any ol piece of aluminum, so you don't have to go on the defensive and tell me what you do for living that qualifies you "design" or carve a housing out it. I'll admit I've had some failiars but obvious you won't so lets just leave it that.


Mofoki-
I welcome constructive criticism on these lights, the reason I post here or on CPF is to get feedback from knowledgeable people working on similar projects. If you presented your questions or objections to a particular aspect of my work in a tactful or professional manner I would be more inclined to listen to you. Starting your post with a question like "How many of your lights are blowing the magic smoke?" is a sure-fire way to piss someone off. Until you can reply to my threads with mature and technically sound opinions please don't fill them up with inflammatory lectures on why my heavily finned housings are inadequate heatsinks.



znomit said:


> Are they the tiny optics from cutter? I want to build a tiny linear triple or a quad and they look ideal.


Znomit-
They are available from Cutter. I'm using a combo of the 6deg and the 25deg optics: 6 6deg around the outer ring and 7 25deg on the reds and whites in the center of the light. They seem to be good optics, but the 6 deg has some artifacts in the beam (although with multiple emitters it is not so noticeable). Polymer Optics lists a 6deg smooth spot that is different than the standard 6 deg, but I cannot find them anywhere. They are really small! If you are in the US you can get them from LED Lighting Supply.


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## mofoki (Feb 1, 2005)

Are you still pissed off about me not buying that simple metal ring for $50 from you. 
If you get pissed off that easy it must suck to be you.


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## crisillo (Jul 3, 2004)

mofoki, please ... no insults


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## mofoki (Feb 1, 2005)

OK. I'm sorry Masterbuilder Knivel. I did not mean to piss you off. Your light builds are the best. They are definately pieces of art and masterfully crafted. You're a real brain to even think up designes that are so cool. How do you do it? I could never make anything that cool. I wish I had your tallent and the access to machine shop equipment but even then my work wouldn't come out as good as your's. You could probably make a fortune with the ability to make such sweet lights. I would like to buy one but I'm a poor unfortunate person who has to settle for a flashlight strapped to the bar or helmet, but if I ever get rich I would definately buy one made buy you. Do you etch you're signature into em too? That would really be great, a light signed by the master builder himself. What's next, a light that looks like the bullet chamber on a pistol? Oh sorry, I see you already did that. Man, the designing proccess must take weeks. I don't have that kind of time, being a Walmart Greeter is pretty demanding, but those are awesome. Thank you for letting us have the privilage of viewing your work, it makes me feel truely blessed.


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## Finski (Jun 2, 2007)

mofoki needs to lay off the Haterade.


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## mofoki (Feb 1, 2005)

What are you talking about? That was a sincere apology.


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## BikeMk (Mar 2, 2004)

How witty! How clever! How mature! How empowering! 
(teh ignore list +1. If everyone started ignoring the d-bags here, we'd have much more useful forums)


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## hurf de durf (Aug 23, 2007)

I don't mean to jump into the middle of things and rustle them up again, but I'd just like to share my experiences with Stevel's lights. I received one of his helmet mount version lights recently and I've used both his helmet mount and bar mount versions before I bought my helmet mount version as the MTB (or more aptly titled, "trail riding", given Florida's distinct lack of mountains) culture here is pretty happy-go-lucky and helpful in a grumpy grandpa sort of way. 

Anyways, the lights themselves can get warm (not hot) and they do not seem to suffer any runtime issues. I ran one for around 2 1/2 hours (the bar mount version) and had no problems with heat or otherwise. Among all the other people here that have the lights, this seems to be the general consensus. I hope to put my light through its paces and if I encounter any problems, Stevel will be the first to know. 

Oh, and one last thing: Stevel doesn't sign his lights, he simply leaves a lipstick stain on the receipt with his phone number scribbled on it...that's the Tarsier lighting systems difference!


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## mofoki (Feb 1, 2005)

It's good the lights don't have issues. But obviously you know who does. I didn't know you had to be tactfull or itelligent to ask a simple question in a forum. I thought using the term magic smoke was kind of making light out something going wrong or failing badly and I added it into a question. The point I was trying to make was that in general these applications don't do so well if you don't divert the heat and in a small enclosure you can't divert that heat. That's been my experience and why some of my boards have burn't out. I keep reading posts from people saying, I get 2 hours run time on high or more but the fact is if you run the lights that way they die, unless you can get rid of the heat. That's something I haven't been able to do well in simular builds such as the "Masterbuilder's". I am only trying to find a common point from which I can follow to build dependable housings and not get a bunch of returns and a bad name. I have successful builds but they all seem to be the MR-16 size. But them people say that's to big, it must be heavy. Anyway, I'm glad to hear you are happy with the lights and appreciate your honest input.


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## penquissciguy (Jan 22, 2008)

Sweet light. Wish I had the skills and access to the equipment to make things like that.

Do you have any pictures of the inside of the shell?

Ken


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## pimpbot (Dec 31, 2003)

*Yet....*



mofoki said:


> OK. I'm sorry Masterbuilder Knivel. I did not mean to piss you off.
> 
> ...
> 
> ...


You write backhanded stuff like, this.

Please, quit while you are behind. This is the most weaksauce apology I have ever read.

Dude, he makes killer lights. Why do you have to dump on him?


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## super-fast (Sep 28, 2006)

He is just jealous probably  

I did never have problems with a light getting hot while riding (but I am a roadie, so speeds are higher). 3 Rebels in a Minewt at 700 mA didn't became hot at all. I hoped I could use it to warm my hands, but that wasn't the case at all.

Nice light btw.


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## cytoe (Jan 20, 2004)

*13 leds?*

So you are running 13 led off 1 maxflex in 2 strings? ....6 leds in series (string 1) and 7 leds in series (string 2), with both string 1 and 2 run in parallel? If so, the led's get a maximum of 600ma (approx) each? I thought the strings need to be balanced (ie both equal number of leds) to run in parallel effectively. Just curious. thx


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## StevelKnivel (Jun 23, 2007)

cytoe said:


> So you are running 13 led off 1 maxflex in 2 strings? ....6 leds in series (string 1) and 7 leds in series (string 2), with both string 1 and 2 run in parallel? If so, the led's get a maximum of 600ma (approx) each? I thought the strings need to be balanced (ie both equal number of leds) to run in parallel effectively. Just curious. thx


You're totally right, the strings have to have a balanced forward voltage to receive the same amount of current. In this light the strings are pretty close to balanced with the addition of the three red Cree XR emitters. Red, red-orange, and amber Cree XRs have a forward voltage of 2.25v @ 350mA, while white XR-Es have a forward voltage of 3.3v @ 350mA.

The calculated forward voltage for the strings @350mA are: 3.3V x 6 = 19.8V for the 6LED string and (3.3V x 4) + (2.25V x 3) = 19.95V for the 7LED string. There isn't a perceptible difference in output between the two strings.


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## cytoe (Jan 20, 2004)

*nice*

thx for the info. the lower ma per led is probably a good thing too - less heat.


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## Tinier (Apr 13, 2006)

Hi Steve,
Have you tried running the lights in other configurations like perhaps a 5x2row or even 10x1 row format? Ignoring asthetics, I always wondered since illuminating the trail down/ahead is more important than upwards, would it be better to run it in a wider configuration. Anyway I find a helmet light is far better to light up those pesky low branches.

It might give a better spread of light..so I'm curious if you tried something like that before.


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## StevelKnivel (Jun 23, 2007)

I definitely want to explore some alternate layouts, although the secondary optics determine the shape of the beam more than the layout of the emitters. This light has a combo of 6deg and 25deg optics and the 25deg flood optics shoot a lot of light up into the air. Polymer Optics make some 6x25deg elliptical optics that I'd like to try out. Check out Troutie-mtb's 6 Cree light ( http://forums.mtbr.com/showthread.php?t=376853 ), it's awesome! He's using a mix of elliptical and regular optics and the beamshots look killer! Speaking of beamshots, I'l post some up here soon. I just got the light back and I'm going on a ride with it tonight, so I'll try to take some pics.


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## StevelKnivel (Jun 23, 2007)

Finally some beamshots! This is with 10 XR-E Q4s and 3 XR Amber emitters.
(All shots F2.8, 2sec, Canon A620, Daylight White Balance)

Here is the big light running approx 600mA (~25w) with 9 25deg optics and 4 6deg optics:









This shot is the big light running approx 250mA (~10w)









for comparison, here is my personal triple Cree R2-WH, Cutter 14deg optic helmet light running at 900mA (~10w):









I am pleased with the output of the big light to say the least! The earth-tone colors are rendered clearly and it puts out a wall of light yet still manages to throw pretty well. The 13 individual optics allow the beam to be fine tuned from flood to spot by running different combinations. This combination is the best balance I found to suit my preference for a bar mounted light (lots of flood with minimal hotspot). I can only imagine how this thing would throw with 13 6deg optics, I'll put them in this weekend and find a good spot to go take long range beamshots. Cheers!


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## znomit (Dec 27, 2007)

You're gonna need a bigger backyard to do beamshots with the narrow optics. 

What I would like to see is a beamshot comparison with the triple at the same total power.


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## OldAusDigger (Apr 8, 2008)

*What's happened to the "Big Light"?*

Steve, has this progressed beyond the 1st prototype you did a few years ago? Would you consider building a "Big Light Mk-11", chock full of XPG goodness? If they made it to the market in any numbers, has anyone here had experience with this awesome looking light?


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## StevelKnivel (Jun 23, 2007)

Hard to believe I built this 2 years ago! Man I'm getting old fast. I'm still running this light as my go-to handlebar light. It's been great and still has a nicer tint than anything else I've used. I didn't follow thru with a production run, more fun to keep it as a hobby and no one really wanted a motorcycle light on their bike back then... Now days you can get the same amount of output from a tiny 4x XPG light like Troute's Baby Trout. Pretty amazing progress in the past few years... If you wanted something similar you could build up one of Troute's 7-up setups with R2 bin 4D neutral tint XP-Es. Those have an awesome color too!

Cheers,
Stevel


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