Yeah, you're right. Please let us know when you've got the build complete. I would love your permission to link to it over at the mtbr forums DIY Light section. I think the biggest bar light I've seen over there is 10 LEDs, but they were pretty small ones, arranged 2x5.
I'll take two! One for the roof and one for the front bumper. 
I'll keep this thread updated with my progress on the build. Right now, I have to finish the circuit board layout, get PCBs fabricated, build up the parts (LED's, microcontroller, Buck-Boost sections, etc.), debug, and then physically assemble the unit. Lots to do..
As for linking to another forum - Please feel free. I enjoy sharing my work and ideas.
PPtk
Picture not showing up - but I actually have considered selling these once I have the design working and debugged.. I'll keep you informed if I decide to do that..
PPtk
Yes please do. Idea of total costs?
Too early to say.. I haven't looked at the costs of anything in any type of quantity. The cost for this one is about a gazillion dollars :) It would be far more reasonable if I were building 20...
gz mean congratulations ...for the birth of your project, maybe is not the most appropriate adjective but my english is very poor sry xD
finally I got what mean the title, ty(read above xD)
mmh was really close to your answer... I think, ty xD
You do fantastic work. Can't wait to see the finished product :)
Thank You! That makes two of us :)
The vast majority of the reason I 'built my own' light like this is that I found the thermal charachteristics of most of the commercial stuff.. well.. terrible.
All of the big brands out there build their lights on an extruded aluminum frame. The problem with this is that, even when they do extrude heat sheading 'fins' into their frame - they face the wrong way! I don't drive sideways!
After a lot of reading, I found that most of the available stuff has serious heat problems. ALL of the lights have a small-print disclaimer about their brightness claims and it's all because of heat. They have to back off on driving the LED's because the whole assembly gets too hot.
So - 6 months later - here we are, and I've started building my own. Before I went down this road, I did plenty of thermal analysis, and I thought you might enjoy seeing some of my results.
Here are two cut-plots of the steady-state temperature of the light. These temperatures assume that I am driving 24 XM-Ls at 3 Amps Each (240 Total Heat Watts), and they assume that its 90 degrees F (32 degrees C) in the ambient environment. They also take into account a light breeze (2 MPH) passing from front to back. The numbers would be far better with even a few more MPH of airflow. These are worst case scenario.
As you can see, I can easily drive all 24 emitters full-blast for as long as I want, even in 90 degree weather. The careful thermal design of this light is what allowed me to cram 240 watts of LEDs into a bar that is 15" long rather than 48" long.
Cut-Plot JUST behind where the actual LEDs are mounted. This is the hottest part of the entire light.
Also visible are the trails of cooler (but still quite warm) air as it passes through the fins at 2MPH.
Side view Cut-Plot through about the center of the enclosure. You can see one of the lenses and an entire fin.
Hope you're all enjoying my ramblings about this project. I really can't wait to get it lit up.
PPtk
Gonna need some beamshots of this baby! Looks fantastic!
-Garry
Interesting Pilot. You are so right about the heat sinking fins on lights. For bike lights, they usually face front to back so air is flowing over them. As a matter of fact, most bike lights get quite hot standing still because they were designed with air flow in mind. Here's an example you might find interesting. Troute started as a DIY guy.
wow
thermal analysis, and to an extent that very few, if any, manufactured lights get
that is one squared away flashaholic!
That is quite an impressive project! 
Can you give us a list of software you used for this?
That's ok. It was just a picture of my old trail Jeep (XJ). But yeah, keep us posted if you do decide to make them for sale. I've been holding off installing any aux lights because nothing really struck my fancy. This looks like a winner!
Nice, thumbs up for figuring out the cooling!
Some serious driving, 24 XM-L´s at 3A :o
At least I would be satisfied even with a little less of current with that amount of emitters :D
Wow.
I wish there more threads like this. 24 XM-Ls . . . farking awesome.
farkFoy
Really great :)
Cant wait for the result!
Fritz
Sorry I've been gone for a while - Life got busy, as life tends to do once in a while..
dthrckt, Thanks very much for the 'wow' :) Thermal Analysis is quite amazing today - My suspicion is that the big guys don't do it because they don't want to know :)
The Solid Modeling was done with SolidWorks 2011
Thermal Analysis was done with Solidworks Flow Simulation 2011.
CNC CAM was done with Mastercam X4.
Circuit board Schematic Design was done with Orcad Capture CIS
Circuit board Layout/Route was done with Cadence Allegro 16.3
More to come!
PPtk
Had a few minutes the other day, so I threw together a schematic and layout for the circuit board that will carry the LED's and the drivers. I may consider sharing this once it's been debugged and proven to work.
Here's what went out to be fabricated. Should have it back in three or four days.
Overall, the board has 1,678 vias - the vast majority of which are strictly for helping move heat away from the LED emitters and into the enclosure.
The board was designed for 30 Amps of current (Max current with 24 LEDS at 3A each is about 20 Amps) with less than 0.05V of drop across the 14 inch length. Each group of 3 LEDs will be infinitely and independently variable in brightness. PWM Frequency of the constant current drivers will be 500 KHz, so there will be NO audible hum or visible blink. With the particular N-Channel MOSFETs and ultra-fast recovery Schottkys that I've picked, efficiency of the driver should be 92.. maybe 93 percent. Not bad..
PPtk
