DIY Offroad LED Light Bar

58 posts / 0 new
Last post

Pages

kevinthefro
Offline
Last seen: 5 hours 9 min ago
Joined: 07/25/2017 - 17:44
Posts: 26
Location: Torrance, California
DIY Offroad LED Light Bar

I dub thee: El Jefe.
It is the boss is because it starts out cold at 270 watts (about 35,000 raw lumens), then when it warms up, it stays at 270 watts. Indefinitely. Even if it is 100F degrees outside. And the car is not moving. This is much more power than “high-end” light bars can sustain. They start out at 100%, then automatically dim the light after a few minutes to avoid over-heating. This is called “thermal management”.

I designed a thermal management circuit at the start of the project, but decided not to use it because the idea of dimming seemed contradictory to having a high-power light. HIDs don’t dim, incandescents don’t dim, why can’t LEDs maintain full power indefinitely too? The answer is: they can, with enormous heat sinks made from time, money and pain.

Below are before and after photos all taken at ISO 100, f8, 1 sec shutter. Afterward I raised the black level (identically across all photos) to approximate the real life visibility. Stock high beams are the reference.


Shot 1 – Standing on the roof rack to try to capture the field of view.
How sharp is the curve ahead? Spotlights don’t help with that question. A spot would be pointed off the trail 80% of the time. El Jefe’s lenses have an elliptical pattern, basically a spot vertically but a flood horizontally, 13 degrees by 46 degrees. The extremely wide field of view is a little surreal – the visible area is much wider than the windshield, and your peripheral vision is seeing things through the side windows, similar to daytime. Driving is eerie in that the lighting doesn’t move as the steering wheel is turned, it’s everywhere. It’s fantastic.
I’m going to tilt it up 1-2 degrees to put a little less light on the ground in front.


Shot 2 – Normally, having an LED light bar with a white hood is like a pig farmer wearing a white suit to work.
Over-windshield mounted light bars put so much glare on the hood that many people paint or wrap the hood matte black. Rather than do that, I mounted it back from the windshield to let the roof shield the hood – just like the old days when pickups mounted their KC lights behind the cab. Grille mounted lights are more prone to being obscured by rocks and bushes.


Shot 3 – The only light on the hood is reflected off the hill.



Shot 4 – A spotlight would show where the trail isn’t. The wide beam makes it much easier to find landmarks and turnoffs. This light was designed for following twisty desert trails at 30 mph on Friday night looking for the camp site because I’m already late.


Shot 5 – Entrance to Wall Street Canyon. Just because it looks cool.


In order to maintain power continuously without dimming, I had to come up with an unusual heat sink design.
Most manufacturers use the same heat sink design, with minor variations, and that plays a bigger role in the light output than the advertised power. For example, if a given physical size can dissipate 115 watts, it won’t matter if one light bar is 200 watts and another 400 watts – they will both settle to 115 watts after they warm up and thermal management kicks in.

Typical horizontal heat sink fins simplify manufacturing, but most of the surface area is wasted since fresh air can’t really get in between the fins and just skims the tips. Bolting a couple of CPU fans on the back of a light bar to force air between the fins wouldn’t be difficult (I actually searched for waterproof fans), but probably not durable. Instead I opted for slicing the heat sink up like a loaf of bread and mounting the fins vertically. It was a ridiculous amount of work, but the short vertical fins are exposed to fresh air across their entire length without any stagnant pockets.

I learned the hard way, spending many hours building prototypes, starting with the cheapest heat sink in the foreground and reluctantly working up to the biggest to sustain El Jefe’s 270 watts. I wanted a low-profile light and I hated the way the big heat sink looked, but I’ve warmed up to it. Getting the most lumens out of those watts comes after.


Early prototype with short heat sink and Carclo elliptical lenses. TIR lenses focus more of the lumens and lose less as spill than typical reflectors. Spill on a vehicle mounted light mostly glares off the hood, saturates the ground 4 feet in front of the car, or goes off into space.


Three LED prototype of the final design undergoing heat torture test. The meat thermometer was surprisingly effective. The temperature was recorded in 30 second intervals for half an hour, when it stopped rising, then the results of all the tests were graphed and compared. For consistency, there needed to be absolutely no airflow across the fins other than natural convection. I noticed that just moving my hand past the sink too quickly would cause the temperature to dip.

In this test with 6 watts per inch of width the temperature leveled out at 137F in 70F ambient. Painting the fins black produced virtually identical results so didn’t have an insulating effect. Projecting these numbers to 100F ambient, it should peak at 167F. With the thermal losses between the LED, circuit board, frame and heat sink the LED chip should be very close to the binning temperature of 85C (185F). No thermal management dimming needed. I just need to take care not to leave the light on, parked, with no wind in 105F weather.


Done designing, starting the build. I made a jig to drill the holes consistently on the drill press. The stops increment at 25mm, with different spacers for different offsets. In case I make another…


Creating the frame by turning a rectangular tube into a channel with a table saw. The non-ferrous blade in the table saw made a clean cut but it was risky. A band saw with file cleanup would have been safer.




Rather than reposition the jig for each row of holes, I used a system of wood blocks as spacers for the various mounting holes so I could leave the jig locked down and offset the frame from the sides by the same amount every time. Measuring one hole at a time would have been miserable and error-prone. 


From http://www.heatsinkusa.com/ That pile of shavings is from hand-filing the mounting surface absolutely flat for maximum heat transfer. Took three hours. Great for the triceps.


Moved the blade to the miter saw and cut the heat sink into slices. I didn’t think to account for blade thickness and losing over an inch of material just for the cuts so I ran short and had to order another chunk of extrusion.


Drilled and tapped for M3. That tapping guide is the most clever invention ever. I broke two taps going in crooked before, none after I started using it. http://www.shop.biggatortools.com/product.sc?productId=5&categoryId=4 The tap is from MSC Direct and it cut 10 times better than the consumer taps. Buying professional drill bits and taps turned out to be well worth the cost.


Test fit. The saw marks on the fins were unacceptable.


The accuracy and finish from the miter saw was pretty good but not good enough so I fly cut to final dimension and finish. This added another week and a half to the project. I didn’t know what a fly cutter was until I needed one, then I had to learn how to make it and learn how to use it. I’m an electronic engineer and I thought I was starting an electronic project but 90% of the time and difficulty was in machining.


One set of M3 screws clamp the heat sinks to the frame to the star boards like a big sandwich. That saved another 180 holes drilled and 90 tapped over using separate screws.


Using the light bar frame as guide to drill the faceplate (.220” thick acrylic). I’ve noticed light bars on other cars starting to yellow with age, just like old headlights, so instead of using polycarbonate like everyone else, I used acrylic, which does not turn yellow in the sun. Polycarbonate is stronger than acrylic, but even acrylic is 16x stronger than glass and I don’t think the yellowing is worth it.


180 holes drilled for LED and heat sink mounting, 75 for current drivers, 24 for end plates, 3 for the power cable, 88 for the faceplate, 4 for the mounts, 1 for a Gore vent.
375 holes drilled, 228 hand-tapped.


Cleaned of all shavings and cutting oil and ready for primer.


Cree XP-G3 70 CRI minimum. 4000k for a neutral white. 777 raw lumens each driven at 2 amps (6 watts). Reflow soldered to SinkPad MCPCBs on the electric stove.


45 LEDs in gangs of 3. Soldering the wires onto the star boards was like trying to boil water with a lighter. The copper MCPCBs are amazing at pulling away heat.


Russian LED current drivers from eBay. Configured for 2A. There are lots and lots of current drivers on eBay but I liked these for compactness and no frills – no strobe or SOS modes etc. El Jefe has only one mode: ON.


The 14 ga power cord continues inside to become the power buss, with taps for each driver. Space is so tight I used the chassis for ground to eliminate one wire. Even so, that 14 ga white wire barely fit. Lens mounts are epoxied to the star boards.


15 current drivers, blue tape to hold them in place while soldering.


In order to get the lowest profile possible, I let the current drivers obstruct some light. I aligned the inductors to block the least possible.


The design is for function, not for looks. The frame has an extra 12mm in front of the faceplate to block most of the spill from going into the sunroof. The amount of spill is small as a percentage, but even a small percentage of 35,000 lumens is a lot of light. I had an ebay light bar which looked cool but didn’t light up anything but the dashboard. People keep asking me why I took the light bar off my car, because El Jefe blends into the roof rack and they don’t see it. Deutsch connector mates to a Rigid wiring harness.


Mounts cut from discarded HP server mounting rails and gas-welded to cheap roof rack. Building a custom roof rack is the next project.


Not bright at all off-axis and it adds no wind noise.


It’s physically painful to look at even in noon sun.


Pretty lens flare.

Edited by: kevinthefro on 11/03/2017 - 15:59
timbuchanan
Offline
Last seen: 1 month 4 days ago
Joined: 06/12/2016 - 18:26
Posts: 37
Location: NZ

What did it cost to build?

EasyB
Offline
Last seen: 4 hours 31 min ago
Joined: 03/09/2016 - 15:24
Posts: 1196
Location: Ohio

Awesome, I enjoyed the read. Thanks for sharing.

So each LED is getting 2A? Those elliptical TIRs seem like they work well in this application. Great beamshots too. Thumbs Up

apt323
apt323's picture
Offline
Last seen: 6 days 10 hours ago
Joined: 03/19/2012 - 20:18
Posts: 1481
Location: North Texas

Super Awesome!

kevinthefro
Offline
Last seen: 5 hours 9 min ago
Joined: 07/25/2017 - 17:44
Posts: 26
Location: Torrance, California

timbuchanan wrote:
What did it cost to build?

I planned to spend 200-300 but it came out to 500-600.
EVERYTHING came out wrong the first time and had to be done over at least once.
It took all winter, couldn’t finish in time for the spring desert trips, couldn’t stand waiting until the Fall so I went out to Calico last Friday night and back just to take pictures. It was 92 degrees at midnight.
kevinthefro
Offline
Last seen: 5 hours 9 min ago
Joined: 07/25/2017 - 17:44
Posts: 26
Location: Torrance, California

EasyB wrote:
So each LED is getting 2A?

Correct! Max drive current for the XP-G3.
Angler
Angler's picture
Offline
Last seen: 6 hours 6 min ago
Joined: 07/21/2014 - 21:30
Posts: 574
Location: South Carolina

Epic first post! Bravo!

Wow! Such bright! Many collection! Very torch! Amaze.

EasyB
Offline
Last seen: 4 hours 31 min ago
Joined: 03/09/2016 - 15:24
Posts: 1196
Location: Ohio

Offroading looks like a fun way to get out in nature and a great way to mount powerful LED lights!

Are you also interested in powerful handheld lights?

CheapThrills
CheapThrills's picture
Offline
Last seen: 15 hours 22 min ago
Joined: 07/02/2011 - 10:45
Posts: 3488
Location: Suomi

Looking good !! Smile

Lightbringer
Lightbringer's picture
Offline
Last seen: 57 min 40 sec ago
Joined: 08/30/2016 - 14:12
Posts: 3180
Location: nyc
Angler wrote:
Epic first post! Bravo!

What he said… Big Smile

09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0

MRsDNF
MRsDNF's picture
Offline
Last seen: 3 hours 20 min ago
Joined: 12/22/2011 - 21:18
Posts: 11690
Location: A light beam away from the missus in the land of Aus.

What an amazing build. Reading through your post was enthralling. Thanks for taking the time to post it up and well done on a super effort. Thumbs Up

My current and or voltage measurements are only relevent to anything that I measure.

Budget light hobby proudly sponsored by my Mastercard and unknowingly paid for by a hard working wife. 

djozz said "it came with chinese lettering that is chinese to me".

old4570 said "I'm not an expert , so don't suffer from any such technical restrictions".

Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

 

-X3-
-X3-'s picture
Offline
Last seen: 57 min ago
Joined: 07/16/2014 - 03:28
Posts: 1684
Location: France, Angers

Awesome project, congratulations !
I love the shape, minimalist design yet great functionality !
Did you have any problem with the russian drivers ?
I use on to feed my motorcycle auxiliary lights and find pretty reliable.

"Hey -X3-, do you have a flashlight ?"   "-X3-, can I borrow one of your flashlights ?" 

My Flashlight public album (mods, emitter swaps, eye candy)

My reviews channel (French language, Olight, Thorfire : 30+ lights tested)

My personal channel (including Olight SR mini, S1, S2, S1A and S-mini disassembly)

will34
will34's picture
Offline
Last seen: 1 month 1 day ago
Joined: 12/18/2012 - 00:12
Posts: 3193

Amazing build! Love the slim form factor.

FPV
FPV's picture
Online
Last seen: 4 min 22 sec ago
Joined: 07/14/2017 - 12:36
Posts: 223
Location: traveling

thank your for sharing this amazing first post. welcome to BLF!

FmC
FmC's picture
Online
Last seen: 12 min 2 sec ago
Joined: 03/31/2013 - 05:23
Posts: 1979
Location: AU

Very epic build with great results Beer

kevinthefro wrote:
EasyB wrote:
So each LED is getting 2A?
Correct! Max drive current for the XP-G3.

You might want to take a look here. They top out at around four times that current.

Maybe a driver upgrade will be in the works Wink

Welcome to BLF!

-X3-
-X3-'s picture
Offline
Last seen: 57 min ago
Joined: 07/16/2014 - 03:28
Posts: 1684
Location: France, Angers

FmC wrote:
Very epic build with great results Beer
kevinthefro wrote:
EasyB wrote:
So each LED is getting 2A?
Correct! Max drive current for the XP-G3.

You might want to take a look here. They top out at around four times that current.

Maybe a driver upgrade will be in the works Wink

Welcome to BLF!


Heatsinking would then be a problem…
I think that 2A is a good conservative choice Smile

"Hey -X3-, do you have a flashlight ?"   "-X3-, can I borrow one of your flashlights ?" 

My Flashlight public album (mods, emitter swaps, eye candy)

My reviews channel (French language, Olight, Thorfire : 30+ lights tested)

My personal channel (including Olight SR mini, S1, S2, S1A and S-mini disassembly)

FmC
FmC's picture
Online
Last seen: 12 min 2 sec ago
Joined: 03/31/2013 - 05:23
Posts: 1979
Location: AU
X3 wrote:
Heatsinking would then be a problem… I think that 2A is a good conservative choice Smile

For sure, but a more capable driver with several output levels would be interesting.

…just keep the speed up on the highest level for forced cooling Cool

kevinthefro
Offline
Last seen: 5 hours 9 min ago
Joined: 07/25/2017 - 17:44
Posts: 26
Location: Torrance, California
FmC wrote:
You might want to take a look here. They top out at around four times that current.

Wow I wish I’d seen that earlier! I didn’t know the spec’d drive current could be exceeded on a continuous operating basis. The drivers will go to 3A with a sense resistor change. The heat sink will probably be insufficient, but I’ll set up a test and find out. I might be looking at excessive losses in the 14ga 12ga wire from the battery too.

DavidEF
DavidEF's picture
Offline
Last seen: 6 hours 32 min ago
Joined: 06/05/2014 - 06:00
Posts: 5175
Location: Salisbury, North Carolina, USA
kevinthefro wrote:
FmC wrote:
You might want to take a look here. They top out at around four times that current.

Wow I wish I’d seen that earlier! I didn’t know the spec’d drive current could be exceeded on a continuous operating basis. The drivers will go to 3A with a sense resistor change. The heat sink will probably be insufficient, but I’ll set up a test and find out. I might be looking at excessive losses in the 14ga wire from the battery too.


Yeah, you could probably increase that wire size several gauges higher, and go ahead and up the current to 3A max. Since you’re using DTP copper MCPCB’s I don’t think that would be a problem. But then again, I could be wrong. I’m looking forward to results from your testing! Party

Reason is not automatic. Those who deny it cannot be conquered by it. Do not count on them. Leave them alone.
-Ayn Rand

JamesB
Offline
Last seen: 11 hours 32 min ago
Joined: 08/24/2011 - 14:43
Posts: 708
Location: France

Thanks for posting, build threads are the best Crown

vwpieces
vwpieces's picture
Offline
Last seen: 46 min 47 sec ago
Joined: 07/17/2016 - 19:49
Posts: 1794
Location: PA, USA

That is pretty darn AWESOME.
Very nice work. You have plenty of heat sinking to drive those emitters pretty hard.

kevinthefro
Offline
Last seen: 5 hours 9 min ago
Joined: 07/25/2017 - 17:44
Posts: 26
Location: Torrance, California
X3 wrote:
Did you have any problem with the russian drivers ?

No. Build quality is good. All worked. I fried two playing with their PWM hookups, but that was my fault. I ordered three batches. Took about 4 weeks to deliver each time.

http://www.ebay.com/itm/5-pieces-LED-driver-LD-3A-3A-12V-DC-5V-27V-for-CREE-XHP50-XP-L-XM-L-L2-/112461382388?hash=item1a2f3882f4

kevinthefro
Offline
Last seen: 5 hours 9 min ago
Joined: 07/25/2017 - 17:44
Posts: 26
Location: Torrance, California

EasyB wrote:
Offroading looks like a fun way to get out in nature and a great way to mount powerful LED lights!

Are you also interested in powerful handheld lights?

Not yet. Many projects in the queue still.

Actually I think the vertical beam angle could be narrower. I’d like less light on the ground in front and more in the distance, so I bought some XQ-E Hi emitters to test. With the same lenses, they should get more Cd per lumen and the vertical should decrease from 13 to 8 degrees, per Carclo.

This bar might be obsolete very soon.

J-Dub74
J-Dub74's picture
Offline
Last seen: 6 hours 20 min ago
Joined: 03/14/2015 - 17:17
Posts: 2175
Location: Michigan

Man what a sweet build!
Welcome to BLF. I can’t explain how but someone reading here certainly can tell you how to set up your high beam vs. El Jefe shots either as an alternating GIF or even cooler is the hover-over trick so when you hover over it with your cursor it switches between high beams and El Jefe. It doesn’t matter if you do that or not it just sounds cool. Anyway, well done. I love the stealth factor. That straight on shot looking into it looks awesome. Looks literally like one solid bar of light. Thumbs Up

tjeret
Offline
Last seen: 4 months 3 weeks ago
Joined: 11/18/2014 - 07:12
Posts: 107
Location: Indonesia

It’s long, thin and cute Love
Awesome work
Thank you for sharing

srs2000
Offline
Last seen: 1 month 4 days ago
Joined: 04/04/2017 - 03:09
Posts: 65
Location: United States
J-Dub74 wrote:
Man what a sweet build! Welcome to BLF. I can’t explain how but someone reading here certainly can tell you how to set up your high beam vs. El Jefe shots either as an alternating GIF or even cooler is the hover-over trick so when you hover over it with your cursor it switches between high beams and El Jefe. It doesn’t matter if you do that or not it just sounds cool. Anyway, well done. I love the stealth factor. That straight on shot looking into it looks awesome. Looks literally like one solid bar of light. Thumbs Up

Like this:

You can use https://ezgif.com/maker

southland
southland's picture
Online
Last seen: 1 min 33 sec ago
Joined: 11/04/2012 - 07:15
Posts: 2915
Location: Georgia, USA

Nice light and some good welding.

SoCalTiger
SoCalTiger's picture
Offline
Last seen: 6 hours 44 min ago
Joined: 03/16/2017 - 14:06
Posts: 400
Location: Southern California

Wow this is super sweet.

kevinthefro
Offline
Last seen: 5 hours 9 min ago
Joined: 07/25/2017 - 17:44
Posts: 26
Location: Torrance, California
J-Dub74 wrote:
I can’t explain how but someone reading here certainly can tell you how to set up your high beam vs. El Jefe shots either as an alternating GIF or even cooler is the hover-over trick so when you hover over it with your cursor it switches between high beams and El Jefe. It doesn’t matter if you do that or not it just sounds cool.
srs2000 wrote:
You can use https://ezgif.com/maker

Great idea! Done and done.

J-Dub74
J-Dub74's picture
Offline
Last seen: 6 hours 20 min ago
Joined: 03/14/2015 - 17:17
Posts: 2175
Location: Michigan
kevinthefro wrote:
J-Dub74 wrote:
I can’t explain how but someone reading here certainly can tell you how to set up your high beam vs. El Jefe shots either as an alternating GIF or even cooler is the hover-over trick so when you hover over it with your cursor it switches between high beams and El Jefe. It doesn’t matter if you do that or not it just sounds cool.
srs2000 wrote:
You can use https://ezgif.com/maker

Great idea! Done and done.


Nice!

Way to take advice and go beyond. Thumbs Up

The smooth transition is a very nice touch. Thumbs UpThumbs Up

amplificus
amplificus's picture
Offline
Last seen: 2 hours 28 min ago
Joined: 12/10/2015 - 10:58
Posts: 78
Location: SoCal

This is truly awesome! I’ve been wanting to do some DIY lightbar for a while now with all the available options being extremely expensive or just plain crap.

Do you have a link for the optics?

Pages