High power LED bike head light with integrated heat sink

For those of us traveling by non-motorized conveyance (bicycle e.g.), visibility is important in both forenoon and post-twilight conditions. The best way to ensure such visibility is through the use of excessively bright lights, of which the latest light emitting diodes (LEDs) are the acme. The following account will detail the process of building an LED based head-light capable of of more than 500 lumens of output using about 6W of electrical power. For comparison, this is the same output as a typical 45W halogen bulb.

Step 1: Bill of Materials

The high powered LEDs used for this Instructable are very efficient, putting out 80-90 lumens per watt, compared to typical incandescent and halogen bulbs. However, they still generate a lot of heat and the lifetime of the LED will be adversely affected by high junction temperatures. Therefore we want to get the heat away from the LED through ensuring good thermal contact with the LED board, high thermal conductivity in all materials, and good coupling of the thermal energy to the surrounding medium (air). The LED star board used for this project has three LEDs on it and has a metallic backplane that is isolated from the LED electronics. This is a good thing. The rest of the LED head-light is built out of copper fittings from the local hardware or home improvement store. To complete the project you will need:

Parts:
Luxeon Rebel Endor star 3-up LED
Endor star lens
Buck Puck constant current LED driver
3/4" Copper Pipe Cap
1" to 3/4" Copper pipe reducer fitting
Waterproof connector of your choice (I use 2 position automobile trailer connectors)

Supplies:
Conductive epoxy (thermally or electrically)
JB Weld or similar high strength epoxy
RTV silicone or epoxy for waterproofing
Silver solder and flux
emory paper for cleaning copper

Tools:
hacksaw
drill and bits
file
propane blowtorch
vice
hammer
sandpaper

Comments

[michael.su]

Hi Jon, I finished the Housing....just have to add thee electronics now :-) Thought you might like to see pictures..... More pictures to come when it's all together. Thanks again for all the help. -Mike

[jmengel]

Wow, looks nice. I wonder if there is enough material and surface to adequately cool the LED. I would consider reducing the drive current from 800mA to around 500mA by changing out the resistor on the board. No way to know for sure until you try it and see how hot the housing gets. I know that mine gets really hot (barely can hold your hand on it) at 700mA if you are standing still but does OK when riding and is getting some convective cooling. Yours looks like it has more thermal mass to it, but similar surface area. Let us know how it goes. -Jon

[michael.su]

Hi Jon, I just figured I'd post an update on my light. I've been running it for about 9 months now with no problems at all. It's been completely reliable so far. I get at least 2 hrs of light with a full charge out of it and have yet to run it dry. As far as the heat is concerned.... The extra thermal mass seems to make a huge difference for my light. It barely get's hot at all! Just slightly warm. If you remember, I'm only using 2 of the 3 LED's on the board. because of my battery selection I did not have enough voltage to drive all 3 LED's. (7.2 V 3300 MAh Nimh) That being said, I am running them dangerously close to 1000 mA so they are pushing a lot of light. so far so good (knock on wood) Regarding the optics, I also think the beam is a little too wide for my trail riding. on the other hand my buddy has a light that is too narrow. I definitely need something in the middle of the two. Well, I was googling for new optics since LED supply had no new offerings and I came across this: http://www.luxeonstar.com/Carclo-18-Deg-Tri-Lens-With-Holder-p/10507.htm At 18 deg, I think it may just be the sweet spot I'm looking for. I ordered 2 and will let you know how it goes. -Mike

[michael.su]

never mind on the 18 degree lens. It will ONLY fit on the the luxeonstar boards. you will have to purchase their 3-up board in order to use that lens. it does not fit on the LED supply board. different LED spacing :-(

[jmengel]

Glad to hear that everything continues to work well. Thanks for the tip on the optics, I have been looking at doing a Cree XPG star based light that will have a 16.4 degree optic. I agree that for trail riding the rebel 3-up optic that LED supply sells is too wide, but for city riding and visibility it is great. Keep up the good work. -Jon

[michael.su]

Thanks, I thought about machining some fins into it but didn't have the time. I guess I could still groove it if I need to. or attach a heatsink to the top. I also added screws to hold down the Star so I don't have to pot it just in case I burn it out and need to swap it. I am going to put some heatsink grease under it to help with the thermal transfer. Which resister would I need to change?

[hydronics]

check it out..... I used an Epoxy mold that allows for side lighting... or 180 degrees of light.
http://www.instructables.com/id/Bike-Light-2011/

[Seezor]

I've made this and I like it.  Easy to make and use.  Very simple mounting.  The only thing I did not like was the light itself.  Not knowing I got the one you suggested and it just does not do it for me as far as a good beam.  I will be making another to be helmet mounted using this led.
http://ledsupply.com/creexpg-w417.php
When I talked to a person at LED supply, he told me this was their latest and greatest and has a few different selections for optics.  I've done a dual mount side by side using these and they are very good.  Using your design I've also done side by side tubes Bike mounted I call my Double Barrels using these
http://ledsupply.com/luxeon-leds.php
I like these also because of the selction of optics I get a better beam.  Thanks for your design and I look forward to making more
One other thing I did was to mount my Buck puck on the battery housing which sits in a top tube bag near the handle bars.  No reason for that except not confident enough to square out the end of the tube.  CS

[jmengel]

I've been working on a design with the CREE XPG, it looks like a great LED way better (30% or more) than the Rebels.  The optics choices for the XPG star are also great as you discovered.  The XPG and optics are a little smaller than the Rebel stars and will make centering and sealing a little trickier, but worth the upgrade.

Thanks for trying these out and check out my newer design (still about 9 months old) below for a cleaner looking housing. 

http://www.instructables.com/id/Improved-high-power-LED-bike-head-light-with-integ/

[peterlonz]

Good detailed instructable.
IMHO the soldering processes are a bit difficult & I suspect the junction temp may be right on the limit ,although even if it should cut the life by 80%, I suppose that's no matter really.
Problem as always is getting a conducting medium to get the heat away & I am not keen on conducting epoxy.
I wish you could hurry the update, I bet you have some real improvements to show us.

[jmengel]

Barring getting the Rebel LED chips and building your own heat sink and PCB combo, the star boards are the only game in town.  Do you have any ideas?  I've got no data to show that the LED junction temp is too hot, and have seen no failures.  That said, the light has less than 1000 hours on it.

If you look at the thermal conductivity of stuff that you could realistically put between the PCB/star and the heat sink there is not a product out there that is better than a conductive epoxy.  Conductive epoxies contain conductive particles, and outside of Aluminum Nitride and diamond, the best thermal conductors are all electrically conductive.  The difference between a thermal and conductive epoxy is the amount of solid filler.  The electrically conductive epoxy is loaded past the so-called percolation threshold and therefore has reduced resistance (both electrical and thermal).  The advantage of the isolated backplane of the star board is that you can use a conductive epoxy which has a higher solids content and therefore higher thermal conductivity.

BTW, the new doc is up.

[michael.su]

I'm also looking forward to it!

[jmengel]

http://www.instructables.com/id/Improved-high-power-LED-bike-head-light-with-integ/

[MACKattacksnipe]

steam punk-ish

[wiredcur]

Looking forward to it!!

[baratacus]

You don't want to blind other people on the road with you.  Not only will you make motorists angry and endanger people by blinding them so they can't see, but you can be ticketed and fined for opperating a vehicle in a hazardous manner.   The flood light is great for off road applications where you need to see rocks and chuckholes, low branches... but for on-road, you need a focused beam for a light that intense.
It's the same reason  that motorists who put HID xenon lights in a normal lamp housing without a focusing lense get fined and ticketed.

Excellent headlight option.  Once focused, you can probably go with a less powerfull setup and your battery pack will last longer.  Lithium is the way to go for high power output in a small size.

[jmengel]

I disagree.  As a cyclist in a world built for cars I want to be seen. The brighter and more splash the better to increase visibility. I'm not advocating a blinding sun-like beacon but I can't see how the 25+ degree lens on my light is any more blinding than the headlights on any truck or SUV at eye level to a motorist in a car.  I've ridden with people who have lower powered and tightly focused LED bikelights and while they have a nice throw out to 100+ feet they are surprisingly invisible to oncoming motorists outside that 10 degree cone.  I prefer to see as well as be seen.  Case and point my latest tail-light project has 100+ lumens of wide angle (160 degrees at 50%) light which is way better than the common LED blinkies with a 15 degree pattern.  How many times have you come up in your car on a cyclist with one of those anemic red LED flashers clipped to their black backpack and pointing the wrong way so as to be practically invisible?  Really common around the colleges here and on the sidewalks which is a recipe for disaster.

Lithium batteries are certainly superior in terms of energy density.  My latest light has a low and flash mode which extends the battery life of the LiFEPo pack significantly.  Like the aforementioned tail-light project, I have been meaning to write this up in an Instructable but have not found the time or energy.

Stay safe!

[baratacus]

I agree that visibility is an issue, but putting out 600lm of light in an unfocused beam, That lamp puts out way more light than the 60 watt incandescent bulb in your photos.   If it's as bright as you indicate then that is an issue.  My car has old-school seald headlights and it puts out less light with the highbeams on than that LED light you built.  If that light wasn't focused it would blind anyone looking at it.  You would be visible, but the motorists wouldn't be able to see anything else after they were night blinded by your light.    If you want more visibility then a multi directional lower output light would be a good start. I think the 100 lumen tail light you mentioned sounds perfect, and would do good as a front marker light as well.  In california though, on-road, you would be fined for running a 600 lumen  light  without focusing it.

[jmengel]

Uhh, and keeping wildlife, an amphibious rodent, for uh, domestic, you know, within the city - that ain't legal in CA either. (Walter)

Standard halogen headlights perform in the 15 lumens per watt range.  Typical low beams are 45W and high beams 65W for roughly 700 and 1000 lumens respectively.  Sealed beams have compromised reflector designs but still put out a lot of light.  Just more spill.  So with your high beams on, your old school headlights would be putting out 3400 lumens total L and R.  Which is brighter?  Now if were talking a padiddle all bets are off.

http://www.sylvania.com/ConsumerProducts/AutomotiveLighting/Products/Halogen/StandardHalogenProducts/

Additionally, I think you are confusing the lumen rating and candela rating (http://en.wikipedia.org/wiki/Candela).  A 600 lumen light with a 10 degree lens would appear much brighter than a 600 lumen light with a 25 degree lens.  The focused light would have roughly 6 times the candela rating and be 6 times as bright.  As to which impinges more light onto an oncoming driver's eyes is a complicated function of the optics of the systems in question and the emission pattern of the LED arrays as well as the aiming of the lights. Similarly, the poor reflector of a sealed headlight and the broad spread of the design in general may make them seem dimmer (low candela) than a focused LED but the headlights are still putting out a heck of a lot more light than the LED bike light.

So let's just agree to disagree and I promise not to ride with my light in CA.

[baratacus]

I don't dissagree at all.   The police here in my city are ticket happy when it comes to unfocused headlights.   They are'nt very concerned when it comes to satndard bike lights because they don' t typically put out more than 50 lm's of light.  I think a flood will provide you with much more visability than a spot.  I think with your light it may require some focusing for the law enfrorcement  officers to be ok with it.   That of course is pure speculation based on the sample pictures you provided.   Personally I intend to make one of your lights for myself, cause it's just too damn cool a project not to build.   When I do, I'lll be able to see first hand whether or not focusing the light is a concern.   focusing the light  is a very simple matter, and if I do feel it's necessary it will be pretty easy to shape the beam. 

[jmengel]

If you plan on building, I'd say wait a bit until I get the latest instructions ready as the latest light design is much improved.

[speeddemon2008]

Thankyou so much for making this! you have inspired me to make one so I did. I made it last spring and have enjoyed ever since. I ended up using a cree M-CE led.  I then used the thermal paste to glue a 1in and 3/4in pipe cap back to back and followed your directions. I have had fun with the battery pack though, its been a struggle.
My pack consists of 4 18650 lithium cells. I use 3/4pvc for the case. I put a nice screw top on it so the batteries can slide out. And just tonight have I figured out how to securely fasten it to the bike in a way I like. This has been a great project!
The second picture has version 1 of the battery pack...it failed...

[jmengel]

Looks good.  Any problems with the toggle leaking in the rain?

[speeddemon2008]

I have mounted my light to the underside of my handlebars, so the switch is at the bottom usually. I dont even have the back of the case to the light covered. I figured rain isnt likely to come back and hit it from the back side, and I keep my bike indoors. So no I have not had any problems with rain yet... but there is most definitely a possibility since I do live in Oregon, rain all the time. I drive my light at 700ma and it is rated for 740 lumens at 700ma. My friends all say it looks like a motorcycle from head on, and when I ride past someone I often hear "Oh geez, I thought that was a car." I do keep the light pointed down as I do not want to blind anyone, but there is still enough scattered light to illuminate street signs. Im tempted to make an Instructable about my battery pack, for specific use with this type of high draw bike light, and more universally for the 18650 battery cell; what do you think?

[Jr Hacking kid]

I want to make this but...... i have no idea on what voltage to power it. i want to power it with some duracell 2650mah AA battery cause i can get them cheap at my swap meet but.. i don't know  how many  do i have to buy.

Help me out in clueless at the moment Thanks

[jmengel]

Depends on the driver and LED you choose.  The driver used in this instructable requires an input voltage greater than the LED forward voltage.  Since I used 3 LEDs in series I needed to have an input voltage greater than the LED forward voltage at the set current times 3.  Which was 3.4 volts times 3 = 10.2 volts at 700mA.  The driver needs 2 extra volts to run so the input voltage needs to be 12.2 volts or greater to maintain 700mA.  If you used 2650mAh AA alkaline batteries you are going to need at least 8 of them since they are 1.5 volts each and you need 12 volts.  In practice, as the 8 AA lose voltage over time during use, the current output to the LED will drop slightly as the driver chip will not be able to maintain 700mA.  If you use 9 or 10 AA in series to get 13.5 or 15 volt input you will get 700mA for a much longer duration.  The maximum number of alkaline AA cells you can use is going to be 21 cells or 32V.  All this information is available in the LED and buck-puck driver datasheets.

Good luck.

[Jr Hacking kid]

oh they are rechargeable 1.2v 2650mah AA battery so in my case i need 10 of those to get 12 volts right what if i have 12 battery cells will that work also and yea im just going to make it according to your plans i like how it looks and i can just buy all the parts in one place without waiting for the parts  to be shipped all the way from china to hawaii. thanks for helping me.

[dcbrc2]

Really nice job on this: I really wanted to "do it right" using a driver and LED's, this really gets me going.

One question: is there any reason that the buck puck needs to be in the light unit?  The way I'm thinking of doing mine would be more convenient with the buck puck at the power pack.  That shouldn't be a problem, should it?

Thanks,

--David

[michael.su]

Here are my pictures of the fully assembled light.

http://i116.photobucket.com/albums/o8/michaelsu_bucket/Bike%20Light/P9180061.jpg

http://i116.photobucket.com/albums/o8/michaelsu_bucket/Bike%20Light/P9180058.jpg

http://i116.photobucket.com/albums/o8/michaelsu_bucket/Bike%20Light/P9180065.jpg

http://i116.photobucket.com/albums/o8/michaelsu_bucket/Bike%20Light/P9180067.jpg

http://i116.photobucket.com/albums/o8/michaelsu_bucket/Bike%20Light/P9180072.jpg

The battery ran for 2 hrs full power with no problem. Not sure what the total run time will be.
The first trail test will be in a couple of days. :-)

-Mike

[jmengel]

Nice job. Good to see it works.

Update: I've had a chance to tinker around with some of the LED drivers I have laying around. I've found one of the DX drivers I have is a true boost type driver. I've run a Rebel 3-up at >800mA and Vf~10.3V with a 5V source. I've also poked around enough with this circuit to figure out the layout to where I can change both the low and high mode set currents. The circuit comes configured to run pretty hot, with high mode current at nearly 1000mA regardless of what the DX description says. I dropped that to around 600mA and am happy with the output. The strobe mode is nice as well, with current draw <200mA. The strobe is a bit fast but hard to ignore for oncoming drivers as long as no seizures are induced. A bit more pricey but the multiple modes are a nice plus.

http://www.dealextreme.com/details.dx/sku.25516

The above driver is CURRENTLY based on the FP5138 boost IC. No telling how long that will last but after digging around for a long time I was able to ID this chip and make mods to the circuit successfully.

http://www.micro-bridge.com/data/Feeling-tech/FP5138_AN.pdf

[michael.su]

That looks good Jon. Very good price considering how few options there are out there for this application. The multiple modes are not real useful for me, I just like on/off. I pretty much stick to trail riding but at the price, I can deal with it. I can't get the link to the datasheet you posted to work. not sure if they are just having server problems but what did you need to do to modify the circuit to lower the current output?

[jmengel]

The PDF link is slow but still works for me. If you need it I can email it. Send me a private message if that is the case. They sand the identifying marks off of a lot of the ICs on these boards for some reason, so figuring out which IC was used was a pretty big PITA for me but I am happy with the results. I guess they sand off the markings to keep from getting out-China-ed by even lower cost board houses. A race to the bottom.

If you don't like the extra modes you can simply cut away the bottom (battery side) board with the microcontroller, toss it, and apply the battery - wire to the single post and the battery + wire to the middle post of the three posts on the top board (the one with the inductor). The current setpoint will be 250mA in that case. Just need to change out the resistor on the top to get a different current. It is a 2 Ohm as delivered and by lowering it to a 1 Ohm the current will be 500mA. Equation for current is: i=0.5/R Where R is the set resistance.

[michael.su]

update, Using a 9 volt battery instead of my 7.2 nimh I get an ammeter reading of 52 vs the 7.5 reading so the input voltage is directly related to the current. It does not appear that I am getting any voltage boost from the LED driver board. Perplexing to my feeble mind. I took everything apart and wired in the second LED driver board in to rule out damage to the first one creating a problem but the test results are pretty much the same :-( Not sure where to go from here....... -Mike

[jmengel]

I've gone back and looked at my circuits. While the DX site appears to have previously sold ZXSC310 based boards the ones I have are based on a SOIC-8 chip that has its markings sanded off. My guess is that the circuits are similar but without the same board as yours any testing I would do is not helpful. The ZXSC310 board you have should be capable of boosting to the voltages needed to power your 3-Up Rebel star. My guess is that with the increased Vf of the 3-star some of the components are not sized appropriately for stable boost operation. Further, my guess is that the output capacitor is not large enough. Try adding additional capacitance between the LED+ wire and GND (battery negative). I'd add 40-50 uF with a voltage rating of at least 15V. See if that doesn't increase the current output. -Jon

[michael.su]

Thanks for the suggestion. I added a 47 uF (50v) Capacitor. No change in voltage or current. :-( I saw that LED supply offers a "boost puck". looks like it's just what I need. it's a bummer that they are only regulated at 350 mA though......if only they had a 500 mA version. I can't seem to find any other similar products around the net. Have you seen any other LED drivers that are designed to boost voltage? not enough people using this stuff yet I guess....

[jmengel]

In theory there is no reason that a circuit based on the ZXSC310 reference designs should not work unless it is wired as a buck rather than boost config. A way to check would be using a multimeter or eyeballs check to see if the inductor is wired to the pins on the ZXSC310 as shown in all the application examples, from the + battery to the collector on the switching transistor. You can use these wikipedia links to check the topology:

http://en.wikipedia.org/wiki/Buck_converter

http://en.wikipedia.org/wiki/Boost_converter

Are there any markings on the 3-pin IC in the center of your board? This is the transistor and should have a voltage rating high enough to handle the expected boost voltage. Another check would be to monitor the signal on the VDrive pin on the ZXSC310 to see if it is truly switching the transistor and to estimate the duty cycle using an oscilloscope.

[michael.su]

Yikes! I understand the theory of the 2 circuits but can't seem to apply them to the physical board I have :-( If I get you a good quality close-up picture of the board do you think you could tell what configuration it is? or maybe you could link me to a couple pictures of similar circuit boards with the different configurations? The writing on the transistor is "7N3" -Mike

[jmengel]

Probably a photo would provide enough info to make a guess. Go for it.

[michael.su]

ok, here it goes......

[michael.su]

let's try that again.....

http://i116.photobucket.com/albums/o8/michaelsu_bucket/P9150053.jpg

http://i116.photobucket.com/albums/o8/michaelsu_bucket/P9150054.jpg

[jmengel]

From the photos it appears as if there is a solder bridge between the collector on the transistor (the single pin on the 7N3) and the anode on the power diode (SS14). Can you test if they are connected electrically and if there is a trace connecting them or the solder bridge is an error. If it is an error, wick the extra solder away and see if that changes anything. I'm also unable to see fully what is connected to the positive battery lead. Can you test to see what parts are shorted to the battery+ lead? Is LED- (black wire) grounded? If this all sounds like a waste of time, it may be since the circuit looks to be using the ZXCS310 in a buck config. The good news is that the parts are all there for you to change the config to a boost, the bad news is it will require tweaks to the board. From what I can see it would require disconnecting the inductor from LED- and connecting it to battery+ instead, as long as the other side of the inductor is on the anode of the power diode and the collector of the transistor which I can't tell for sure from the photos. Also would need to connect LED- to ground.

[michael.su]

hmmm. Since this appears to be a Buck circuit and after reading the comments on the other boards you linked to on DX , When I receive them they will likely be buck also, I think I might attack this beast from a different angle. It appears to be hard to find a boost circuit with the specs I want / need :-\ I might just disconnect one of the LED's and run it as a 2 up with a buck driver or run 2 of the LED's in parallel. That way I will have enough voltage to drive them without boost. What are your thoughts? I'm going to do some testing tonight to see what gives me the best output.

[michael.su]

Works Awesome! I bypassed 1 of the 3 LED's and it's drawing 950 mA. A little higher than I wanted but, it put's out a crazy amount of light. even at 2/3 the light of 3 LED's there is plenty of light. I'm testing battery life right now.....hopefully it doesn't burn up....LOL The housing does get pretty hot so I set it up with a little fan blowing on it while I test. Doesn't take much to cool it down thankfully. As you posted earlier, I'm sure it will be fine while I'm riding. Thanks again for all the help Jon. I'll keep posting my results and maybe a few pictures of the assembled unit when I get a chance. -Mike

[jmengel]

I'm glad it is working. I'd be careful running at 950mA, the absolute max on the datasheet is 1000mA so you can expect reduced lifetime running at that level. Significant reduction if the heat builds up due to inadequate cooling. I'm going to draw up a true boost version of the board with a more manageable current output and potentially adjustable output. I too have been disappointed by the DX offerings for certain applications and it wouldn't take much to make. Hard to beat the <$2 prices though.

[michael.su]

That sounds great. I would love to have some way to adjust the current on the fly (without trying to solder those tiny surface mount resisters) :-0
someone on the candlepower forum linked me to a driver board that would work . it's boost configuration and the current could be set @ 300,500, 700, 1000 mA settings.
Not in the budget this time around but a nice concept.

here's the link....

http://www.taskled.com/maxflex.html

If I knew where I stood in the beginning, I probably would have ordered this one.

luckily you can teach an old dog new tricks, I have a better understanding of it all now :-)

...............chalking it up to experience

[jmengel]

You definitely pay a price for the low cost of such products from China. No documentation, no support, no guarantees. The prices on the taskled site are not too bad considering the complexity of their boards and the low volumes. They are being made in China as well I would bet. If I were to draw up a simple board, getting it made and then buying the parts for assembly myself would run in the same neighborhood of ~$20. No free lunch. Changing the current on the fly can be accomplished by switching current sense resistors with a selector switch or by PWM with a microcontroller. The first requires soldering (not really that hard at all with a good pair of tweezers and a fine iron tip) and the second requires the expense of additional parts, code, programming, etc.

[michael.su]

Tell me about it! EVERYTHING is made in China. all the mechanical parts I make are eventually made in China too :-( I thought the price was good too. Unfortunately, I'm way over budget. I ordered some parts that I won't even be able to use (for this project anyway) trying to find a workable solution. I will receive a boost puck in a day or so. I don't see how the 350 Ma current could be useful for this. not sure why I ordered it. I guess as to have more options. a selector switch and a bunch of resistors I'm guessing? do you have a picture of this kind of setup?

[michael.su]

It appears that 1 lead on the 310 chip is wired to the inductor. does that sound right?

[michael.su]

The last component on the board appears to be a diode connected in parallel.( the leads out to the LED are connected to this component) looking at the schematic i would say that means that this is a buck board :-( I checked the component in question for continuity and it only has it in one direction (open in the other direction) so I figure it must be a diode. If it was a boost circuit the diode should be in series not parallel right? is there anything wrong with my logic?

[jmengel]

Potentially this would indicate a buck type. But if it is in parallel across the LED+ and LED- leads that is different than a "normal" buck that has the inductor between the diode's cathode and the LED+. Your logic appears sound.

[michael.su]

Hi Jon, I decided to put the light together the way it was and then deal with a heat problem if I needed to. I have the light all together and it turns on but there is definitely a problem. it's not as bright as it should be and it is not getting hot at all. That leads me to believe it is not getting the current it should. I tested it with a ammeter right after the battery and before the LED driver board and it reads 7.5 on a 200 Ma scale. Can that be correct? If so, what could be wrong? any ideas would be greatly appreciated. -Mike

[michael.su]

(removed by author or community request)

[jmengel]

If your circuit is like mine, then there is only one resistor on the board, labeled R020 which is a 0.02 Ohm resistor. To reduce the output current to 500mA (~40%) you need to increase the resistance to R032 or 0.032 Ohms or thereabouts.

[michael.su]

ok. I have all my parts in and I'm a bit stumped.......Not a tough feet I know ;) the wire leads that are pre soldered to the driver boards, are they the "in" leads from the battery or the "out " leads to the LED? that brings me to the next question.......Where do the other leads get soldered? The bottom of the board since it has an outer and inner isolated copper trace? sorry for the dumb questions but i have a very steep learning curve :) Thanks, -Mike

[jmengel]

If you are talking about the flashlight LED driver, then the inner copper circle on the bottom is the + from the battery and the outer copper ring is the - from the battery. The two wires soldered onto the board already (black and red I believe) go to the LED, with the red going to the +LED and the black to the -LED spots on the LED star. Put the switch (if any) between the + battery line from the battery and the inner copper circle +battery input on the board. If you have a connector between the battery and the board you can just unplug the battery rather than use a switch. -Jon

[michael.su]

Hey Jon,

I figured the battery connections out before I saw your return post.
Yes, I am using a flashlight driver. The one you linked to is on back order so I found a replacement with the same specs locally. This is the one I have:

http://www.shiningbeam.com/servlet/the-40/Circuit-board-1160/Detail

I checked the circuit and it appears to work to some degree. The LED lights up but I have doubts that it is being fully utilized. I don't see is the voltage "boost"
I hooked up a 9V battery to the LED driver board and with a volt meter I get the same voltage coming out of the board as I do going in. Is this normal without having a "load" connected?
In this case the load being the LED's.

On the bright side ( pun intended) I am learning quite a bit here.

-Mike

[jmengel]

The circuit will not work correctly without the load (LED) connected as the purpose of the circuit is to modulate the output voltage to maintain a constant current through the load. In fact some circuits will be damaged by running them without the LEDs connected. I'm not sure what the specs are on the circuit you linked to but it certainly looks similar to the one I used. Hook up the LED to the drive circuit with your meter in series setup in high current measuring mode to check the current drive through the LED. It should be near the 800mA specified. Can you read the labels on the ICs on your board? Look for one labeled C300 or C310.

[michael.su]

I guess I will have to put it all together to know for sure if it is working correctly :-( I didn't want to put power to the LED board for a long period of time while I take measurements because I have not built the chassis/heatsink yet. I was just making sure I understood the circuit first. There is one IC that is labeled C310 on this board.

[michael.su]

Thanks for your quick reply... as you probably figured I'm a "mechanical guy"
electronics are not my strong point. That's why I was looking to use your circuit.
What do you mean by "boost Circuit"?
The flashlight drivers are at a great price.
What voltage would be required for it. As everyone else is I'm working on a limited budget here otherwise I would just copy your setup exactly. ( I may in the end anyway just would like to know how this all works )

I have a couple of batteries similar to these laying around with a charger that I was thinking about using:

http://www.trademe.co.nz/Toys-models/Radio-control/Parts-accessories/Batteries/auction-239267008.htm

I could put one in a water bottle or something like I've seen with other batteries.

What components do you think would best utilize them?

Thanks again,

-Mike

[jmengel]

Boost means that the driver circuit generates a drive voltage for the LEDs at a higher voltage than the input battery. The driver I used in the example is a buck circuit, meaning that the drive voltage for the LEDs is lower than the input battery. The battery pack requirements of the two types of drivers (boost/buck) are different, depending on the forward voltage of the LED string. For example, 3 rebel LEDs in series have a forward voltage of 10.2V at 700mA (slightly less at 350mA). For a buck type driver you need to make sure the battery voltage is greater than the forward voltage by an amount specified in the spec sheet for the driver. Typically by 1.2V or more. So I would need to keep the battery voltage above 11.4 if driving at 700mA. Similarly, a boost circuit requires that the battery input voltage be less than the forward voltage by a set amount, such as keeping the pack voltage below 9V. To answer your question, the battery pack you linked would work in a boost type driver if you were using a string of series LEDs with a forward voltage above the battery voltage which is typically the case in flashlights so the flashlight driver is the better choice in that case. The specs for the flashlight driver I linked to indicate that at least 3.6V are needed and that up to 9V can be used. I would stick to the 7.2V or less packs for efficiency sake.

[michael.su]

Would the 3 LED star you chose work in this boost configuration with my battery? It is wired in series in your design correct? I would think I would lose a percentage of light and run time with my battery but how well do you think it would work? I trail ride at night often and I have a cheap $25 light now which is definitely not enough.

[jmengel]

The 3 LED star ships from LED Supply wired in series and would work in a boost configuration with the 7.2V battery and flashlight boost circuit.

The efficiency of the boost circuit (link below) on the flashlight circuit I linked to is >90% at higher supply voltages so you will NOT lose runtime or light with your chosen battery. For example, the 7.2V 3.3Ah battery you linked to has ~24Wh of energy in it. Running the 3 LED star at 800mA and Vf of 10.3 will consume 8.24W and output about 600 Lumens running for somewhat less than 3 hours. 600 lumens is a blinding amount of light, approaching car headlights so should be plenty.

I would tune the current down to about 500mA personally by changing out the resistor on the circuit board to a 0.04Ohm based on the data sheet linked. This will reduce the heat sink requirements, as well as increase the LED and battery lifetime. Good luck.

http://www.diodes.com/datasheets/ZXSC300.pdf

[michael.su]

Everything is ordered. I can't wait until it all comes in. thanks for all the help. I'll let you know how it goes and maybe post some pictures.

[michael.su]

jmengel. looks great. looking to build one myself. I'm a machinist so I may make my own Housing from raw 6061Aluminum. Do you have a link for the alternative LED driver on deal extreme you posted in your material prices update. I can't seem to find anything on there with similar specs. Thanks!

[jmengel]

http://www.dealextreme.com/details.dx/sku.13557

The above is geared towards 12VDC or 12VAC halogen bulb replacement but you can bypass the diode bridge if using a 12VDC battery and desolder the MR16 "bulb" pins. You are left with a compact, constant current driver with pretty high efficiency (>90%). Regardless of what the specs say, the boards I got (3W) were set for ~650mA output and can be changed by swapping the current set resistor. The circuit will drive 3 LEDs in series if your supply voltage is high enough, the limitation being thermal shutdown of the driver chip. If I recall correctly, I've gotten both PT4105 and PT4115 chips on my boards depending on batch. See below:

http://www.zhaoming.com/bbs/u/2008/07/01/13021214907053.pdf

If you want to run a boost type circuit, look for the flashlight driver boards on DealExtreme. Many of them are not constant current, so read the forums and reviews. I've had good luck with the one linked below:

http://www.dealextreme.com/details.dx/sku.3256

[j-plan]

hi jmengel, firstly great instructable :) secondly im looking at a water bottle battery from batteryspace.com the "Water Bottle Nimh Battery: 12V 4500mAh (50W) with Trail-Tech Female plug " could you tell me if this would do the job? thanks

[jmengel]

Yes this battery would do the job and then some. At 50Wh capacity you can expect somewhere around 7 hours of runtime at 7W output from the LEDs (10.2Vf and 700mA drive). Thus you could get by with a lot less battery in most riding situations. Good luck.

[potatoesforsale]

(removed by author or community request)

[jmengel]

Use a different drive circuit. See the link below for a cheap constant current drive circuit that can run off of 3.6V to 9V. The current output is pretty high, rated at 800mA, but I have measured more like 950mA on a 3-up rebel star. You can change the set current by changing a resistor on the board if desired.

http://www.dealextreme.com/details.dx/sku.3256

[potatoesforsale]

thanks, I about gave up before you responded. I want to make these for people but if I could run them on AAA it would be much easier. none of my friends have $200 batteries.

[jmengel]

Or $30 LiFePo battery packs. Good luck.

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=3794

[discontinuuity]

Looks like a cool project. Approximately what was the final cost?

[jmengel]

$15 for the driver $28 for the LED $5 for the lens $5 for the copper $2 for the connectors Glue and solder was on hand So the total is about $55. The battery can be a significant portion as well. I already had some on hand so that was not a factor. A 12V 1350mAh Fe-Po lithium pack will run about $30 and another $25 for a good charger. If you want to use alkaline, you need 10 cells in series, and from Costco that would be $8 or so and would last about 3 hours. A sealed lead acid would be in the $15 range but heavy.

[jmengel]

Update: The LED's have come down in price significantly, and cheap (~$2 ) driver circuits are available from Deal Extreme which do not have dimming or flashing capabilities built in but can be modified to. Total cost using these new prices: $2 for the driver $16 for the LED $5 for the lens $5 for the copper $2 for connectors Total: $30 Not bad.

[Califflorida]

Is this thing daytime visible?

[jmengel]

Almost as daytime visible as headlights. The average lowbeam halogen car headlight is putting out around 1000 lumens. The optics, spread, and emitting area are different so the actual "visibility" to the naked eye in a daylight environment will be subjectively different. Daytime visibility will be improved if you use a buckpuck driver with a control pin and a 555 timer based flash circuit. I can tell you that the picture above taken with the LED light on the bike in Step 8 was taken in the daylight (an overcast day) and drowned out the daylight in the image as can be seen. In summary, I think this is daylight visible, and could be made more so with a flash option.

[Califflorida]

Thanks!

[llouy4151]

hi, can you tell me where you bought your led the cheapest i have found it is $38, and as a am in the uk with shipping this is alot of money. ps have you looked at lumicycle.com they are good for ideas and spairs

[jmengel]

It has been suggested that DealExtreme.com is a good source for LEDs, but their selection is kind of limited. If you want Cree LEDs in cool white, they are a good source with rock bottom prices. They also have great deals on driver circuits that are bare, as in not potted, for $3 USD. Which is a steal.

[Califflorida]

Can you show us beam shots out on the road?

[jmengel]

I'm working on it, see Step 9 for some indoor beam shots.

[Califflorida]

If it lights up the road well, I'm gonna put 4 on my bike.

[jimbo333]

your gonna need alot of battery power for four of them, you should try to make a battery pack disguised as a waterbottle, its an idea ive wanted to use but i dont need it as i use a police tactic flash light for my bike most of the time.

[jmengel]

You can buy water bottle batteries from:
Battery Space

[jmengel]

Oops, you would need less than 10 alkalines in series, they run 1.5V per cell so you could get by with 8 instead of 10. With the buck puck running more cells in series your runtime is improved as the total current draw decreases with increasing voltage, with some consideration for varying efficiency of the step down circuit at different input voltages.

[Jarl]

yikes, don't use alkalines for a bike light. Poor cold weather performance, poor capacity under half decent load, and costs quickly mount up. Also, while NiMH run at 1.2V per cell under load throughout discharge, alkies start off at about 1.5 then drop rapidly, especially under high load. They still have a lot of power left at 1.1V; so I don't advise you use 8 alkalines unless you want to dramatically reduce battery life from what it could be. Did you hear about the luxeon rebel recall? Due to some dodgy epoxy, there's ~20% chance each LED will fail within the first 24 hours of use. I had one of mine do this on my bike lights :(. Hopefully you'll fair better.

[jmengel]

Hmm, hadn't heard about the Rebel LED recall. I have yet to have any problems, but I don't think I've hit the 24hr runtime yet. Have to wait and see, thanks for the heads up.

[fabelizer]

Very nice! Great job on the instructable. Where did you get your LED and lens? Any info on length of run on a given battery? -fab

[jmengel]

See Step 1.

Run time depends on a lot of factors, for rough guess divide battery WattHrs by LED wattage. For example, 12V 2Ah= 24 Wh and 2.4hours runtime at 10W.

[hpfev]

Is it possible to use a bike dynamo instead of a battery pack as power source?

[jmengel]

Yes.

[hpfev]

do u have any specific one that you recommend?

[jmengel]

The Sram i-Light Generator Hub is one option. I have never tried a generator hub but I have heard that they are much nicer and less of a drag than the old friction style. Typically the hubs are 2.4 to 3W output so you can't really get the full light output possible with 3x3W LED array. However, you could run the 3 LED star shown above at a lower current or figure out a way to alter the output of the generator hub.

[hpfev]

Thanks for the reply. Do you think it would be better to run the 3 up leds at lower current or go for a 1up led? And another question, what was the conductive epoxy that you used to glue the led to the copper?

[jmengel]

You get more light per power input with a lower current. So running 3-up LED star at 1W per LED will give you more light than 1-up LED at 3W. The difference will be small, with the single LED giving around 85-90% of the light of the 3-up for the same input power. The main difference will be cost. For example, a 100 lumen 1-up star is ~$15 and a 300 lumen 3-up star is ~$37.

The conductive epoxy I used is http://microcenter.com/single_product_results.phtml?product_id=0210267

[mrmees]

Was looking over at the LEDsupply website and was wondering.

If you were redoing this project now, would you go with the micropucks instead?

http://ledsupply.com/micropuck.php

[jmengel]

I would not. The micropucks do not pump out enough current, topping out at 500mA. For some apps this would be fine, but I wanted 700mA.

[RiddleOfSphinx]

Looks like it would make a half decent projector light. I might have to try this when my bulb burns out....lol

[jmengel]

The key to a good projector light is uniform brightness and good color rendering. I'm sure you could make an LED projector light that would be bright enough, but the CRI may not be up to snuff and the uniformity would be challenging.

[krapez]

Man, this things really get hot. And I mean really HOT. So hot, that You can easily burn your skin on it... It is necessary to put some cooling stuff on it - as an addition. (like Obdave suggested some comments back). Diodes also might get damaged by overheating. Otherwise the light shines beautifully. Very bright, ideal for bikers, maybe not for use on traffic streets - too bright... Thanks to uploader !!

[Rainbowlaces]

Really great instructable! I've been looking to make a headlight for awhile now, and this has some awesome ideas. Have you figured out how long you can run the light with the LiFePo? 2 hours probably isn't long enough for what I would use it for. THANKS!

[jmengel]

Runtime varies depending on a lot of factors. In the case of more advanced battery packs with discharge protection, the allowable final voltage is controlled. My packs do not have this feature which can extend pack life. Assuming a non-dimmable LED light and a constant current drive you can run the LED light until the pack voltage drops below the capability of the drive to overcome Vf of the LEDs. In practice, the drive current will decrease as the pack voltage drops. In my case, I am willing to accept reduced output if I need more runtime than the pack can provide at full power. I have never run the pack to full shutdown so can't comment, but it is larger than 2 hours. If you need more runtime, build or buy a larger capacity pack. Simple as that.

[Rainbowlaces]

Thanks for the info! I will keep that in mind when (if I can) start this project.

[disturbedreaper]

srry coldent spend much time reading all this so if the answer is around somewhere sorry for the troble just let me know but do yo think i can replace the head lights on my go-kart and run these straight from the 12v batter(very simmilar to a car batter just a tad smaller) thanks in advance

[jmengel]

Yes you could hook this light up to a 12V go kart battery, as long as you use the buck puck driver circuit.

[disturbedreaper]

thanks ill give it a shot when i have more then 3 dollars in my wallet

[obdave]

Thanks for posting this instructable, i really appreciate it. I bought the parts and built the light as you've described, but I made two changes worth mentioning: 1) Instead of relying on the silicone caulk/rtv for waterproofing, I bought a 1" copper plumbing cap and capped off the back end of the light. Rather than solder it, though, since the electronics are already inside at this point, I just used the thermal expoxy to glue it on. 2) Boy this thing gets hot. So I went to a hobby store and bought a heatsink for an electric motor. You can get these in a variety of sizes. With a little bit of help from Mr. Dremel it just snapped right on. Again I used the thermal epoxy to hold it in place. I've attached photos of the assembled light, and also a photo comparing an ordinary $20 5-LED bike light (left) to this Instructable (right). No trickery here, I used the same f/stop and shutter speed for both photos.

[jmengel]

Looks great! I like the look of the assembly with the 1" cap. What electronics are you using in order to fit in the 1" copper section without hammering? I think I will get some heat sinks myself once the weather warms up. Thanks for sharing your project.

[obdave]

Thanks! Oh yeah, I forgot to mention this! It's not necessary to hammer the 1" section of the pipe fitting if you put the Buck Puck LED driver in endwise. Mine is a 700 mA driver from the same source listed above, and it just slipped right inside without any modification required. I just put it in, added a bunch of silicone goo, and then cemented the cap in place. Very easy and very solid. It's pretty heavy, though. There's a lot of copper in this little light. For a mount, I went to the LBS and they gave me a couple old reflector brackets, the kind that normally goes around a seat post. One goes around the light and one goes around the handlebar. The two are at a 90 degree angle with an aluminum standoff tube to separate them. I deviated from the instructable in one other place. I didn't bother cutting back the 3/4" section of tube at all. This light has such a wide beamwidth even with the lens in place that I figured it was better to have a little extra tubing in front to cut down on the amount of light scatter. It still casts a very wide beam.

[jmengel]

Cool, I thought I tried to fit the buck puck in all possible ways, but maybe I got tunnel vision. If all you have is a hammer, everything starts to look like a nail. I imagine adding the 1" cap does increase the weight somewhat. The o-ring mount I use does pretty well, I have yet to have it shift on me. We'll see if that holds true with added heat sink. Really glad to see the idea built on and improved.

[david_]

From your pictures It looks like there are two surface mount resistors connecting the individual leds in series. I didn't see anything in your text about these though. What are they? Resistors or just anything to connect the two contacts. Thanks

[jmengel]

Those are 0-Ohm shorting jumpers packaged in the 0805 SMT package. They were included on the Endor Star as purchased. Without them you can power 3 LEDs independently for an RGB light for example.

[stevers]

Is there a problem with running this rig on less than 12.2v? I'm not ready to shell out money for a lifepo pack or 10nimh and chargers. Instead, I want to use readily available 9.6v nimh RC car battery packs and charger (~$30 for both). It's also easy because most of these batteries and chargers come with tamiya connections, which cuts out a step or two to fashion some connecting devices. My plan is to make a few of these for my friends and family for christmas, and I'd like to give them a complete working set with battery + charger. I'm also not confident that they'll be able to use alligator clamp rechargers... Depending on how this project goes, I might make an instructable with: 180 lumen on 1up rebel star LED, 700 mA buckpuck with dimmer, 6v 2300mAh battery pack (3+ hours), charger, same copper cap, aluminum heatsink for 280 motor with fins, bottom mount buckpuck/controls, knob controlled direction adjustment (hence the bottom mount buckpuck. Makes it easier to mount levers), velcro battery mount for packs Anyways, great instructable!

[jmengel]

Yes there is a problem running it off of 9.6V, at least with a 3-LED star. The LEDs are wired in series and each has a forward voltage drop of 3.2 to 3.5V each, for a total of 9.5V to 10.5V at 350mA and 700mA respectively. The buck puck constant current circuit requires an additional 2V voltage headroom to hold that forward drop at the rated current. So if you are running the star at 700mA your battery will need to be 10.5V +2V = 12.5V or greater. In practice, as the 12V battery voltage droops with load and depletion, the buck puck can no longer maintain the full 700mA output current and the brightness drops.

So, if you are going to use only a 1up Rebel star then you can use a 9.6V battery. A 2up will also be fine. However, you cannot run a 3up from 9.6V unless you find a 3-up wired in parallel.

Additionally, I don't know that you'd need the additional RC motor heat sink if you are only running a 1-up LED star. Good luck with your project.

-Jon

[stevers]

Thanks for the info, Jon! If I run a 1-up, the heat sink will mainly be for looks :).

I know everyone has been commenting and asking about battery options, and I do like the LiFePo (small 4cell is a big plus), but it's a bit pricey. Battery-space.com also said there's a hazard fee of +$20, so it would be a $80 battery + charger for 1350mAh. I may have to just drive up to richmond to pick the thing up. I wonder if they take walk-ins...

By the way, I have zero practical experience in electronics or soldering, but your instructable was such that I have confidence in working it.

Lastly, do you know of any clean 2 LED stars out there? I'm really keen on trying to get a standard 6v or 9.6v battery pack so I can make these en masse for my biking buddies. I like my friends, but not enough to buy them LiFePo batteries and chargers =).

Thanks!

[jmengel]

I do not know of any 2-up stars. One way would be to buy a 3-up and remove one of the LEDs. In terms of the battery, any >12V and <30V pack would also work. Some people use cordless drill packs which are rugged and cheaply available. You can use NiMH, NiCD, or Lead Acid. LiFePO is just the latest and one of the best technologies.

[retiredlawman]

Don't want to step on any toes, but I didn't see any link about DealExtreme.com. Excellent source for much, much cheaper LEDS, Luxeons, Stars, Crees, and drivers. Also good source for lights and bike [e-mail]. (Builder/user of extreme lights)

[josefski]

This site is awesome! Thanks for the link.

[jmengel]

Thanks for the link. I think I will order some of the drivers from this site for indoor applications, their bare driver circuits are crazy cheap. Comparing their LED prices, they do have some OK deals. They don't seem to sell a 3-LED rebel star, which is pretty much the ultimate for lumens per area. In an apples to apples comparison, it looks like a similar star from DealsExtreme is going to be $1-$2 cheaper (10-20%) which is not bad. Their low part numbers for quantity discount is also attractive.

[XilStorm]

more or less the same thing as this:
http://www.instructables.com/id/Ultimate-Night-Vision-Headlamp---500%2b-lumens-with-/?commentflag=1197172770613#CL3Y7GCF9T3NLK1

Try collaborating with the author next time for a single consolidated instructable. Because it's kinda annoying to hear the same thing twice. However, I think this has a better explanation. Cheers!

[jmengel]

Achtung! Don't feed the trolls.

[XilStorm]

Fair enough. Yours is a DIFFERENT take on the SAME concept. That's all I'm saying. Well, that and you actually explained it. Trolls: go argue somewhere else.

[tz1_1zt]

Instructables is about projects, not concepts. There is nothing wrong with suggesting an alternative or improved method. Why on earth would they collaborate when one is for a head mounted light and the other is for a bike light !?

The project that you linked does not deal with heat dissipation very well, this one seems much better. I'm going to replace my home made 12v halogen bike light with one of these. There are a few features in this instructable; http://www.instructables.com/id/Bright_Luxeon_LED_Bike_Light/ that I'll be using as well. The rc helicopter heat sinks are a great idea. One 3-diode module is enough for me though.
Great instructable, thanks.

[SimpleThoughts1303]

Is their a law of how bright of a light you can have on your bike so you don't blind people in cars?

[ajonesin]

what are you using as a power source?

[jmengel]

I think I discussed this in detail in a previous comment. Check that out. The short answer is a 12V Li-Fe-Po battery pack.

[retiredlawman]

Quad LEDS avail also.

[praveencivil]

it is very use for those use bicycle..but the problem is i cant get the exact parts you mentioned.give some aliter for me..

[jmengel]

Alternative parts? You can pretty much use any LED star and driver for this project as long as the back plane of the LED star is not electrically "hot". Not sure what the limitation is for you ordering the parts. If ledsupply.com doesn't ship to your locale, then try dealextreme.com. As mentioned by "retiredlawman" they have similar LEDs and drivers.

[anhoodouthingkur]

Could you possibly vent air through the light by putting holes in the copper housing?

[jmengel]

Waterproofing will be nullified, so this is not an option for me.

[Ledgehanger]

I have a 14.4 Volt battery pack from a (non-working) Roomba. The battery pack itself is in fine condition. Is there any reason I shouldn't use that battery pack to power this light? Thanks!

[jmengel]

The buck puck can handle voltages up to 24V for the AC model and 36V for the DC model and down to some small value above the total drop of the LED chain (2V for the DC version and 4V for the AC). So for example, if your LED chain drop is 10.3V at 700mA, then you will need a battery of at least 12.3V to maintain 700mA. In practice, the current (and thus light output) will drop as the battery voltage falls below this number. Your Roomba pack should work fine.

[grahamski1]

I am having trouble finding conductive epoxy. Where can I get either thermal or electrical conductive epoxy? Thanks.

[jmengel]

I bought mine locally at microcenter but you can order from their website. They carry both thermally and electrically conductive epoxy. I used electrically conductive since it has a higher metals content and thus reasoned the thermal conductivity would be better. MicroCenter sells both.

NewEgg sells thermally conductive glues in their fan and heatsink section.

You also might be able to use JB Weld which is available at your local auto or hardware store. It is a metal filled epoxy that is strong as well. No data on its thermal conductivity, but it is cheap and handy.

Good luck.

[ddw_az]

I will add two of these LED lights as backup lights to my Honda Rancher Quad, also one or 2 to the handle bars so that I can see where I am turning.

[cirano]

Love the spread pattern of the lamp (as opposed to a spot light). Very detailed Instructable. Thanks

[JamesRPatrick]

You made the Makezine Blog

[frenzy]

i bought a 4.5 watt high powered light from a cataloge, and this seems MUCH more powerful. thanks for doing it.

what did you use for a battery?

combine with my project and get awesome:
http://www.instructables.com/id/Putting_A_Car_Horn_On_Your_Bicycle/

[jmengel]

Nice horn. I've had a few opportunities where a horn could have been helpful. Well tuned front brakes seem to be the best solution usually. As I mentioned in some other reply, I have a number of different batteries that have been used to power my bike lights (and maybe horn in the future). The original is a 12V 7Ah battery that is heavy but fits a bottle cage nicely. The newest solution is a 12V Li-Po-Fe pack, which has only 1350mAh but is so light (only 4 cells) that it is worth the trade. I got them both (and others) at Batteryspace.com. Great site.

[XilStorm]

lol. if you're riding with other people, you could scare them off their bikes. Just don't do it in traffic =)

[mowdish]

Nice design. That o-ring mount is brilliant. I envision it solving several problems for the future. And my hats off to you for the Simpson reference.

[jmengel]

Thanks for the feedback. The o-ring mount is commonly used for cyclocomputers, I can't claim it as my idea at all.

[buzzardbeak]

Fantastic! That is exactly what I was hunting for! Which specific LED and puck did you use? I looked at the link and can't quite figure it which combination you used. Thanks!

[jmengel]

I used the Cool White, 270 Lumen 3 Up Endor star. I drove the LED array with a 3023-D-N-700mA Wired BuckPuck, non dimming.

[Yerboogieman]

Looks steampunk.

[WyoJustin]

Awesome project! Thanks.

[JonathanPeterson]

I don't know that a spot lens is really preferable. One of the big problems with led bike lights is that they don't have as much scatter as halogen bulbs, so you aren't as visible to drivers on side streets. If you're throwing that much light out there, drivers are going to know there is something out there - even if it might be a low flying plane.

[dchall8]

Very nice Instructable! Have you looked into aluminum heat sinks like those used to cool computer CPUs? Or there was another bike light Instructable posted about 2 days ago that used the finned aluminum heat sinks from a 280 R/C helicopter motor. Is your lens a flood type or a spot type. Bicyclists usually like a flood light. I wonder if you could use two O-rings to hold the lens in place. Size the rings to be slightly larger than the ID of the copper. Insert one O-ring, then the lens, and then the second O-ring to sandwich the lens between the rings. You can pick the O-rings out with a dental pick or other very sharp, curved object. I would think heat would be a concern for any lens mount. You didn't mention how you power the light. What do you use and how long does it last?

[jmengel]

I did look into heat sinks somewhat. I was not able to find anything that fit the bill. I definitely did not want a big square CPU sink on there, I have a lot of those sitting around and think the copper body itself is passable for now. However, looking at the heat sinks for R/C motors, they seem perfect. Thanks for pointing that out. I will look into getting one with the right diameter and attaching it with conductive epoxy. The lens is a flood, with a pretty wide spread, about 60 degrees I would estimate. I have not found many lens options for Luxeon Rebels yet, they are pretty new and accessory products are not up to speed yet. My bike runs a 12V system, with branches for the front head light and the rear xenon flasher. I have a lead acid battery that fits a water bottle cage I use on my mountain bike and a Fe-Po lithium pack on the commuter. The lead acid is a 7 Ah unit and was sized to run my previous 25W halogen system for 2.5-3 hours (at about 2A). With the LED headlight, the run time should be much longer but the battery capacity has degraded over the years and even with the 500mA draw of the LED the run time is only about 4 hours. Additionally, the buck puck has a cut-off voltage where the output current begins to drop as the battery voltage drops. With the new Fe-Po lithium pack (1350 mAh) the run time is estimated at over 2 hours although I have not run it to shut-off.

[dchall8]

Is that the power supply the police use on their bikes? Where do you get one? (probably at a bike shop, duh). Are they expensive? (again, duh!) I wonder how long you could run your light from a couple CR123 batteries (3 volts each)? Have you tried that light at only 3 watts? Seems like 250 lumens would be puh-LENTY for a hand held light. And running lower current should be significantly cooler on the hands. Hmmmm. You might be able to mount it in PVC fittings if it's cool enough. I'm just brainstorming here. Have you tried tinning the inside of the copper with silver solder to make it entirely reflective inside between the LEDs and the lens? This is such a great Instructable.

[jmengel]

When you say "power supply" do you mean the "buck puck" constant current driver? If so, the bill of materials step has a link to the website that sells these. I used the 700mA version, there is a 300mA version that will run the light at 250-300 lumens depending on the LED bin you shell out for. www.ledsupply.com If you are referring to the battery as the "power supply", I bought all of my batteries (and a few chargers) from www.batteryspace.com. They sell an amazing range of batteries. I have no idea what police have on their bikes. I ran my 25W halogen lights in PVC, the difference is that the LEDs lose efficiency and lifetime when run hot where the halogen runs better. The PVC got hot, but not enough to melt. Lithium (primary, non rechargeable) CR123 3V cells have a capacity in the range of 1400mA so 4 of these in series would run the light for about 2-2.5 hours.

[Scott_Tx]

Nice. If you need more heatsinking I'd improve the contact the light makes with the handle bar. Shape the bottom to make more contact, remove the tape and add some heatsink compound between the two.