Introduction: Twin High-Power LED Motorcycle Headlights
This guide shows you one way to make a pair of high powered LED headlights for your chopper, hog, crotch-rocket, cruiser, scoot, or just plain motorcycle. The design uses readily available copper fittings for the housing and some bronze threaded rod for the mounting. Each motorcycle install may be different than that depicted here but the general idea is applicable. Similar techniques are detailed in some of my other instructables linked below.
Step 1: Materials
The bill of materials for this build is :
1x: 12" of 5/16"-18 threaded bronze rod ($13.59)
2x: 1-1/4" standard copper coupling w/o dimple stop ($3.48)
4x: 1-1/4" standard copper cap ($2.19)
1x: 1-1/4" heavy duty Type K copper pipe 24" ($25.31)
2x: Neutral-white Cree XM-L star ($11.14 Cree Part# XMLAWT-00-0000-0000T50E4)
2x: Carclo 26.5 eliptical lens ($1.59)
2x: Carclo 26.5mm lens holder ($1.59)
1x: BuckBlock 2100mA driver ($19.99)
4x: Bronze 5/16"-18 machine nuts ($8.40 for 25)
1x: Cable gland with strain relief ($2.64)
Misc consumable items:
Lead-free solder for copper pipe (~$18.00 for 1 pound of solder)
From any hardware store
Conductive epoxy for mounting LEDs (~$35 for a 14g kit)
Regular epoxy for sealing, can use clear or filled (JB Weld e.g.)
From any hardware store
6 feet of 2 conductor stranded wire of at least 22 gauge
Silicone RTV for sealing lens to body
From any hardware store
Drill bits (1/2" and 7/64")
Common sense: Build safely, saws can cut you and torches can burn you.
Step 2: Cut and Prep Parts
The copper housings for these motorcycle headlights are going to be built nearly the same as the bicycle lights I detailed previously . The difference is that the housing for the motorcycle lights will be made with 1-1/4" fittings rather than 3/4" fittings. Also, the coupling is used full length to give the housing enough room to hold the BuckBlock and the pipe cap to hold the LED is cut taller and includes an internal section of 1-1/4" pipe to increase the thermal mass and make a better fit for the 26.5mm lens and holder. Also, the mounting style is different and uses a threaded rod rather than a bent wire cleat.
Holes for the wires to the LEDs also need to be drilled at 7/64" or so, holes for the threaded rods need to be drilled at 5/16" or so, holes for the wire between the headlights need to be drilled at 7/64" or so, and a hole in the end cap of the headlight that will house the BuckBlock needs to be drilled for cable gland at 1/2" or so. See pictures for more clarification.
The threaded rod is bent to allow soldering to the inside of the housing and to give the lights the correct aim when installed on the bike. You'll need to take some measurements of the bike and come up with the proper angle. Depending on the bike, you may opt for a different mounting scheme altogether. We considered using clamps around the fork tubes but eventually stuck with the stock headlight mounting holes. Bending the threaded rod will require the use of a vise to hold the rod while you carefully bend to the appropriate angle. Once bent, cut to length and dress any threads damaged during bending and cutting. To help the bronze rod stick to the solder, grind the threads that will touch the housing flat to clean any patina and to increase surface area. You will have to file out the hole in the copper housing to allow the threaded rod to sit properly as well.
Step 3: Solder It All Together
Prior to soldering, clean all the copper pieces with emery cloth (320 grit is good) to brighten them up, and then brush on a solder flux on areas that need to be soldered. Assemble all the pieces and clamp them in a vise to hold while heating. Position the housing so that the threaded rod is held in place by gravity and add an extra weight (such as a spare pipe cap) on the protruding threaded rod to help hold it in position. You need to solder all the joints at once, which can be tricky. If you are careful you can solder some of the joints first and then keep the assembly cool enough while adding other parts that you don't melt the existing joints. However, it is easiest to just solder it all at the same time. Fire up the torch (wear eye protection!) and heat the assembly until the solder melts on the housing and wicks into the fluxed joints. Oh, sandals are a bad idea as well since with all the heat and solder being applied you are likely to have hot melted metal splashing around.
Step 4: Wire and Glue in LED and Lenses
Next you'll need to run wires between the headlight pods (remember we want the LEDs in series) and wire them appropriately. Solder the wires to the LEDs prior to gluing them into the heat sink housings since with all that copper getting the solder to melt will be a real challenge. For wiring in series, you'll want the LED+ wire from the BuckBlock going to the "+" pad on one of the LEDs, and then a wire from that LED's "-" pad going to the "+" pad on the second LED and then finally a wire going from the last LED's "-" pad to the LED- wire on the BuckBlock. Since we're not using the DIM wires on the BuckBlock you can clip those and tape/glue over the wire so it can't short to the housing. Use shrink wrap on all wire splices so that they can't short together or to the metal housing.
Prior to continuing, it is a good idea to fire up the LEDs before committing to gluing things down. Hook up a 12V source to the BuckBlock, observing proper polarity. Only light the LEDs for a few seconds as they can get hot and damaged quickly without a heat sink.
Once the LEDs are wired and tested (be sure to thread the wires through the various holes in the housings before soldering) mix up some electrically or thermally conductive epoxy and glue the LEDs into the housings. I used the lens holders and a rubber band to apply consistent pressure and the keep the LEDs centered while the epoxy cured. If you are using an elliptical or otherwise non-symmetric lens then you'll need to be careful how you clock the LED in the housing since the lens holder only holds the lens one way. In the case of the elliptical lens, the lines on the front of the lens need to be perpendicular to the ground when mounted on the bike so I made sure that they were rotated correctly prior to the glue curing.
With the LEDs glued down, test for electrical connectivity from the LED pads to the housing. When using and electrical epoxy it can be easy to get extra glue to flow up onto the wires or pads. We don't want the housings to be part of the circuit so if any shorts have happened scrape the extra glue away until it is an open circuit. Test the LEDs again to make sure everything is working. You can run the LEDs longer now that they are properly heat sinked.
Next, glue the lens holder to the LED and seal the holes in the housing for the LED wires. I used a clear epoxy that I spread around the interior of the front end cap to seal the holes and provide glue for the legs of the lens holder. Be sure that you don't get glue on the dome of the LED and in fact keep the glue away from the LED as much as possible. Again use a rubber band or similar to hold the lenses in place while the epoxy cures. Once the epoxy is cured (best to wait overnight) you can snap in the lenses.
Step 5: Finishing Touches
Once the lens holders and lenses are installed, you can seal around the lenses using any RTV silicone or similar. I used a black liquid gasket RTV from an auto parts store that I had laying around. That finishes up the business up front, now for the party in the rear.
The final touches needed to seal up the light are to fit the BuckBlock into the appropriate housing (the left one in my case), epoxy the inter-housing wires, install the cable gland, install the external power wiring, and then glue on the end caps.
I applied a big dollop of epoxy inside each housing at the strain relief knot to hold the knot in place and to prevent leaks. The hole you drilled from the wires between the housings is hopefully really snug and on the bottom of the housing so leaks should be unlikely.
The cable gland includes an integral o-ring for sealing to the pipe cap but adding a squirt of RTV when installing is extra insurance.
Fitting the BuckBlock should be easy if you arranged things along the way and keep extra wire to a minimum. Using shrink wrap or electrical tape on your wire splices is also a must.
Pack all the wires into the housings and do one last operational test to make sure there are no troubles prior to sealing up the housing for good.
Lastly, apply epoxy to the end caps and slide them onto the housings. This will permanently seal the housing. If you prefer you can try using a plumbers putty or non-hardening PTFE paste that is viscous enough to keep the caps on but will not permanently bond the caps on. That way you can open things up in case something breaks down the way. Another option would be to melt wax/paraffin to keep the cap on, since these lights will not get hot enough to melt the wax when in use. Summer sun in AZ is another story.
Step 6: Testing
If you have access, testing of light output can be performed in an integrating sphere. I happen to have built an integrating sphere a while back and it provides a nice and repeatable method for evaluating light output. I don't have a calibrated source, but have been using a standard 120V 50W halogen MR16 bulb as the standard source. The MR16 puts out 8100 Lux on my meter while the motorcycle headlights detailed above put out 12100 Lux each. Based on published numbers for halogen bulb efficiency this is approximately 700 lumens from each of the motorcycle headlights. Not bad, not bad at all.
Step 7: Mounting on Motorcycle
Finally, go ahead and mount the light on your ride. You can paint the copper to match if you like or just let the copper age. Do some road testing to see if the lights are aimed to your satisfaction, you want to be able to see far enough up the road without putting too much light in the eyes of oncoming drivers. The elliptical lenses used in these lights has a narrow throw vertically but wide horizontally. If the lights need to be adjusted you can carefully bend the threaded rod (difficult) or shim with washers or similar (easier).
Step 8: Beam Shots
Finally had some time to take beam shots. I did not have a tripod handy so the crispness is a little lacking but the results come across. For comparison I also took some pics of the headlight beam from a stock CB550 with incandescent bulb on HIGH beams. The photos show that the LED has a much broader beam and a lot more light in general. The throw is pretty similar between the two with the incandescent is much more focused and directed. From a rider point of view, the LED is a big improvement over the anemic stock light. Comparison photos are taken with the same camera settings.