With the arrival of spring, I am once again longing for a rip on the open road and a little wind in the face with the rap of a high strung 4 banger UJM hot rod under me. But, let’s apply a little context as it relates to this years 52/52 project. While the previous works pursued in 2010 were focused on off-the-cuff works, with the majority being task lights, this year I am not remaining within those narrower bounds. For 2015, I’m going to present application of LEDs and SSL technology wherever I find a place for it, in actual applications, including, but not limited to lighting applications. There is a simple reason for this. My interest and pursuit of solid-state lighting integration is not bound to architectural lighting, it also includes UV curing and artistic application and, in this case, recreational uses.
Over the last several years I have been on a quest to convert all of the incandescent lamps out of an ongoing WIP motorcycle project. It seemed simple enough, as there are many made in Asia LED products sold through motorcycle retailers. The problem is, when you dig into them, they are either complete junk, weak performers, or did not fit the design of the project in hand. Nowhere did this become a major challenge more than the headlight. Motorcycle headlights serve two purposes – to light the way at night, and to create a daylight presence that catches the attention of motorists who are blind to bikes (some of the more mentally challenged motorists in this world see what they expect to see – which are cars – they are literally blind to seeing bicycles, motorcycles, animals, etc… so run over, drive in front of, and crowd these invisible obstacles out of their path.)
Compounding the issue of effective forward lighting, motorcycles, especially older ones like the one I am working on (1979), have fairly wimpy electrical charging systems, so voltage delivered to headlights tends to sag, delivering less light and warmer CCT’s. It seemed a perfect fit for application of LEDs operated from a current control driver, as this could eliminate the output droop from voltage drop, as well as increase the CCT of the light output to optimize visual performance and presence on the road. Unfortunately. sifting through the myriad of garbage being sold as LED H4 lamp replacements took some time, and included evaluation of several alternatives, many deemed useless scams. I discovered that without some form of cooling system, the LED bulbs either were not delivering enough light, or were operating at such a high temperature, they were likely to fry themselves and fail in less time than the halogen lamp I sought to rid myself of. However, over the course of this winter, several new lamps came into the market that are looked promising. While not yet perfect, I found one that not only fit well, but delivered more light than the original halogen lamp. I was finally able to finish the LED conversion project this week, ending a two-year effort at last. The new system presents a load of 12W or 14W, replacing the 55/60W H4 Halogen lamp, while measured light output is increased by 15% (at full battery voltage, significantly more when the battery voltage is lower). The lamp includes an active heat sink and fan to keep it cool, which I found in bench testing worked surprisingly well. In fact, the thermal slug-to-heat sink is very similar to a design I have used in several product designs with similar optical demands. Not really wild about the fan, so will keep an eye on that, but its necessary to produce the output and longevity I was looking for.
In addition to forward , the headlamp integrates the turn signals. At the right and left side are amber LEDs embedded into the lamp reflector, which serve as turn signals and emergency flashers. At the center is the H4 LED conversion lamp, which incorporates a current driver, cooling fan, and controller circuiting that maintains full light output, even when battery/system voltage drops to as low as 9.8V. The tail-light includes red LEDs and a controller that and white LEDs with a clever resister/bypass circuiting that lights all of the LEDs at a lower intensity for standard tail-light function, then brighter when the brake light is active. The rear turn signals are a Frankenstein creation of mine that includes custom interior bits to integrate proper Amber LEDs into the bullet shaped housing originally designed for a small incandescent lamp – I was unable to find any off-market products that had the brightness I wanted.
The turn signal conversion to LEDs created an issue with the flasher system. Flashers in older vehicles are nothing more than a thermal cutoff switch that auto re-sets. When on, an internal leaf or coil heats up, breaking the circuit (off state), which then cools quickly and re-connects (on state). These are “tuned” to operate with a closed circuit, which an incandescent lamp provides. The load of the lamps in the circuit creates a resistance, which the flasher is tuned to, creating a flash rate based on how much voltage is present in the system based on how many incandescent lamps (acting like resistors) are in the circuit. This is why the flashers blink faster when a lamp is lost – increasing the voltage in the flasher “heater”, causing it to heat faster, thus, blink at a faster rate. Well… LEDs do not create a closed circuit for this process to work with. This requires either placing a resister into the system to create a closed circuit load similar to the original incandescent lamps (seems kind of silly), or replacing the flasher itself with some other modulating device that can blink without the closed circuit connection. Motorcycles present a few odd wiring flukes that complicate this, so the solution requires a little custom hacking. In my case, I was able to find a flasher kit from an on-line electronics kit outlet, that was then modified to work within the bikes wiring system. Problem solved.
In the end, the compelling reason for this entire conversion included several desired advantages. Incandescent lamps on vibrating motorcycles is a bad thing, LEDs don’t suffer this malady so no more constantly burned out bulb issues. Incandescent lamps present a load to relatively feeble motorcycle power and charging systems. The LED conversion reduced the load on the charging system and battery system from 94W to just 26W total, which allows the charging system to be used by the ignition system, at a more constant output voltage – while delivering brighter lights all around, and decreasing the time it takes to recharge the battery after starting. The LED headlamp conversion also increased the headlamp CCT from 3150K to 6500K, which is more visible during the day to numb-skull cage drivers, and increased visual performance while riding at night.
With this conversion, I am now down to just a few CFL and T8 lamps in the shop and garage, and just (2) halogen/filament lamps remaining in my home and work spaces. These will soon be gone as this years 52/52 projects puts them in the cross-hairs. Stay tuned….