garage LED lighting project

[Brian_H]

Hi David.

I want to get this project done soon... I am nearing the completion of the modeling process so hopefully it won't be long before I start machining it.

As for learning things, this project has taught me a bit more about the heatsinking requirements of fixed led lighting, specifically how to determine the led Tj temperature, and about various diffuser materials. I also looked into existing led lighting products to see if it would be considerably cheaper to do it myself. It is, and DIY led lighting is currently the bleeding edge of the technology.

I have some basic knowledge to build upon, as I have been pretty much obsessed with flashlights and leds since about 2011, though I haven't built much... except for a spotlight which features a 600 watt 28v airplane landing bulb. It's pretty good for walking the dog and getting the mail and stuff.

30% seems like a lot of light to lose. I wonder if there is a more efficient alternative...

There are some diffuser materials that have manufacturer claims of higher efficiency. "Makrolon Lumen XT" is one, which is available in several different ratios of diffusion to transmission. There is also "plexiglas diffuse," which claims "good diffusion" and 88-92% transmission on most types, and one which has 60% transmission and "very high diffusion." Then there is "Diakon Frost," which is claimed to achieve nearly 100% diffusion at 80% light transmission or so. I will undoubtedly get ahold of these plastics in the future and test them out, but in the mean time I went with a readily available diffuser profile from "Klus," specifically the square "GIP" profile. Somewhere I saw that it is 70% transmissive, but I don't know how good the diffusion is compared to the aforementioned materials. I would rate it as having moderate diffusion; hopefully it keeps the glare down.

Your average metal reflector has substantial losses as well. A quality rhodium coated reflector will be between 70% and 80% reflective, though "protected aluminum" coatings can be around 90% reflective but are not as durable or as stable over time as rhodium. Silver coatings are the most reflective but are not stable in air and tarnish immediately. Then there will be slight losses through the glass lens, between 1% and 6% or so depending on the glass and whether or not it has anti reflective coating applied.