LED Taillights, Diy

[Matt21lutz]

Originally Posted by kikkegek

Matt...lumen outputs are not that simple. look into this factsheet of Philips

http://www.philipslumileds.com/uploads/207/AB20-1-PDF

the output of an LED is determined by its application and one LED is not gonna output 10 lumens

also standard specifications for LEDS use the "DC Forward current" for comparison. Your LEDs will run fine on 15mA...but will get screamingly hot if run for a couple of minutes on 50mA. believe me I have tried. where these Lumileds (datasheet calls them Superflux) run only hand-warm at 50mA.

the peak value is only there to tell you what it can very briefly during "peak" its able to handle and it of no use for running lights or turn signal.

I looked at the color again and I now see that yours are 630nm..the ones I used are 624. so pretty close. that would make these leds more orange-red then red. But that is what you want for tail lights with a red lens.

I dont understand why your resistors would get that hot. I even used SMD resistors for my arrays to control the needed current and I believe I used one 1/4Watt resistors for dimming the LEDs and they do not even get hand warm. using the right wattage will make sure they are able to dissipate the load they need to handle.

All my thoughts and all the answers are in my build thread, but feel free to ask if you need.

for turn signals I just calculated the needed resistor with a online ledcalc and for the regular running lights I just did a test behind a lens and just swapped in resistors without soldering, holding them in series without soldering them in.

There is not set way to determine the difference between the two LED's because they used different way to measure the intensity. though a single led CAN produce 10 lumens IF the viewing angle is narrow, the way the led's I have now were tested at a smaller viewing angle. I actually have ran the led's at 50ma at 2.3v before, for 8 hours straight to test them, they actually didn't heat up at all still cool to the touch, mine never even get warm at all, not sure why yours are.

One problem with the datasheets that the Lumileds have is that they are only showing the PEAK and MAX rating not the average, granted the charts show you but there is not defined average or what they should be ran at, they do not say it within the text or tables. I've been all through all the datasheets before, researched and tested before, they were simply not as bright as the ones that I have now, i tested them both behind the lenses already, the Lumileds are not as bright. even if I am mistaken, i don't care, i do not want or need them to be any brighter than they are. Once again I want people to see me stopping NOT TO blind them.

Also it's fine to run them at higher current for turn signals/brakes, not for running lights though because it is only momentary and not staying at that current for more then a few seconds at a time and when u brake, none the less I'm running them at about 30ma right now. So that's fine.

As far as the way I want to reduce the power to the leds for running lights, I like the idea of using a voltage regulator because it's one less thing to worry about. otherwise i would still need to run a voltage regulate plus the resistor, resistor tend to burn out after excessive use anyways. I need to test it still, but I'm only dropping the voltage low enough that they will dim not low enough that they turn off.