The Smell of Molten Projects in the Morning
Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
Perhaps there’s something to redundancy after all:
The four light fixtures serve as both tail lights and brake lights. This was at an intersection, we were both stopped for the traffic signal, and all those LEDs should have been glowing brightly.
AFAICT, each light fixture has 20 LEDs with a third to a half either dead or dying.
I wonder if those are replacement fixtures, installed on the promise they’d last forever, when the original incandescent bulbs burned out …
LEDs are wonderful, in some applications, but they sure don’t live up to expectations
For what it’s worth, the situation seems a) largely confined to large trucks and busses, and b) has been getting better in the past few years. I suspect packaging issues were a problem, both for integrity and vibration resistance.
I’ve noticed very few failures in standard cars & trucks in my weekly market trips.
As a side note, the LED traffic signals seem to have improved over the 25+ years I’ve seen them in operation.
Must be something good in the air out your way, because around here LEDs have conspicuous failures.
Even new cars show a few dead LEDs in their clusters; the most recent example was a nice Caddy with a dark spot in one of its stylin’ slash taillights.
Contrary to what I used to think, it’s not the LED driver circuitry, because I see plenty of single dead LEDs.
I wonder if the taillight warranty is like an LCD monitor, where a dead pixel or two doesn’t count as a problem. :shrug:
Air quality might actually have something to do with it. I get considerably less rubber degradation in tires (those in the shade–UV still a killer) here than in Silicon Valley. Other possibilities could lie in the local (county and city) government’s aversion to using salt on the road. While state highways use brine, county and city roads use cinders and/or gravel at best for traction.
The brine use is less enthusiastic at the “lower” elevation roads (4200′) than for the mountain passes (5000’+).
Plastic packages and contaminant exclusion are not well acquainted. I think it’s worse for the tape type strips.
Often it is one circuit design for all colors. If there would be three white leds in series, the same pcb will be used with three red leds in series. Making it worse, they then put these chains in parallel and add one single resistor.
The Smell of Molten Projects in the Morning 
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