what’s hot to a person is not hot to a piece of silicon or metal.
Yes, but my house was built about the time CFL’s were becoming popular, so it uses traditional incandescent fixtures. these were designed to take conical floodlights pointing straight down, in a recessed opening not much bigger than the maximum bulb diameter. There are CFL versions that are basically a spiral CFL inside a frosted outer glass cone. Some have lasted 4 years, a few died in 6 months.
I don’t think I want to put anything that gets excessively hot in these pots until I am sure the heat is not an issue for the fixture or the LED itself. Not sure if these are designed to mount face-down in a tightly enclosed space. When I last looked, these were $20 or $30 apiece. My house has over a dozen of these fixtures. CFL is fine for now.
A temperature rise of as little as 5C can half the lifetime of electronics, as mentioned in this capacitor datasheet; “The endurance of capacitors is reduced with internal heating produced by ripple current at the rate of halving the lifetime with every 5°C rise.” (this also applies to external heating from other sources; these particular capacitors are only guaranteed to last for 2,000-5,000 hours at 105C, so to meet a 50,000 hour spec the temperature has to be as low as 80C, which is well below the typical maximum of 125-175 for silicon semiconductors).
This also applies to LEDs, which lose a third of their brightness by the time their rated life passes, and is strongly dependent on temperature to a similar degree as above (thus, that is why a LED bulb might be rated at 50,000 hours but things like digital clocks run for many times longer with no noticeable degradation, even when comparing individual segments; at least, the 30 year old clock I have had since I was a kid doesn’t, and it was already rather old when I got it from a garage sale). Of course, other things like drive current also factor in, with lighting-type LEDs driven far harder per chip area.
oh I’m aware, but Magiver seemed to be approaching it as how hot LED bulb assemblies are by feel. Maybe I’m too trusting, but I tend to assume that with a quality LED bulb made by a recognizable brand, the heat sinking is suitable to get the rated life out of the diodes + electronics.
the other thing to keep in mind is that since so much of the LED bulb assembly is heat sink, they have a lot more thermal mass with which to transfer heat to your skin. a 60°C chunk of aluminum is going to feel hotter to the touch than a thin glass shell which might actually be significantly higher temperature.
But way less hot than halogens, which is what I’ve replaced. Under my kitchen cabinets right now I have a mixture of halogen 10W bulbs and LED 1.4W bulbs. (I’m replacing the halogens as they die.) The halogens give off loads of heat, the LEDs hardly any.
When I replaced all the halogens in cans in the ceiling I thought all the fins were decorative just to fill out the space in the can as the actual lighting area is much smaller, but apparently they are cooling fins. The LED floodlights outside lights have huge fins. They do a good job of lighting up an area, but as mentioned up thread, are a little intense of you look at them.
I am certainly looking forward to when LED distibuted arrays are available for lighting.
OK, this is a bit of a zombie, but I just went to Home Depot and bought a Cree 6w (40w equivalent) LED bulb. The cost of these has really come down over the last year, and they are now cheap enough that the playback time is around 3 years compared to a CFL (for 24/7 use, which this is).
I find that pretty impressive - CFLs were already pretty energy efficient, but this is 50% more efficient!