General > General Technical Chat
Explain to me the (de?)-evolution of LED lightbulb technology
Siwastaja:
--- Quote from: floobydust on March 25, 2021, 05:00:22 am ---But the driver board only gets cooled by convection inside the small chamber, which is pretty much useless obviously. Even if it (driver) dissipated 1W the temperature must be pushing well over 100°C.
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Quite frankly, the only Right Thing To Do is just to make the driver part efficient and not dissipate such power.
Modern white LEDs are some 40-50% efficient, we get that, you can't do much to improve it on the bulb level. You can go a bit higher by buying the most expensive state-of-the-art LED tech; or very crappy color rendition.
But there is no real reason why the driver circuit has to be some 70-80% efficient only. IMHO, seeing a charred hotspot on the driver board is inexcusable. 1W driver dissipation in a 5W bulb is a disaster, IMO, because there is no reason to be that crappy. Make it 90% efficient to see some real gain in power savings, and additionally the cooling problem is solved.
madires:
I think the big problem is that we are trying to replace incandescent bulbs with matching LED bulbs to keep the old lamp fixtures, The old bulb design is great for incandescent light, but not for LEDs. We should design new standard LED lights and fixtures to get the most out of LEDs. For example, I have several meters of 12V LED strips on aluminum U profiles. They stay cool and run great for many years.
amyk:
--- Quote from: floobydust on March 25, 2021, 05:00:22 am ---IC is BP9916C with CL set to 235mA (2.55R) and ILED 118mA, IC rated max is ILED 200mA.
"The thermal regulation temperature is set to 140°C internally." :scared:
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That's a switching buck converter, not a linear regulator... so it should be more efficient? :-\
TimNJ:
--- Quote from: floobydust on March 25, 2021, 01:15:40 am ---Philips LED bulbs 800lm 2700K 8.5W I put a dozen into service indoors and outdoors for night lighting, so ~8-10hrs/day in various fixtures and outdoors -35°C to +30°C, indoors +22°C.
They lasted about 1-1/2 year. On some the LED's have the "black dot of death" as BigClive calls it, the string went open circuit. But really, the power supply is a joke, it's baked phenolic with roast electrolytic. I had greater expectations for USD $4 each, so I'm calling them junk after all are dead now.
I bought a massive PAR38 Philips flood light bulb and laughed it back to the store, all it has is a small COB spot like their MR16 bulbs, it's all empty space and glass lol.
(did break the bridge rectifier taking it apart)
edit: compare the thermal conductivity of many plastics and they are basically an insulator. Patents prevent plastic heatsink fins from being used.
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Lmao come on, paper/phenolic board running at ~140C. :-DD
james_s:
--- Quote from: madires on March 25, 2021, 11:29:41 am ---I think the big problem is that we are trying to replace incandescent bulbs with matching LED bulbs to keep the old lamp fixtures, The old bulb design is great for incandescent light, but not for LEDs. We should design new standard LED lights and fixtures to get the most out of LEDs. For example, I have several meters of 12V LED strips on aluminum U profiles. They stay cool and run great for many years.
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They are doing exactly that, but there are billions of existing lamps and light fixtures out there, surely you can't expect everyone to replace all of their light fixtures? There is a lot of vintage/historical/period correct fixtures out there too. LED lighting would take decades longer to catch on if not for readily available retrofit bulbs.
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