| General > General Technical Chat |
| I thought LED lights were efficient? |
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| TimFox:
I never watch the videos. How many lm/W can be extracted from the arc? |
| BrokenYugo:
A quick google indicates something like 4 to 9 lumens/watt for carbon arc. |
| Zero999:
--- Quote from: james_s on April 09, 2022, 09:49:06 pm --- --- Quote from: cdev on April 09, 2022, 12:37:10 am ---How do they do in cold weather. When its cold, it seems some LED lamps struggle to stay lit. CFLS are even worse. I've never read about this. --- End quote --- LEDs love the cold, I've never heard of one having trouble in cold weather. Certainly none of mine have ever caused me problems, the coldest I've ever seen it get here since installing the LEDs was about 12F and they were perfectly fine in that. --- End quote --- If that's the coldest it's been in 10 years, that's pretty mild compared to most of North America and much of Europe. Presumably you live on the west or south coast. It did get down to -12°C back in December 2010 where I live in central England, which is very rare, where the normal coldest night is -6°C. I didn't have an LEDs outdoors back then, but my parent's had some CFLs outside and they carried on working, although I believe they were the bi-pin type with the internal starter and external magnetic ballast. I don't think it's the LEDs themselves which have a problem with the cold, but the electrolytic smoothing capacitor, which can increase in ESR at low temperatures. It would be interesting to hear someone's experience who lives in a colder climate. |
| wraper:
--- Quote from: Zero999 on May 27, 2022, 08:39:39 am ---I don't think it's the LEDs themselves which have a problem with the cold, but the electrolytic smoothing capacitor, which can increase in ESR at low temperatures. It would be interesting to hear someone's experience who lives in a colder climate. --- End quote --- ESR increases but not that much to break operation of something which is not broken by design and is not marginally operational at room temperature (unless cooled to extremely low temperatures). |
| Zero999:
--- Quote from: wraper on May 27, 2022, 09:10:41 am --- --- Quote from: Zero999 on May 27, 2022, 08:39:39 am ---I don't think it's the LEDs themselves which have a problem with the cold, but the electrolytic smoothing capacitor, which can increase in ESR at low temperatures. It would be interesting to hear someone's experience who lives in a colder climate. --- End quote --- ESR increases but not that much to break operation of something which is not broken by design and is not marginally operational at room temperature (unless cooled to extremely low temperatures). --- End quote --- It wouldn't surprise me if a good number of LED lamps are prone to malfunction, or even failure at very low temperatures. The ESR of an aluminum capacitor roughly doubles, every time the temperature is reduced by 15°C. If the person designing the circuit chooses a part specified at 25°C, the ESR will increase by an order of magnitude at -30°C. The capacitance also drops off a bit and lower temperatures, which doesn't help. https://www.avnet.com/wps/portal/abacus/resources/article/understanding-esr-in-electrolytic-capacitors/ https://www.researchgate.net/figure/ESR-versus-ambient-temperature-for-sound-capacitors-measured-at-66-kHz_fig1_29640251 https://www.dfrsolutions.com/hubfs/Resources/services/Uprating-of-Electrolytic-Capacitors.pdf https://www.rs-online.com/designspark/suffering-from-esr-fluctuations-due-to-temperature-maybe-its-time-to-polymerise |
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