[Astronaut3315]

Adding more LEDs to the design allows them to be underdriven, increasing efficiency and longevity. The driver board and LEDs run cooler that way. Less heat equals less stress on electrolytic capacitors, a common failure point.

There’s only a few bulbs I’m aware of that follow this pattern. The Philips Dubai Lamp takes this to an extreme. A 60W equivalent uses only 3W. Other 60W eq. LEDs tend to be ~3x that. All that heat has to go somewhere.

I just picked up a 40W eq. bulb from IKEA that has double the normal amount of LED strands- they’re unusually long, too. It also uses about half the power of the LED bulb it replaced. I expect it to last quite a long time.

[ssl-3]

Someone thinks your comment is worthy of down voting, but you're absolutely correct.

Heat is a primary killer of many electronic things, including LED bulbs and their constituent parts.

And LEDs -- the diodes themselves -- do tend to become more efficient (in terms of lumens produced per Watt of input) when not pushed to their extreme operational limits.

And it is definitely possible to create a longer-lasting, more-efficient LED bulb.

It's absolutely trivial to do this, even: To start, just add more LEDs, reduce their individual RMS current, improve heat sinking and dissipation, and use better capacitors.

But it does cost more to do these things, and regular consumer products are all built down to a price.

[amluto]

> And LEDs -- the diodes themselves -- do tend to become more efficient (in terms of lumens produced per Watt of input) when not pushed to their extreme operational limits.

This isn’t some weird surprising tendency. The forward voltage (the amount of energy needed to shove each electron through the LED) increases with current, approximately according to the Shockley equation. The external quantum efficiency (photons out per electron in) is no more than 1, and tends to get lower at higher current [0]. The wavelength of the emitted photons is pretty much constant. So you get the best efficiency when the current, and hence voltage, is low.

Incandescent bulbs, in contrast, don’t have a meaningful quantum efficiency, and they produce a more useful spectrum as they get hotter.

[0] There’s a ton of detail here, for example https://www.degruyter.com/document/doi/10.1515/nanoph-2018-0...

[ssl-3]

Thanks.

Approachable explanations like this are a huge part of the reason I hang out here.

[shawnz]

Consider also the new Philips Ultra Definition series: https://www.youtube.com/watch?v=XeR2uPPCA2k

[Astronaut3315]

If only they were available in 3000k. I made an exception for the specific fixture the IKEA bulb ended up in, but our entire home is 3000k throughout.

[sbierwagen]

? https://www.usa.lighting.philips.com/consumer/p/ultraefficie...

[Astronaut3315]

These aren’t the same as the Ultra Definition series they mentioned, unfortunately. They lack the dim to warm feature that makes those desirable. RAB is the only manufacturer I’m aware of that makes 3000k dim to warm A19 bulbs for the US market.

The RAB bulbs have a weird stair step warm-then-cool when turning on and off. They also have a huge non-linearity when dimming. That makes the Philips version more desirable, but they’re 2700k.

[yjftsjthsd-h]

> It also uses about half the power of the LED bulb it replaced.

This may or may not be the only thing in play for that much of a difference, but my absolute favorite thing about LEDs is that their power consumption vs brightness is not 1:1, so taking an LED to 50% brightness will use <50% power. (So then doubling the number of LEDs means you will always get more brightness or less power or I suppose both if you split the difference.)

[Astronaut3315]

The old bulb was a Cree, rated at 460 lm, 3000k, 90+ CRI. It used 5.5W.

The IKEA bulb’s rated at 450 lm, 2700k, 90+ CRI. It uses 2.8W. Both are dimmable and I suspect the IKEA bulb has a higher R9 value.

[jchw]

I would love to know why this is apparently being downvoted, as far as I know it's true. A lot of cheap LED bulbs use few LEDs being grilled at relatively high current and definitely get hot enough to impact the lifespan of the LEDs. Am I missing something?

[Astronaut3315]

My initial reply was a bit rough around the edges. I've since edited it for clarity.

[jchw]

Ahhh I see. I know it's discouraged to discuss voting for good reason, but I was definitely perplexed. That makes a lot more sense.