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ck2

We talked about this a month or two ago here.

The amazing part of this bulb is not it's watts or it's cost.

It's that a manufacturer finally put it's warranty where it's mouth is.

With a 10 year warranty I will actually buy it compared to the Phillips.

BTW I've yet to have a cheap chinese led 110v bulb last more than 3 years.

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We talked about it here: https://news.ycombinator.com/item?id=5329732

And the biggest problem with this bulb is the CRI of 80. That's much worse than CFL's which are typically around 90.

Is that really the typical CFL number? I ask because I've got one of the new Cree bulbs and I find the quality of light really a lot better than that of the (admittedly cheap) CFLs I've bought at Costco.

So I guess I'm struggling with the significance of CRI.

It depends on which CFL you buy of course. But 90 CRI CFLs are easy to find.

In general "warmer" CFLs have a better CRI.

You can trade off energy efficiency for CRI. This is true for LEDs as well. So if you don't need great color then go for a lower CRI since you'll save energy on the light output.

But because of that, when comparing energy efficiency of LEDs vs CFLs you MUST use a comparable CRI, otherwise it's not a fair comparison.

But I'll save you time: There are no commercially available LEDs that beat CFLs in energy efficiency for the equivalent CRI.

I've found the exact opposite. I've found that there are many more "cooler" (~5600K color) CFLs with a high CRI than warmer (~2700K color) CFLs with a high CRI. The cooler 5600K lights are daylight balanced and used a lot with digital filmmaking and as indoor grow lights, whereas the warmer lights are used in home light fixtures to approximate the color temps of incandescents.

Thanks. That's a good way to sum things up.

As someone who is enthusiastic about LEDs from a distance (I'm not about to run out and replace all my lights at once) I'm comfortable with the idea that LEDs are still a couple of generations away from replacing existing technology in a satisfactory way. But damn, those generations sure are happening fast.

I became aware of Cree because of flashlight LEDs and what they accomplished in that space over the course of a year or so was pretty amazing. At present I can still take out my little AAA light with the newest Cree LED and say "check this out" and surprise people with its brightness. The early LED flashlights were largely junk, but in contrast, this is a great use of the technology.

Even the top-of-the-line CREE bulbs are only suitable for people who are color blind or habitually not paying attention. I once did an ill-considered change from halogen to LED bulbs in my kitchen, and having done so could no longer see the colors on my dishware. That was ridiculous. I went back to the halogens. My house is in a year-round heating climate anyway so I don't really worry about the waste heat from them.

I wonder if you've actually used one of the newest Cree bulbs? I'm not color blind and I found the color of one of their 2700k bulbs to be better than the CFLs I use in a few places. Come to think of it, they're a fair bit better than the g7power LEDs as well.

This is why I'm wondering if the CRI is really a magical "light goodness" benchmark number or what. Some people certainly seem to be treating it that way.

They were the best ones I could get my hands on. I believe their advertised CRI is 90. If you look at the spectrum though, they are still quite peaky/notchy. Halogens are very close to sunlight. Halogens with clear bulbs have CRI 100 by definition.

Yes, the latest LEDs are far superior to CFL. And oatmeal tastes better than dog shit.

Another thing to consider is that radiation outside of the visible light spectrum may have positive effects. For instance, halogens radiate a lot of infrared radiation, which is used in various therapies and is a big part of why being out in the sun feels so good.

cri doesnt mean too much absolutely, but it's the metric the standards associations chose to compare lights. after working with medical lighting for a while I've found myself paying more attention to the combination of cri and cct and/or cri and luminous flux. what people need to realize is that lots of other factors come into play such as ambient color mismatch and bleeding of adjacent colors. in some conditions even high cri lights don't appear to show color very well.

Chandeliers with prismatic glass are another problem area for LED lighting. My home has two such fixtures, previously populated with nine 40-Watt incandescent lamps each.

That's a lot of power dissipation (360 Watts), particularly since one of the fixtures was on up to 12 hours per day (4KW-h almost daily for that).

So I replaced all nine bulbs with TCP LDCT3WH30KCC 3-Watt (15 W incandescent luminance equivalent) 3000-K 80-CRI bulbs. 27 Watts, down from 360.

Excellent energy savings, excellent dimmability (better than the incandescents), but all those beautiful violet, green, blue, gold and other various facets of color from the prismatic glass were just gone -- collapsed down to a cold white; as if the glass weren't prismatic anymore.

I do not understand why I don't see at least some narrow-band stripes of some few individual colors.

So I put back just two 40-watt incandescent bulbs. That was enough to bring back a nice refractive color spread from the prismatic glass. The dissipation is up to 91 Watts from 27 Watts, but it's beautiful again.

Energy problem resolved satisfaction (75% reduction), while keeping the aesthetics alive too.

That's pretty interesting. I bet it has something to do with the polarization of light. If so a bulb like the Cree (with its glass casing) might help, although it might look goofy in that particular fixture.

I doubt it's the polarization. More likely it's that the incandescents are point, or line sources (non-frosted bulbs), but the LED's are much wider - so you are still getting colors, but since you have multiple color in multiple spots they overlap, mix, and are back to being white again.

Try to get LEDs that have no diffuser lens in front, since the LED itself is a point source.

"That's much worse than CFL's which are typically around 90."

How did you come up with that typical number? Typically, CFLs meet the minimum energy star requirement which is 82.

If you don't believe me, browse through GE's catalog for a while...

http://genet.gelighting.com/LightProducts/Dispatcher?REQUEST...

Is it correct to assume that CRI stands for color rendering index? New term to me. https://en.wikipedia.org/wiki/Color_rendering_index

Yes. And it is the measure that for example interior designers are passionate about. The problem with LEDs has been their poor CRI, but Philips has been able to produce LEDs with CRI above 90.

Until your LED bulb starts making a strange noise and you discover these things actually have a cooling fan inside of them. This thing WILL fail if kept running for a long time.

https://www.youtube.com/watch?v=5avJVvrFedc

MR16s (the type of bulb in the parent's video) are tough because of their size and limited surface area relative to their lumen output. Most retrofit lamps such as the A19 (the form-factor that most people think of when they think of a light bulb) have 100% passive thermal management. That said, there are a few really good fully-passive, high-output MR16s on the market.

I believe switching capacitors in the power supply are what limit the lifetime of most LED bulbs - electrolytic caps being one of the worst offenders. Good thermal management helps mitigate these problems, but a lot of failures are chemical in nature - caused by the degradation of the capacitor's electrolyte. This is why we've all seen the capacitor choice in motherboards and PSUs used as a marketing item.

Full disclosure: I used to work for a well-known LED lighting company, but please take the above with a grain of salt as I am not an electrical engineer. [Edit: And of course, these views I've expressed are my own and not representative of my past employer.]

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