Does high CRI always come at the price of efficiency? How much?

[bykfixer]

A couple years ago I really disliked some of the tints from Nichia. They seem to be reaching more natural looking products from what I can tell.

To my eyes a nice neutral leaning towards cool gives my brain the visual cues that seem more natural. But me, I'm not above using a rock to drive a nail if the need arises.

I like the charm of a 1930's 3D cell Burgess using a blown glass lens same as driving down the road with the top down on a 1950's coupe. But when it really comes down to it I'd prefer a 5700-6200 tinted flashlight and the comfy quiet ride of a newer Acura.

And I also consider a 2016 Nichia to be way more efficient than a 2005 (insert brand here). So sacrificing a few dozen lumens for a better tint makes me no nevermind anymore than less smog coming from my Honda Prelude that is being held back by emmision standards.

Sure, my Tana clad E2E could be brighter with a Cree, but the 3000k Nichia pleases my eyeballs more.

Basically if I need to ID something and fast, or to draw attention to an object, cooler works best for me. But for leisure I prefer the less efficient golden tints. So the practical side of me prefers something between a Malkoff neutral and a PK Design Lab cool.

 

[InvisibleFrodo]

Sure, my Tana clad E2E could be brighter with a Cree, but the 3000k Nichia pleases my eyeballs more.

This is exactly what I was talking about! Light for me has an immediate ability to "set the mood". Light can be pleasant, harsh, ugly, even strange.

"Pleases" being the operative word in my mind. Haha

 

[the.Mtn.Man]

Any loss in brightness/efficiency between warm high CRI and cool white is more theoretical than practical. You really won't notice any dramatic differences between the two in normal use.

 

[bykfixer]

Any loss in brightness/efficiency between warm high CRI and cool white is more theoretical than practical. You really won't notice any dramatic differences between the two in normal use.

Agreed 100%.

One night I used an M61WLL against an M61NLL in side by side comparisons. At a glance the slightly less bright W did not seem to light up objects at a distance as well... say 100 feet (30m). So I'd shine the N on say, a neighbors brick home staring at a crawl space vent. I could see the black handle that opens and closes it well enough.

During the first couple of seconds with the W it did not seem as bright. But after a few seconds my eyes could see the handle just as well as the N output.

I just prefer cool at times because my eyes don't need that period of time to adjust as they do using warmer tints. Say at times I'm in direct sunshine and shining a light into a dark place.... the cool 'appears' to light things better with less brightness required. At night things are a lot different than when a flashlight is in competion with the sun.

Open up a manhole in daylight for example. Extreme light vs extreme dark there. Using the same beam shape, a cool beam appears to light it better at first. If you allow your eyes to adapt a few seconds a warm or neutral beam is just as effective. Yet for me, I'm standing 8' from passing motorists so I don't want to stand around all waiting for my eyes to adapt. Shine a cool beam, see the issue, photo the issue and get the heck somewhere safer asap.

 

[John Rondo]

The efficiency drop comes from Blue and red phosphor used in high CRI LED.

There are two reasons for the efficiency drop:
High CRI LED need more broad specrum which will cause more mismatch between specrum and human eyes sensitive curve.
The other is deep blue and deep red phosphor used in high CRI LED is less efficient, and more energy is converted into heat.
The less efficiency for deep blue and red phosphor comes from reabsorption between different phosphor and low quantum efficiency themselves.
The second reason, i.e. heat causes your led more hot.:kiss:

 

[John Rondo]

The efficiency difference between Ra80 and Ra90 is about 10-15%

 

[HighlanderNorth]

Yes. High-cri LEDs will always be less efficient than standard cool-white ones. Cool-white LEDs have the thinnest phosphor layer and convert the blue light mostly to green and yellow. These are the wavelengths that the human eye is most sensitive to. Thus you get high lumens per watt (lumens is basically "light Watts" which incorporates the human eyes spectral sensitivity curve). To get high-cri you need a more balanced spectrum - i.e. more orange, more cyan and especially more red. The human eye is not very sensitive to red so you get lower lumens per watt even if you have the same watts of light ouputted after conversion in the phosphor. In addition to this the phosphor layer is usually thicker which further reduces efficiency.

That's a sensible explanation. It also reinforces my distaste for yellowish tints. I'm perfectly happy with neutral white tints. In fact, I have still never owned a true high CRI light. I always order whichever option that's not going to be blue or really yellow. If that also leads to better efficiency and lower heat, then all the better!

 

[Swedpat]

Tint is not the most important. But it's important for me if I have different options.
I have a few lights with Nichia 219 and not only the color rendition is better but also the eye-friendliness. Some manufacturers offer several tints including Nichia 219. And even if the output with Nichia is 1/3-1/2 lower than the cool white option I choose it any time without any doubt. The perceived brightness difference is not very big but the tint is awesome(I always choose neutral white when it's option if Nichia isn't, even if neutral sometimes is not close as good as Nichia).
It's something like the difference between a 2x50w and 2x100w stereo at similar price. But the 2x100w stereo has bad sound quality while the 2x50w has good sound quality. I don't need 2 seconds to choose the 2x50w model. Quality before power.
But that's me. The most important for everyone is to really enjoy the equipment and here different persons have different viewpoints of what's preferable.

 

[MeMeMe]

The efficiency drop comes from Blue and red phosphor used in high CRI LED.

There are two reasons for the efficiency drop:
High CRI LED need more broad specrum which will cause more mismatch between specrum and human eyes sensitive curve.
The other is deep blue and deep red phosphor used in high CRI LED is less efficient, and more energy is converted into heat.
The less efficiency for deep blue and red phosphor comes from reabsorption between different phosphor and low quantum efficiency themselves.
The second reason, i.e. heat causes your led more hot.:kiss:

Technically the quantum efficiency is pretty close for the deep phosphor and the regular phosphor, the issue is Stokes losses, Eff = QE * WavelengthPump/WavelengthPhosphor. QE doesn't change much, but the wavelength emitted does.