which white led has the best efficiency?

i dont care about tint all i want is lumens per watt

Cool white outputs more lumens than neutral white, which outputs more lumens than warm white.

how about cree 6500 k vs sst 6500K which is better for lumens per watt

I don't know individual emitters very well, but Cree is generally quite efficient.

Very green tinted emitters around 5200-5700k will be the most efficient. Large die, domed, low CRI. Cree XHP70.2 OR 70.3 is probably the most efficient in a 7070 or smaller footprint.

I agree with Jared. The XHP 70.2 is just so efficient with the large dome and abundant phosphor. For ultra low power Leds, there might be something more efficient but I doubt it. The XHP 70.2 has over 200 lm/W when driven under 1A.

Overall, you still need to qualify it with a current range. The XHP 70.2 will not be the most efficient over 20A because the multidie Leds will beat it.

That's interesting about the XHP 70.2

I have one flashlight with that emitter, and it's my favorite flashlight and emitter.

There is a tint shift with the XHP 70.2 that some people don't like, but it doesn't bother me.

Another vote for the XHP70.2. My Thrunite T2 with a single XHP70.2 can run for hours on it's high setting. A ton of light and some serious runtime out of that diode.

Samsung and Everlight reach 230 lm/W with their mid power LEDs driven at really low currents. This is the best that I’ve seen. And I think it actually is with CRI80.

Also, depending on what application you are going after, mid-power emitters are a really good option. 200+ lm/W is available in abundance for very little money. Definitely where the value is at for diffuse lighting apps.

Well that was easily the best summary I’ve ever read. Thanks Quad :beer:

yes, we agree.
thanks Quadrupel.