Correlation between Vf and lumens?

Hi all, I've noticed quite a range in the brightness of finished lights I'm building. I'm using MCE and XML driven at 2.8A with a linear driver and 1x18650. The spread of the MCE flux bin is 60 lumens and the XML is 30 lumens.

In the quest for better consistency I was hoping to test all of the LEDs I buy on the bench to eliminate any particularly low performers. Can I use Vf as an indicator of expected (relative) output?

Since the driver is CC, a LED with higher Vf should actually consume more watts (meaning brighter?)...but a lower Vf is more efficient and will allow the light to run in regulation for more of the battery life...is that correct?

If this doesn't make sense, I'm just trying to bench test my LEDs to predict which ones will be higher/lower performers. Although lumens and run time are two different performance characteristics and "seems" like they might be mutually exclusive...which sort of makes sense. Is there another way to approach?

Thanks!

No. LED brightness is based on the fact that some proportion of electrons become emitted photons. Structure of the LED determines brightness bin, then current determines output, moderated by heat.

So is there any useful information to be gained through binning by Vf?

archer6817j said:

So is there any useful information to be gained through binning by Vf?

Click to expand...

Yes. It can mean your LED is more efficient. It is also helpful to know for certain battery/driver combos where a high Vf will prevent the full intended current being reached.

Old thread but just to clarify, the lower Vf led puts out the exact same lumens as the higher Vf led, but the higher Vf led consumes more watts? (We are assuming a constant current driver and LEDs from the same bin).

Watt = Volt * Ampere = Joule/second

So same amps, more volts = higher "Watts" = Power.