Cree P4 Quality Control

[moon lander]

i was just wondering if there is a way to test a batch of Cree P4s for quality before i install them. will every Cree P4 run at the same current given the same power supply?

also, is there much variation between them? ive bought a few from dx and i cant confirm that there is any variance but it seems like one of my P4s will only run at half the current given the same batteries as the others. im not super experienced with the multimeter so its possibly my error. is there a need to test them before installing them?

thanks in advance!

 

[Gnufsh]

Crees aren't binned by Vf, just by flux and tint. So, given a fixed Vf there is going to be a wide variation in current draw (especially because the I vs Vf for LEDs is nonlinear). That is why many people use constant current drivers instead of constant voltage regulators.

 

[moon lander]

Crees aren't binned by Vf, just by flux and tint. So, given a fixed Vf there is going to be a wide variation in current draw (especially because the I vs Vf for LEDs is nonlinear). That is why many people use constant current drivers instead of constant voltage regulators.

interesting. so the Cree P4 im using is only drawing 480ma at about 4 volts, so with a fully charged 18650 on direct drive, this led should survive where others would burn out. several of the other P4s i have draw 900ma at 4 volts. im really suprised at the amount of variation. anyone else experience this?

 

[AlecGold]

I think I've read several other similar stories about this!

 

[moon lander]

ill test the current on several tonight, as run off the same battery. ill try to confirm this and post back here.

 

[AlecGold]

cool, i'm intrested!