Innacurate LED Binning

Just wondering how inaccurate Lumileds binning process is. I received 2 UX1N LEDS sometime ago and used one right away and it was expected. The X1 color was HID Bluish and using 4x AA Nimh cells draws around 1.4amps. Last night I finally got together the other light using this same Bin LED. The color is way different like WO tint and using the same battery's draws 1.7amps! It's seems that this was a mistake or there binning system leaves alot to be desired.


Mac

Did you measure the Vf at the rated current? Other than that one point I don't think they specify the voltage at any other current (which is kind of what your measuring DD current is doing).

I don't know about your tint problem.

Greg

To be a little more clear. The voltage versus current plot for two LEDs of the same bin could look like two sloped lines that cross at 3.75V (say). One line is a bit steeper than the other. Now draw a horizontal line across the graph at 5.0V (the loaded voltage of your batteries, say). You can get a big difference in current if the two lines are fairly horizontal even though the two LEDs are from the same bin.

Greg

bins are ranges - maybe you got to extremes within the range?

greg_in_canada said:

Did you measure the Vf at the rated current? Other than that one point I don't think they specify the voltage at any other current (which is kind of what your measuring DD current is doing).

I don't know about your tint problem.

Greg

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No I didn't measure the VF at the rated current as I *thought* both LED's being the same BIN would have been close not 350 Milliamps different with the same battery's.


Mac

cmacclel said:

No I didn't measure the VF at the rated current as I *thought* both LED's being the same BIN would have been close not 350 Milliamps different with the same battery's.


Mac

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The seemingly small differences in Vf within a voltage bin can result in large differences in current in a direct drive setup. Thats just the nature of the slope of the LED voltage/current relationship. And as someone has already mentioned, a bin is a range, and tints of LEDs within the same bin, when compared with each other, can appear to be dramatically different.

cmacclel said:

Just wondering how inaccurate Lumileds binning process is. I received 2 UX1N LEDS sometime ago and used one right away and it was expected. The X1 color was HID Bluish and using 4x AA Nimh cells draws around 1.4amps. Last night I finally got together the other light using this same Bin LED. The color is way different like WO tint and using the same battery's draws 1.7amps! It's seems that this was a mistake or there binning system leaves alot to be desired.


Mac

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Just last night I had a WX1T turn green then blue or something like that. Of course you can figure what color it turned next


This mistake made me realize that the heatsinking has a lot to do with the color


I assume you are not using a star so be sure the emitters are getting good contact with the post.

Yeah, the fact that they are ranges is VERY important. I've bought four TW0Js that were physically attached and they ranged quite a bit in tint. I'm not really a big tint junkie and as long as it's not really deep into the violet range, I don't usually mind. Actually, I generally prefer the X0 bin and it seems to be one of the smaller bin ranges but the two best LEDs I've ever had color-wise were both W0s.

I've not personally seen a huge range in *X1* Luxes, but within the *V1* I've seen ones that I really like a lot (including in my personal 3D Magmod) and I've seen ones that are very unpretty!