I have an idea how to solve one of the problem of beginning modders.
We know that dealing with lack of voltage binning is a big minor side of Cree-enthusiasm. The problem is more difficult becouse I cannot find any precise information about Vf of the newer bins. "Higher than P4" - This not satisfy me and many of us. So I have a kind request and clever idea as well. Everyone who own Cree XR-E Q5 and especially R2 bins and who have capacity of measuring Vf at 1A accurately, please do follow:
Measure Vf of the cold LED, when it's heatsinked and when LED current is constant and about 1000mA (there can be a few percent error of course)
Type your results into the column. One column is the Q5, another - R2 bin.
We can also extend it to the R3 and more in the future.
If you have this information, please write the date of production/purchase next to it!
Q5#1 3,56V (11.12.2007)
Q5#2 3,58V *
Q5#3 3,60V *
R2#1 didn't bought so far
Thanks in advance!