As to the question of using the XPG LED instead of the XPG2 LED.
First, when we buy LEDs we get them by the reel or several reels at a time.
We still have over 750 XPG LEDs in stock. If someone wants to buy what
we have at the XPG2 price, we will gladly do that. ( No ).
Second, we have found here that the difference between the two in the
same bin at running temperature overlaps each other in output.
Third, Cree's own testing indicates a wide range of output over time at
the same drive currents and junction temperature.
XPG LED: @1000 mA drive, 73K hrs to 82K hrs
@1500 mA drive, 73K + hrs
XPG2 LED: @700 mA drive, 27K hrs to 51K hrs
@1000 mA drive, 24K hrs to 54K hrs
@1500 mA drive, 24K hrs to 36K hrs
The light output from the solid optics that we use shows a decrease
of 1 to 2 % less Lumems with the XPG2 over that of the XPG LED. There is
also a decrease in candelas in the optic used in the Eiger from 3.7 cd/lm
to 3.5 cd/lm as measured by Lideil. With the high output "X" units
that is an 80 candlepower loss as compared to the original "old" XPG LED.
The XPG2 requires an optic designed only for it to equal that of the XPG.
The Cree data sheet for the XPG states 493 Lumens at 4.9 watts maximum.
The Cree data sheet for the XPG2 states 488 Lumens at 4.8 watts maximum.
The XPG cost is less than the XPG2, yet Cree states that the XPG2 has 2.5
times the lumen cost advantage over that of the "old" XPG. ???
So after doing this research, until we get data that indicates that the
XPG2 is really better than the "old" XPG, we will more than likely still buy
the "old" XPG again.
Curt