TK's Emisar D4 review

[tocirahl]

@leestrong

Could anyone comment on the maximum steady state lumen output of 219C and XP-G2 under temperature regulation?

I never had a high CRI light before so I like to try the 219C, but if that means reducing the steady state brightness by half, then maybe XP-G2 has higher practical value.

So hard to decide.

Take a look here:

Nichia 219C, testing a 5000K 83CRI emitter, comparing with a XP-G2 S4 2B and other leds

[image] The Nichia 219C is the newest upgrade in the 219 series. The Nichia 219 leds have become famous for their 90+ CRI variants, giving better colour reproduction than any Cree or other led, but in the performance section they were way behind Cree at start. But since back then the 219 has come a long way: the 219B performed way better than the 219A, and this test shows another huge leap with the 219C. The 90+ CRI versions of the 219C are not on the market yet, but I was able to purchase th…

At the same current, the 219C R8000 is slightly more efficient an XP-G2 S4 in terms of lumens / watt.

However, because of the much lower forward voltage, the 219C is going to pull a lot more current from the FET, which reduces the efficiency since lower forward voltage = higher current = lower efficiency.

If we put in some numbers: let’s say:

• the optics of the system are ~80% efficient

• the 219C version puts out 3800 OTF lumens = 950 OTF lumens / LED = 1190 LED lumens / LED

• the XP-G2 version puts out 3300 OTF lumens = 825 OTF lumens / LED = 1030 LED lumens / LED

Running that through the spreadsheet, we get:

• 219C runs at roughly 4.92 A, 3.425 V = 16.85W ==> 56.4 OTF lumens / W

• XP-G2 runs at roughly 3.11A, 3.755V = 11.67W ==> 70.7 OTF lumens / W

Thus the XP-G2 version should be roughly 25% more efficient per watt than the 219C version. That is to say, at some “steady state” wattage, the XP-G2 version will put out about 25% more lumens than the 219C, which would appear roughly 12% brighter.