Salvaged this Osram S2WP from a Nightwatch NI40, which had some issues. Thanks to Neal for sending it in for review, but other than the nice beefy host, the driver acted quite erratic and I never wanted to touch it.
The emitter is interesting. It’s a quad die LED which can was configured for parallel 4x 3V operation on the Nightwatch MCPCB. However, the forward voltage is very low, under 3V at most operating currents, so for optimal performance it needs preferably a buck driver for use with Li-Ion. A linear driver would waste a lot of power, since the voltage difference is large. Series config at 12V would be best, but at least this MCPCB didn’t seem to offer that possibility.
I don’t think this emitter fits on any ubiquitous solder pads as it’s smaller than an XHP70 but larger than an XHP50. This is more of a curiosity without many flashlights applications that I could think of.
Test was done on an Al heatsink. MCPCB was put on top of a graphite thermal pad and clamped securely down with two screws. Tests were done in an integrating sphere.
A single emitter is rated up to 5 amps of current at 25°C so four in parallel could theoretically go up to 20A and still be in spec. My PSU on only does 10A and since 4S config wasn’t doable, there is still lots more headroom above what I was able to test.
According to my results and the datasheet, this sample is flux bin SA, which should do 1800-2240 lumens when driven at 1400mA per emitter (5600mA total). This LED did 1830 lumens at 5600mA with an efficacy of 111 lumens per watt.
Voltage: 3V (four dies in parallel)
CRI: not specified (this usually means CRI Ra 70 at most)
Tint: 0.321x 0.327y typical on CIE1931 which equals 6073K with a duv value of –0.0020 (although can go anywhere between 5650K and 7200K with a duv spread of –0,0126 to 0.0088 as per chromaticity group BQ)
Flux bin: SA (1800-2240 lumens at 1400mA per emitter, 25°C)
Emitter size: 5.75 x 6.38 mm
Doesn’t look too good. Huge tint bin with probably atrocious CRI. Not for color critical applications
Output and forward voltage
Table with all the data at various currents
Measured integrated in a 50cm sphere, the tint on my sample lies below BBL at all times. CCT ranges from 5880K to 6400K. Efficacy is still fine even at 10 amps.
CRI at the rated 4x1400mA=5600mA current.
CRI at various currents
I didn’t measure it, but after trying the S2WP in the NI40, as is typical for a domeless emitter, the tint shift within the beam angle is very small. This will probably play nice with a wide range of optics and reflectors. Works fine as a bare emitter too. Other than being cool white and low CRI that is. I don’t really know who would want to use it.
edit: fixed a typo in the lumen calculations, which skewed the results (output is actually 6.4% lower than previously shown)
Added 8.12.2019 Data for a single emitter up to the maximum rated current of 5A