I got in my SkyRay Kung M4 4xXML U2 light in today. Took a whole week to get it from China! Tossed it into the Sphere ’o Many Mysteries.
4.5 amp tailcap current on high (with 4.0V in from a bench power supply giving 3.7V at the driver, 3.8V in gives 5.6A, 3.9V in gives 6.5A)
Measurements with 4 fresh 2900 mAh Panasonic cells:
High: 1920 lumens, 5800K CCT
Low: 600 lumens, 198 Hz PWM
Strobe: 8 Hz
Parasitic drain when off: 98 microamps.
Next, I need to do a runtime/temperature test.
BTW, my SRKs measure 1885 lumens on high and 200 lumens on low. 6400K CCT
Edit: here is a plot of an 18 minute run. Temperature reached 62C and lumens dropped 420 lumens down to 1400 lumens. Color temperature went up around 160K
Looking forward to more measurements.
Do you think you have the same as driver as the other Kungs? (not sure if they are equal anyway though, even if they look the same)
How is perceived brightness compared to the King?
18W in, 1920 lumens out. Over 100lm/W OTF.Nice. A bit underdriven in stock form though. Needs more Coulombs/s. J)
Still waiting on mine, although I have not been to the mail today…
Edit: Ignore the first bt, based on pyro’s comment below. I was assuming the current and lumens were measured simultaneously, which was not the case.
I dont think the numbers add up.
If we assume tailcap= emitter current.
4,5A/4 emitters= 1,125 amps to each emitter.
Emitter lumens @ 25 degree would then be around 430 if those are real U2s. (according to Cree datasheet)
430*4= 1720 lumens.
I would not assume more than 1350 OTF at best with that current. Or am I missing something??
R86, your numbers make sense, and the efficacy I mentioned earlier doesn’t make sense either. Wishful thinking on my part I guess.
Pyro, any chance there’s a boo boo going on in the sphere o many mysteries?
Did yours also come with a loose driver and significant/more than average tightening pressure necessary to use protected batteries? Mine is a gold Kung, and I have no measuring equipment, but your measurements look like my scenario in relation to my SRK. I think my SRK is bluer, possibly brighter and low is definitely more than 200 lumen…so many variations, you never get what you expect!
The 4.5 amps was with a bench supply set to 4.0V (minus lead and contact resistance the driver was seeing 3.7V). At 3.8V on the driver it pulls 5.6A and at 3.9V it does 6.5A. The lumen measurements were with 4 fresh Panasonic 2900 mAh cells, so it was pushing more current.
Are you like the ‘Rich Texan’ character on The Simpsons?: ” ’merica’s not a place for seat-belt wearing cowards!“.
I know I know, risk of batteries going south is minimal, but I couldn’t help it, too amusing
I may actually try SRK with two or three unprotected from the matched high quality cells I got in a laptop pack: they are already matched and tested and not using 4 leaves extra room for compression in an outgassing event…plus in this Kung/SRKs I expect it to fail through the cheap driver to the wiring holes, through the emitter region: I think you’ll end up spraying whatever you are illuminating with glass but I doubt it would “explode” through the aluminum casing.
Interesting results. Thanks for posting them up. I would have swore that Dales Kung looked brighter than his King. Of course his King might be a little week, or his Kung a little healthier.
I have a Kung on route and will hopefully have it by weekend. I’m anxious to test mine too against a couple kings we own.
Tks for the numbers for everyone Texaspyro, kind of confirms my approximate no-equipment results, and from what I hear pain from heat does start about 130 F, your numbers were about 143 F, and mine gets uncomfortable to hold, not a real burn. Do you know if that kind of temp fries the LEDs quickly over time? I don’t really like it getting that hot, for the batteries sake. Its more of a turn on ‘low’, occasional high for me, still wonder if I have a bad one though, with the loose driver, blinky mode can only be reached from high when you press and hold, and it has to be very tight to turn on in the first place.
As for quality now, who knows, maybe Dale got one before they ran out of the “good” batch…maybe there are several factories producing them and one line is good, the others not so much to differing degrees. All I know is my Kung does not visually outshine my SRK really. But taking into account tints and flood degrees, it should throw out a bit more lumens, but nothing to wow over like his pictures show. Its a good handwarmer for the snow though
50C/122F is holdable, 60C/140F is not (for very long) This light got to 50C in about 9 minutes (temperature was measured between two of the fins on the head). The battery compartment was a bit cooler.
LEDs can handle over 120C chip junction temperatures without much problem. The question is what is the temperature difference between the flashlight case and the LED junction? A light with decent thermal design might be less than 30C. With crappy thermal paths it could be 100C…
Yeah its all a big ??? in my mind on the thermal design of this flashlight…with the modest increase in lumen output it SHOULDNT get so much hotter than the SRK… I think mine does get closer to 140 F at about 13 minutes, its painful and I cant hold it for very long and even by 9 mins I’m probably mostly holding battery compartment instead. There is a big difference in temp from the LED/switch housing and the battery compartment.
Actually, that can be an indication of a good design… hot bodies mean the light is transferring the heat away from the LEDs. The power input (based on tail cap current) is around what the SRK draws.
