Testing a Cree XHP50.2 J4 3A led

Flashlight Modding and DIY Parts
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A new generation of XHP50 from Cree, they called it XHP50.2 . The appearance of the led is in line with several other recently updated Cree leds, with rougher phosfor layer that is applied differently. Let's test it.

I bought two XHP50.2 leds from Kaidomain, of which the J4 3A bin is tested here, so a neutral 5000K tint. The J4 output bin is the highest bin in the datasheet, both for XHP50 and XHP50.2, but at this moment Cutter sells XHP50.2 leds in K2 bin (as often happens with Cree leds: higher bins are for sale than are in the datasheet) I hope that KD has their bins correct.

The led was reflowed on a 20mm KD-Light copper DTP board (6V configuration), so not my usual 16mm Noctigon, but in my tests I (and relic38 in his tests) never found significant differences between the various DTP boards around.

When a low 0.5mA current is applied to the led it immediately shows the new construction: the dies much closer together than the XHP50, and no dark cross. so the build is similar to the XHP35, which does not suffer from donut holes. Also the rough phosfor layer can be seen, so probably no dedoming for this led!

I checked the beam at 50mA with a smooth C8 reflector and a light OP C8 reflector on top of the led, and indeed the beam is nice with a good hotspot without donut hole, something you never got away with with the last generation XHP50 :-) . I think the led was not very well focussed inside the smooth reflector because the OP reflector actually shows a tighter beam. Left smooth, right OP, pictures under-exposed to show the hotspot shape well.

The output test was done like all my more recent emitter tests. I described it in detail in my XP-L test. , with two minor differences that should not matter significantly for the results: I used my Integrating sphere no. II instead of no. I, and for the current I used a clamp meter, which appears to measure 0.1A lower than the power supply current-reading that I used before.

In summary: 1) just one led was tested, reflowed on a DTP copper board (KD-light 20mm) 2) I used my large version II integrating sphere with high quality luxmeter, 3) the output numbers and voltages were measured with the led close to 'steady state' for each current, so warmed up and settled, you should be able to get these numbers in a well heatsinked flashlight. Mind that these are output numbers of the bare led, in a flashlight there will be losses from light obstructions, lens and optic, 4) output is in 'djozz-lumen' defined as 1/550 of the output of my Sunwayman D40A on high setting, which I hope is close to the real lumen, but at least is consistent over all my emitter tests done in integrating spheres.

What can be seen:

-the output of this J4 bin XHP50.2 led is not all that better than that early XHP50 led that I tested in november 2015. That led did not come with a bin, but it can't have been the best bin that the XHP50 comes in at present.

-But it has its maximum at higher current: 10.5A, compared to 9A for the XHP50. So the thermal resistence seems to have lowered a bit (even though the specsheet does not show a different number: 1.2 degC/W for both XHP50 and XHP50.2). This is a tougher led!

-The voltage is significantly lower, by 0.5V at currents that matter (for perspective: this compares to 0.25V for single die leds). This lower voltage not only implies that it will draw more current in a direct drive situation (this led is dangerous direct drive with two li-ions in series!!!), it is also more efficient because of it.

Conclusion:

This XHP50.2 led is a real upgrade compared to the XHP50 led, not necessarily for the higher output (unfortunately I have not been able to compare leds with 'certified' correct bins), but it has a significant lower voltage which makes the led more efficient. It is also tougher at really high currents. But perhaps the most significant improvement is the absence of the black cross in the output profile, this led can be used in smooth reflectors without problems.

Now see if I can think of a nice mod with this led, I purposely did not test it to death for that (I checked the led after the test, it only lost 1% output from the abuse).

Thanks for reading! :-)

(stereo picture)

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Looks like 100 lumen per Watt at almost 40 Watts. :+1:
(6.6 Volts x 6 Amperes)

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I am waiting for the 4 I ordered from KaiDomain, along with a triple reflector to fit the scratch build I have sitting at about 90% completion in readiness. I made it to fit 2 of the 20700 cells, figured I’d try it on 2 of the B variant and then move up to the A variant if they handled everything well.

So, if I can get the amperage to the 3 of them what are we looking at, some 15,000 lumens? Interesting…

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Thanks for testing these djozz, great info.

Low vf brighter and no cross= excellent

I noticed at cutter electronics in aus they have J4 in 1A tint and the brighter K2 1D tint in stock.

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Great test. I don’t have any XHP50 leds just an XHP70 in my L6 but I think about the XHP50.2 to put one in something. Maybe raplace the MT-G2 in my Small Sun Zy-T08.

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Again djozz invaluable information. This is a real improvement over the older led. Thanks for taking the time to do this. :beer:

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Ah, sorry, in my excitement over seeing your charts I forgot to say THANK YOU! :slight_smile:

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Could you test the tintshift and throw gain with domeslicing?

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I’m going for practical. Even in small lights 3000 lumens could be possible and still have some run time before the batteries drain or the host melts. 6.3 volts 3.9 amps 24.57 watts, not to shabby.

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Very nice test, I was thinking it should be around 5k lumens, although I was hoping for a bit more.

The real issue with this LED is actually using it in a flashlight. I can’t think of any driver options that would work with it right now. It would need a buck driver for sure an FET driver could try to push a buttload of power though it. It is possible that PWM it from a 2S setup would be ok like in the xhp35 but it is not ideal.

With these new low Vf LED’s on the market a good high current buck driver is becoming a must.

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Excellent, thanks for testing and sharing :+1:
I have a couple of these in the mail.

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FX-30 ?

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If you want it in an L6 (which I am considering) then yes but outside the L6 or S70 there are not exactly a lot of host options for drivers of that size.

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Nice review djozz

So no more dark + in the center. I wonder if this out throw XHP70 in convoy L6 in smooth reflector.

Can u test it out if it’s no trouble :slight_smile:

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I have no L6, I do have a Thorfire S50 doing nothing, I could have a go at that one, but the reflector is OP.

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Yeah, it’s a biggun…
Off topic, but can the FX30 handle 3S batt. config?

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Yes, it should vastly out throw the XHP70. I have an old XHP50 in a much smaller ~60mm reflector and it has a much tighter hotspot then my L6 but it has a cross in the beam, even with a shaved dome so it doesn’t get used much.

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Great test again, djozz!

The best improvement is the much better beam, I think. steel also posted some beamshots here: The new LED XHP50.2

I hope I can make some with a deep smooth 52mm reflector and a Ledil Crystal optic next week.

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What about using a current limited driver like the LD3 set up for 2S with a max amps of 6 or 7?

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Simple enough to use an FET Zener modified and use something less than a top cell so that 10.5A isn’t surpassed. Should be pretty easy with the GA and MJ1 and such out there. Or the 20700B.