Testing a Cree XHP50.2 J4 3A led

Yes, but that’s when you use the zener in prallel, and that’s to be expected.
What i’m proposing is putting a 3.0 Volts zener in series (but the ‘wrong way around’) in stead of the 220 Ohm resistor so you use its reverse voltage drop.
It will then just eat 3.0 Volts of 6.0 to 8.4 Volts, so that when battery drops below 6 Volts, the MCU will think it’s 3.0 Volts and starts blinking in low mode.

[edit] i suppose “reverse Vf” is called Vr :slight_smile:

Yeah, and you still need a 10Uf on C1. The Zener likes having it’s own 10Uf for stability, but the designed C1 I always populate too.

I’ve used a 39K at R1 but got away from it by changing the firmware.

This is getting a bit off topic i guess…
But my idea is to avoid SMD soldering as much as possible, so i’m thinking about using a fixed 3 volts voltage drop in stead of a 220 Ohm resistor and the parallel Zener.
You can obtain 3 Volts drop with 5x Si diode in series, but that’s a but bulky…
So i though about using a 3.0 Volts Zener in series, that is, if they even exist… :person_facepalming:

…more on topic, i superimposed Djozz’s XHP50.2 test graph on Djozz’s XHP70 test graph:
.

The XHP50.2 is plotted in green.
More on the XPH70 test: Cree XHP70 up to 4022 Lumens and XHP50 up to 2546 lumens - Multi-die leds. - #576 by djozz

Nice work Jerommel.

Basically what I figured, the xhp50.2 should give the xhp70 a run for it’s money without a donut hole. Not a bad LED option for sure if we can find some drivers capable of driving it properly.

I think I will buy one to try in my L6 which is bumped to 7.4A. And I have a SMO reflector for it.

I have a couple stock SD75’s with OP and SMO reflectors, FETDD drivers, LD2-3 at 12 amps that I would like to try this in, but is 5000k the highest tint/kelvin/temp out? If possible a link to it would be greatly appreciated.

Alternatively, could there be a special FET MCPCB that would mount to the driver side of the LED shelf? Starting from the front of the light, there’d be a sandwich like this:

LED
LED MCPCB
LED Shelf / Pill
FET MCPCB
FET
Airspace
Driver

with a couple of small bolts keeping the FET MCPCB in place, and suitable amounts of thermal compound.

This assumes enough space in the driver cavity, of course, but it might help to avoid space problems on the LED side, given that reflectors / optics tend to sit quite close to the surface of the LED MCPCB, and the LED itself sits so inconveniently in the middle :slight_smile:

It also allows the use of any stock LED MCPCB and keeps the FET gate wire wholly inside the driver cavity, if that makes a difference.

Anybody already tested these drivers?

http://www.kaidomain.com/p/S025265.FX6-22mm-6V-8_4V-5A-4-Mode-Driver-Circuit-Board-for-Cree-XHP50-XHP70-MT-G2

http://www.kaidomain.com/p/S026506.FX6-22mm-6V-8_4V-5A-4-Mode-Driver-Circuit-Board-with-Side-Switch-for-Cree-XHP50-XHP70-MT-G2

5A is not too bad, imho.


Jerommel has given the graph an incorrect fuzzy title (although he did refer to the origin of the graph where the correct information can be found). The title says that the the XHP70 test was ‘in less than ideal circumstances’ while in fact in the graph two XHP70 tests are to be seen, of which the purple one is wrong and must be ignored (the led was reflowed on a bad performing makeshift board), the red graph is correct, on a quality copper DTP board, under as perfect circumstances as I can create them.

I always make a point of giving my graphs headers that describe the contents as complete as possible so that they can be copy-pasted without loosing their context, but Jerommel (unintendedly), by writing a new header, has removed that context here.

I have an Acebeam K60, if I install this led and according to the graph I would lose around 600 lumens but gain more throw? Doesn’t sound like a bad trade. :heart_eyes:

It’s a disclaimer actually, because it’s not made by you this way, not based on your measurements but by image manipulation done by me.

of course.

You wrote the red line represents an abused LED (resulting in higher Vf and lower output, but on a proper MCPCB) so i wouldn’t call that ideal circumstances either.

I love the charting, the information it imparts, the graph showing all the pertinent aspects give a great idea of what to expect…

However, I have an XHP-70 in a Convoy L6 making 7245 lumens at 11.97A, far above the plot and respectably higher than the XHP-50.2 shows. Not sure then how to interpret the graph.

While I do have 4 of these 5000K 50.2’s on the way, the main plan is to build 3 of them into a triple. I don’t know quite yet what I’ll do with the 4th, perhaps put it in another L6 and build the same ramping driver as the other for a direct comparison?

The problem with this is that it would not work with all hosts, only those that have a thick enough shelf to allow a screw to be used to mount the bottom side mcpcb among other issues. If you were desinging a light from scratch there are lots of ways to power the xhp50.2 but in a retrofit setup we are much more limited and need a more universal option.

A good preforming buck driver is the best idea but the best we have at this point is the mtnmax with ~5A.

Your xhp70 is a P2 bin where the one djozz tested was an N2 bin, that explains the bulk of the difference in readings.

Also his readings are “hot readings” and yours are turn on / 30 second readings. I notice big jumps in output from a cold start vs a steady state test, easily explaining a large part of the remaining difference.

The final ~5-10% would simply be sphere calibration differences.

Does raise the question though, if one should do a graph based on ‘hot readings’.

…is the post with the corrected XHP70 led.
@Jerommel: it used the same led as the first, imperfect, test, and it does state that the led had suffered somewhat, but the few % that that mattered can hardly be called less than ideal.

@Texas Ace: thanks for the explanation, but if you add that all up you still do not get to Dale’s numbers comfortably: in the above linked post you can find a cold start test as well, at 12A/30seconds that led did 6024 djozz-lumen, the difference between P2 bin and N2 bin is a factor 1.15, so that makes 6933. In my experience OTF of a common ok quality flashlight (without super fancy reflector and lens) you loose about 18, so that makes 5685. That makes Dale’s reading 27 higher than mine.

But that does not really startle me anymore btw, the few attempts (texas pyro, sma, Zweibrüder integrating sphere and Texas Ace) that I made to compare different people’s calibrations, in most cases showed way larger differences than I expected and wished for. I was within 1% of sma, 9% over the LedLenser sphere, can’t remember tp but it was between 20 and 30% different, and between TA and me it was 5% or 20% depending on which light source :confounded: )

Yes, that’s the post i linked and took the graph from.

Perhaps you use a fuzzy incorrect definition of “ideal”. :wink:
In the red graph the Vf shouldn’t be higher than in the purple graph (at least, not below 4.5 Amperes or so, should it?), and the output in the red graph should never be lower than in the purple graph.
This way the result is that the green XHP50.2 graph looks better (compared to the red graph) than it should.
(doesn’t it?)

Either way, i did it just to illustrate things, but with keeping the circumstances of the XHP70 test in mind.
Maybe i should have written: the state the XHP70 was in, was not ideal in the red graph.

@djozz - Thanks for the thread! Can the XHP50.2 be a direct replacement for XM-L emitters? (I'm thinking yes due to the exact 5x5mm base but not sure about the connections)

Also, any tips on perfectly centering the emitter during an upgrade? I saw your home made reflow thread and am potentially interested in making one. After so many years, decided to finally try a little modding... :P