Finally the XHP70.2 emerges!

[luminarium_iaculator]

@Enderman

If I need a flashlight for work or EDC I buy a factory assembled light with enough lumens and throw.

Imho most factory assembled light sucks… And that counts even for some “premium” China brand manufacturers.

[djozz]

@djozz

Tom, since your ledboard was not soldered down either, I will do a re-test in my usual way without soldering the board. After the test I pulled the led off the board and back on, that may have improved the reflow a bit. Also, I will use larger stiffer rings under the screws so that the pressure is more to the center of the board.

Maybe tonight but it can be later as well.

So I re-did the test with extra emphasis on getting the mounting right. I did see some improvement in the numbers: slightly higher voltages and the maximum is now 6860 lm at 12.5A, but from there it goes slowly but steady down again.
After a complete cooldown I will try a 15A and a 20A burst but I’m afraid that I will not get to the previously reported results.

I’m not sure what to do with this, I may have a particularly low performing led, or perhaps one way or another my test method is not suitable for such high powers. I’m reluctant to post emitter test results that several others have found to be not correct.

[EasyB]

djozz, it is troubling when different measurements don’t agree. Back when the XHP70 came out and you measured it there were also discrepancies between your measurements and measurements done in a flashlight at turn-on. Then you took some measurements at turn-on and that cleared up the discrepancy, right?

Cree XHP70 up to 4022 Lumens and XHP50 up to 2546 lumens - Multi-die leds.

I tested the XHP70 again last night, now mounted on a XHP70 Sinkpad, with the romantically wandering traces avoided by scratching some masking away, does not look pretty but it works alright. What is most important is that the thermal path of the middle pad has improved compared to my makeshift board using a XM-L Sinkpad and copper bits. [image] It is the exact same led as the first test and I plot the results together the makeshift board results because that is pretty interesting: at high cur…

I’m interested to see your results.

[Tom_E]

More goodies:

Little pricey but if you wanna play...

Hoping for 3 of these to go in my MT03.

[KawiBoy1428]

Just to satisfy my curiosity I put the 70.2 P2-1A JAX X6 (18-20amps) using a L6 OP reflector against a L6 70 P2-1C (12-13amps) OP reflector and on the meter and visually (side by side) the 70.2 P2-1A “Out Performed” (stunningly) the old XHP70 P2-1C, as apples to apples as I can get!

Carry on…… :+1:

[djozz]

@EasyB

djozz, it is troubling when different measurements don’t agree. Back when the XHP70 came out and you measured it there were also discrepancies between your measurements and measurements done in a flashlight at turn-on. Then you took some measurements at turn-on and that cleared up the discrepancy, right?
Cree XHP70 up to 4022 Lumens and XHP50 up to 2546 lumens - Multi-die leds. - #576 by djozz

I’m interested to see your results.

Bare led results for going directly from 0 to 15A and 19A (the PS did not go higher) starting with the led at room temperature:

15A: start 8015, 30seconds 7400
19A: start 7780, 30seconds 6070

Also not really different from my first test, my XHP70.2 led in my test situation does not like going over 15A, warmed up 12.5A

[EasyB]

Hmm, hard to say what the source of discrepancy is. One thing is that Kawiboy and Tom measured the current with a clamp meter. Depending on the resistance of the tailswitch, the current when the light is in normal operation could easily be 1.5-2A less than with the clamp meter. So if they did the lumen and lux measurements with tailcap in place that could bring the measurements a little closer.

[KawiBoy1428]

I put the 70.2 P2-3B in the SR90, I think I finally found the emitter that suits this Bowl type of a reflector well enough to finally leave it be!

Now only battery pack will have to be rebuilt and upgraded, one day, some day? :person_facepalming:

[Tom_E]

@EasyB

Hmm, hard to say what the source of discrepancy is. One thing is that Kawiboy and Tom measured the current with a clamp meter. Depending on the resistance of the tailswitch, the current when the light is in normal operation could easily be 1.5-2A less than with the clamp meter. So if they did the lumen and lux measurements with tailcap in place that could bring the measurements a little closer.

That's true for me. I could measure lumens with the tail jumpered with same wire used with the meter.

[djozz]

I’m not too concerned about lumen differences, ordinary calibration differences could explain that already, what is the real worry is that Tom and Kawi found a very significant increase in output between 15 and 20 amps, and I see a clear drop.

[Tom_E]

Across 4 measurements by KB, post #108 here, it certainly does show consistent rise in output from 15A to 20A. I should get some more data points in this range as well. I only tested at 11A and 18A here at post #94.

[djozz]

I will just give up for the moment, a proper re-test would require a new $16 dollar led that takes weeks to arrive, soldering a fresh ledboard onto a 30mm copper disc and mount that on my test-rig.

In the meantime I guess that over many people combined enough knowledge is gathered on this led that a test has little to add anymore.

[EasyB]

@Tom E

Across 4 measurements by KB, post #108 here, it certainly does show consistent rise in output from 15A to 20A. I should get some more data points in this range as well. I only tested at 11A and 18A here at post #94.

KB mentioned his lux measurements were with bypassed tailcap, so the amp values associated with those lux measurements could be 1-4A lower, depending on the tailswitch resistance (ranging from 0.01-0.035mOhms). So the lux measurements could possibly be over 12-16A, not 15-20A. This could potentially explain a big part of the discrepancy with djozz’s measurements.

[Tom_E]

I get higher lumens measurements with the tailcap on consistently over the bypass wire, 3 times out of 3 with 3 different sets of cells. Not by much but between 100 and 200 lumens. I use a 14 AWG bypass wire, 8" long between the batt- and the end edge of the tube.

Good switches are pretty efficient and you have a stronger ground contact in the assembled, threaded tailcap, plus a 20 AWG bypass for the spring.

[EasyB]

@Tom E

I get higher lumens measurements with the tailcap on consistently over the bypass wire, 3 times out of 3 with 3 different sets of cells. Not by much but between 100 and 20 lumens. I use a 14 AWG bypass wire, maybe about 8” long between the batt- and the end edge of the tube.

Good switches are pretty efficient and you have a stronger ground contact in the assembled, threaded tailcap, plus a 20 AWG bypass for the spring.

Interesting, thanks for the measurements. But they could be interpreted in different ways. It could be that you are actually getting higher current with the tailcap. Or it could be that you are getting less current with the tailcap, and the output is higher because you are in the downward slope portion of the output curve.

I just did a quick measurement of contact resistance of a 12 gauge wire pressed on the edge of a 1.5mm thick copper disk, and with just a bit of pressure it was below 1mOhm. So unless your 14 AWG wire end is unclean the contact resistance is very low. The 8” 14 AWG wire has about 1.7mOhm by itself.

I have measured bypassed-spring tailcap and switch assemblies and they have ranged from 10mOhms to 35 mOhms.

[Tom_E]

I have solder blobs at each end of the 14 AWG wire. Dunno, could be some degradation, I've had it happen before on jumper wires - resolder, and get higher readings. This one has been used a lot.

I hear the theory but in practice, I've seen over dozens and dozens, maybe 100's of measurements where the tailcap assembly does better, pretty much every time. Granted many don't have a switch (e-switch lights with no tail switch). So maybe my wire ends are beat up. I got plenty of wire around, so maybe I'll make up a clean new 12 AWG jumper and compare.

I'm surprised the surface contact area makes no difference in the formula? With the tailcap you get the full circumference of the tube making contact even with an anodized threaded tail, while the wire has a tiny fraction of that for contact.

Update: I just cut a 10 AWG stranded coated wire (all I use is stranded), 6", soldered the ends, cleaned up the ends with isop. alcohol - same result: jumper wire has lower lumens readings every time compared to the L6 switch assembly - repeatable, went back and forth a few times. Not much of a difference but I'd say about 60 lumens.

[EasyB]

The way I measured the tail cap resistance was by passing a known current from the (bypassed) spring to the point where it would make contact with the battery tube. Then I measured the voltage at these two points to find the resistance. So any contact resistance between the tail cap and battery tube would be in addition to that resistance, but I think the contact resistance would be very small.

With your updated measurements I would say there is almost certainly more current flowing when you bypass with the AWG10 wire. There is just no way there is more resistance (contact resistance included) than in the tailcap. If that is true then that means you are at or near the maximum in the output curve.

Could you try the same measurements (with tailswitch and with AWG10 bypass) with a single XPL light? In this case we would be on the upward side of the output curve, and you should see more output with the bypass. (If my understanding is correct)

[Tom_E]

Ok, tested the 10 AWG wire across 3 different FET based lights, and again with the L6 at lower amps, about 12A. On the L6 the wire makes little difference. Have you seen an L6 switch? It's huge! Believe it's on of those 6A rated switches.

On the other lights:

• U21 w/dedomed XPL, no tail switch: wire does slightly better (~7 lumens out of 1,600)
• Warsun X60 w/XPL2, tail switch: wire does much better (~190 lumens out of ~2,000)
• Lumintop SD26 w/XPL2, no tail switch: wire does slightly better (~30 lumens out of ~2,100)
• L6 using EVVA cells, about 12A @tail: it's about a draw over 3 trial tests, all within 1% one way or the other (~7,300 lumens)

So for a bad switch, like the X60, can be a big difference. The L6 has one of the best switches we have available to us though.

All the more reason to get rid of the tail switch . If I get around to upgrading the X60, I'll look at eliminating the tail switch - don't need it with NarsilM.

[Texas_Ace]

@Tom E

So for a bad switch, like the X60, can be a big difference. The L6 has one of the best switches we have available to us though.

All the more reason to get rid of the tail switch . If I get around to upgrading the X60, I’ll look at eliminating the tail switch - don’t need it with NarsilM.

You can simply bypass the switch like we do the springs. Or just bypass the spring directly to the outgoing side of the switch.

[Tom_E]

I modded a couple X60's for BLFers, but not sure what I did - probably swapped out the switch - that's what I usually do when I see a significant drop from it. My own stuff though always gets lowest priority - I never seem to get back to my own to improve it.