I do my testing with a similar branded bench supply. I dont use the readouts on the power supply itself but measre at the led as there is a slight difference between readings. The readings on my power supply are as accurate as my DMM's.
Measure voltage across the emitter with a DMM and compare that to what you get at your PS.
On a de-domed U4 1C in my modded Convoy L2, I measured 5.47A at the tail using my new clamp meter on a Basen 26650 4500 cell @4.22v, and DD FET driver.
On a modded BLF Lucky Sun D80 on a 30Q @4.21v: 5.15A tail (DMM), 5.36A tail (clamp), lumens: 1812 @start, 1744 @30 secs, 52.5 kcd (taken at 5m)
Don't have the exact #'s but on a XM-L2 T6 4C FET+1 driver Warsun X60 mod, I measured bout 6.5A tail on a DMM, and over 7A at the tail on a clamp meter. This is with an EFEST 4200 26650 or the new Basen 4500 26650, both at about 4.21v or 4.22v..
You should be getting between 5.0A and 5.5A on a U4 1C with a decent DD FET driver using a clamp meter (the UT-210E). As shown above, a clamp meter will always get a higher reading on a DD driver. On the high Vf U3's, I get in the range of 4.0A to 4.3A with a similar setup.
Your amps measured are consistently lower, so I'd suspect either the measuring method or higher resistances in the circuit (driver, host, wires, possibly MCPCB/LED, etc.).
RMM,
Just now I did as you suggested and measured the VF with my DMM using the same test emitter as before. I got 3.99 @ 4 amps. The PS reads 4.1v so I am getting a slight variance there.
TomE,
Thanks for chiming in.
Where you said
"You should be getting between 5.0A and 5.5A on a U4 1C with a decent DD FET driver using a clamp meter (the UT-210E). As shown above, a clamp meter will always get a higher reading on a DD driver. On the high Vf U3's, I get in the range of 4.0A to 4.3A with a similar setup."
That is fairly close to what I was getting wtih the U4s until recently. I dont have a clamp meter but I use heavy custom leads for my DMM. On a 26650 light I was averaging 4.4-4.8A on 26650 lights and just a little under that with 18650 lights.
These new ones wont squeak out anything above 3.8.
Measured directly at the emitter solder points?
Yea, not sure, we could be splitting hairs. My heavy gauge DMM leads soldered direct into the banana plugs does fade over time. I found treating the banana plugs w/NO-OX-ID gave me a bump, refreshing the solder tips of the heavy gauge wires also gave me a bump, then NO-OX-ID on those solder blobs helps more.
I havent' seen a dramatic drop in U4 1C's, but can't be sure when the U4 1C's were bought, or what batch - got some from MtnE and maybe IOS, both fairly recent though. The U4 1A's from Cutter I believe perform in the same range - only tried one and blew it out in the BOSS1, but probably went over 5.5A.
light-wolff,
Correct. At the solder points on the MCPCB.
TomE,
I'm just glad others are chiming in. Especially since you also have very similar results with the U3 bin and the higher VF. The more and more tests I do, and the more information I get here the more I suspect that I was shipped U3s by mistake.
I think if RMM gets results from his stock that reflect my original test results I will just end up order new emitters from him.
Think'n that could be correct - performs like U3's...
I've only found out very recent how low the U3's are compared to the U4's - had no idea. Really very disappointing for me because I just bought recently qty 10 of U3 3D's from IOS, and still have a bunch of U2 3D's thinking the U3's would be better. Like the tint but but being 1.0 to 1.2A lower than U4's is an additional penalty for that tint.
Slightly off topic, but ate you guys finding U4 bin to have a higher brightness than v6 when using a FET driver, all else equal?
Barring the evidence we apparently have, why and how could there be such a significant difference in the U3’s? After all, isn’t the U3 just a bin they assign after manufacturing? Were the U3’s all from a single batch that somehow got messed up with a higher Vf and Cree just deemed them good enough for rated spec?
Yes - I'm finding the U4's brighter than V6 XP-L's. Umm - diff in U3's? Well, newer T5's, U2's etc. are also low amps and high Vf like the U3's. U4's on the other hand seem to be different.
The bin assignment was theoretically that: pull the LED's off the line, test them, throw them into the appropriate output bin. But, we don't really see this - within a given time period, what we are allowed to buy, released to our somewhat gray market, is very specific tints in very specific bins. A bin though is a wide range, so maybe the CREE manufacturing process is so precise now, you don't get diverse bins spreads.
Cant really say why and how for sure. I know that around the T6/U2 bin something was different with the bond wires. Driving those bins to 6 amp was no problem. When we hit U3 I not only noticed the spike in VF, I also found that the bond wires would fry at lower current.
This is just an observation. I use about 400-600ish XML2s per year so its hard to judge exactly what is going on for say a reel to reel basis and such.
The bins are all bout efficiency - lumens/watt. I think CREE made a design change to get higher efficiency in the U4's and may explain why the Vf is lower.
Any discussion of measurement methods here is a moot point in my opinion. As long as the results consistently relate to one another (apparently they do) all the questions like “did you take the readings from your DMM or the PSU” and “did you put the DMM right on the LED” become irrelevant. While in our hobby a difference of 0.1v due to measurement method can be very relevant, that’s not the case here. As long as the method remains consistent the results compare properly to one another. VOB’s measurements on one set of emitters are repeatably lower than on another set. At the end of the day it sure sounds like a bad batch for whatever reason since nobody else has chimed in to say “oh I had that problem too!”.
RE the binning vs manufacturing methods conversation… as mentioned above, the waters are really too murky from our perspective to draw strong conclusions but it stands to reason that a lot of what we see is based on how few LEDs actually flow through the grey market. When we notice something like “U3’s have a high Vf” what is possibly more accurate is that the U3 bin required a higher Vf when it was a new cool-white bin. That’s happened before with other LEDs, bins, and manufacturers too. After whatever advances led to the U4 dropped the Vf back down this probably also applied to any new U3 production. Without a date code on some modern U3’s it’s impossible to say. In other cases Cree has come up with a new technique and then applied it where they could. I could be way off base here, and I’m definitely not speaking based on personal experience with either bin (as many of you can guess, hehh).
Here’s my 2 cents. Built a Convoy C-8, with all the tweaks, FET driver, and VTC 5 cell. With a hot de-domed U3-1A (from Richard I believe) pulled around 4.3a. Removed the U3 and replaced with a hot de-domed U4-1C, from Richard, and amp draw went to 5.1-5.2a. Lux increased 20-25kcd. I did this a few weeks ago and forgot the exact numbers, but I’m close. Not overly thrilled with the 1C tint. Awaiting delivery of some U4-1A from James@ 3Tronics. If the 1A has the same output as the 1C without the yellow tint, I will be very happy! BTW my current measurements are done with my Fluke 336 clamp meter.
Hi, my last build is a Convoy M1 + FET 1 driver (from bangood) Noctigon Xm-l2 U3 1A (from IOS) and i´ve got 4,3 amp
The battery is Pananasonic/sanyo NCR18650GA 3500mha and ths springs are in stock form (not bypass)
How much amps can i got with a better battery (less resistance) and springs mod?
Hope this help.
Alberto.
Usualy 4.7- 5amps, FET+1 driver from BG isnt a good option though, it has tons of issues: the best battery for a DD fet driver atm is Sонъ VTC5A or if you want best runtimes Samsung 30Q
What´s the issues with the Bangood fet +1 driver?
Anyone know a better springs (Beryllium copper) or similar for flashlight that will be better than the stocks (convoy m1 and BLF A6 Fet + 1 driver) ?
Thanks in advance.
Alberto.
Djozz did some interesting work re. springs here:
I use the Fasttech ‘carobronze’ springs to avoid the need for a wire bypass.
Not the best, but much better than steel springs and does not heat up at moderate-high currents.
https://www.fasttech.com/product/1347100-batterydriver-contact-support-spring-for-flashligh
Big issue with the A6 drivers is probably the off-time cap and related firmware. The short/medium/long press duration all gets stretched as driver board heats up. Build quality may also not be consistent. I tried a few and they are OK, but this is with my own firmware and not using the OTC. One pleasant surprise was that the stock wires are silicone-insulated and the spring is non-magnetic (so not steel).
Anyone knows what metal is used for the springs on these drivers?
I believe what Mitko is talking about is high resistance and low amps, compared to other DD FET drivers.