Yezl Y3 - a picture breakdown

Both came from MTN. That would be a really huge bummer, but it would explain a lower-current-than-expected problem I’m having with an Ultrafire F13 I modded with the 22mm 16x7135 linear driver. Can’t remember exactly what I measured it at… but I think it was in the 3-4A range. I figured the DMM was acting up - got pretty hot on high.

Edit - I’ll test the Y3’s with a pair of unprotected NCR18650PFs in the morning. If I can make it that long — awfully tempted to get out of bed to see if that’s the issue. Gonna suck if the $35+ I spent on 3 of those 26650’s was wasted.

Wow - never saw a stock DMM measure high amps, like over 3A reliably, even a Fluke, but you may have a winner there but I definitely would not trust that setup for regular use. I've seen this before - guys thinking their stock leads work ok, and once they get heavy leads, their eyes open. If they are really good (doubtful), then could be other things as mentioned - cell, bad resistor, etc., or something different about your driver vs. mine. A light meter is always a nice way to verify things to see relative effects.

There are multiple EVVA unprotected 26650 Mtn sells - which exact one? If it's the 5200, it's pretty low performing compared to the re-labeled KK 4000. I'm staying away from those 5200's. The 26700 cell is even higher capacity and high performing (mine measured at 5300-5400+) - win/win, and fits the Y3's that I have.

I measured the CNQ AR vs. stock lens last night - AR is slightly less in diameter, maybe by .05 mm, close...

Definitely DMM stock leads are the problem.

Dunno - I'm not saying it's impossible that DMM w/leads would work well, just very hard to believe. Thought we've been down this road many times before, and it always (like 100% of the time) ends to find out the stock DMM leads are N.G. - may seem to work on some setups/lights, but not all - after many posts back and forth and time spent, turns out to be poor high resistance leads...

Again, I got 3 DMM's including a Fluke, and all stock leads and extra leads I've bought fail to measure high amps reliably.

Ohhh - also, it's important what high amp setup youv'e been measuring ok in the past. if it's more than one cell in series, totally different animal. If you say voltage was in the range of 3.0 - 4.0, then that's different.

grantman321 wrote:

Y3 #1 – Stock driver, stock driver spring, dedomed stock LED on stock mcpcb, one fresh EVVA 26650 (unprotected): 2.25-2.30A

Y3 #2 – R100 added over R150, stock driver spring, stock LED, 22ga LED leads, one fresh EVVA 26650 (unprotected): 2.60-2.65A

Both Y3’s from the cnqualitygoods GB.

And for reference…

Convoy S2+ – 3.04A Qlite flashed with NLITE (8×7135’s), stock springs, solid copper spacer soldered to brass pill, 3-up dedomed XP-L V5 2As on noctigon, 22ga LED leads, fresh NCR18650PF (protected): 3.05-3.10A

I was beginning to think it was a faulty DMM for sure… now I have no idea what to think. Could there be THAT much resistance in the driver spring or did I draw two unlucky straws with the drivers in my Y3’s?

Hi grantman321. I'm assuming those are tailcap measurements and that the Y3 driver is a buck driver. It's pretty normal for buck drivers to deliver less current with one cell. I think it's because they typically require more overhead voltage (Vdo). So less voltage is available to drive the emitter and therefore the emitters allows less current to flow. Buck drivers work best with 2 or more cells in series.

I don't have time to read all the Y3 threads. Has anyone else reported tail current on 1 cell with the stock driver?

Well, I tested the lights over again with unprotected NCR18650PFs and got similar results - and then again with another unprotected EVVA 5200mAh 26650 that I ordered separately from the first two. Still getting roughly the same results for each light with a variation of about +/- 200mA between different batteries.

I’m not arguing at all that my DMM leads aren’t the issue — I assumed when I bought a $20 DMM that it wouldn’t be perfectly accurate and reliable out of the box — accurate enough for rough estimates when testing mods was all I was shooting for there.

So as of now, I have no reason to believe the batteries are the issue — gotta be either the DMM or something screwy with the drivers in the Y3’s I got. Still not quite understanding how it could measure some single-cell lights with relatively accurate results and others way off from expected. All of the batteries tested were between 4.10 and 4.18V resting, and all tested in the same manner, with the amps I reported being a rough estimate of the average after it settles down over a few seconds.

I don’t think I’ve ever actually tested a multiple cell light with this DMM before. I only have one two cell light that I use regularly (a modified Convoy C8 with a zener’d Qlite +4x7135s), and I know roughly what the current on that light ought to be, and the light works great so I’ve never even bothered to test it.

Bottom line… I need to figure out how to get this DMM set up right and then go from there. Are there any writeups on BLF about modifying budget DMMs for better accuracy?

The leads have resistance and resistance cause a voltage drop if you measure current. This dropped voltage is “stolen” and less voltage gives different current.
How the lower voltage behave on a driver depends on the driver.
The stock y3 behaves like that:
4.2V gives 2.3A
4V gives 2.4A
3.8 gives 2.6A
3.5V gives 2A

It’s regulated to some point(around3.7V) and after that power drops.

I just plugged it to a power supply and noted the display current and voltage which is not absolute accurate but enough to enlighten all the differences in tail amps a bit.

I bought 14 AWG silicone multi-strand high temp wire and directly soldered them into bare DMM connectors. On the other ends, I strip off bout 1/2 inch then solder the exposed ends up so it's stiff and chunky. The 14 AWG silicone is 12" long, nice and flexible, easy to work with, but not too long - again, longer it is the more the resistance. I bought the wire here: http://www.buddyrc.com/black-14awg-silicone-wire.html and red, cheap, good quality -- probably best deal around actually on wire at BuddyRC.

For the connectors, dunno - I got mine @work, but you could buy a spare set of leads cheap ($3 - $7 eBay, FastTech, etc.) and cut off the wires.

This is a sweet cheap DMM I have: http://www.fasttech.com/products/0/10002748/1483104-uni-t-ut33d-1-9-lcd-palm-size-digital-multimeter, but I leave it on and kill the battery all the time. So I bought this one: http://www.fasttech.com/products/1004/10002748/1204400 with a battery saver, and 20A capable Wink.

Well I made a few mistakes with the Y3. Wanted to put in a MTG2. First mistake was buying protected batteries for it, well they don’t fit at all but enough to get power through. Can only screw it up 50%. Once I got everything together the beam was just too tight for my liking, I should’ve known this though based on everyone else’s comments. I did double up a R100 like the rest of you. Output was good but it produces too much heat too quickly to be something I want to carry around. I still prefer my older resistor-modded TR3T6 which floods more and is brighter to my eyes.

Anyway took the G2 right out and put the XML back in. Back on the shelf for that light probably!

Oh and instead of shimming the G2 up, I ground down the head of the light at the base. This allowed me to screw the pill further into the body and press up against the reflector, eliminating rattle and pressing the MCPCB against the aluminum.

grantman321 wrote:

. . . Bottom line… I need to figure out how to get this DMM set up right and then go from there. Are there any writeups on BLF about modifying budget DMMs for better accuracy?

I think we cross posted. Did you see my post 141. Your measurements are in line with Werner's measurements using a power supply (Post 143).

But in my post #132 I said I measured 3.55A to 4.0A with the R100 resistor added (just like grantman321's Y3) - Werner's is with no resistor mod. There is still a difference in amps measured between his R100 modded Y3 and my R100 modded Y3.

@ImA4Wheelr, Werner & Tom E — Thank you for the replies! So basically it seems to be reading somewhat correctly, and the R100 doesn’t have much effect when running the light on just one cell? I’ll desolder an LED lead on each one and see what the current is at the emitter with two cells in series. My end goal with these is to have one with an MT-G2 and one with an XM-L2, both on 26mm maxtoch mcpcbs putting out in the neighborhood of 4-5A on high. I’d prefer to run the XM-L2 on one cell, but if two is what it takes, so be it. I went ahead and grabbed two extension tubes when I got the lights during the GB anyway. What got me to the point I’m at now is I’m trying to get the driver as close to where I want as I can before going whole-hog and reflowing emitters and all that. Haven’t even braided the springs yet.

Still definitely going to solder in beefier leads in the DMM, it’s something I figured I’d need to do eventually and now seems like as good of a time as any. Y’all reckon a sizeable local RC/hobby shop would stock wires like that (high temp, low enough gauge)? My understanding of electronics is just marginally decent enough to mod lights with a small degree of competency — I hadn’t even considered the DMM leads would cause a voltage drop which would lead to different readings… I figured they were primarily limiting current.

@aoeu — the MT-G2 wasn’t floody enough?? I find it hard to believe it’d be less than twice as floody as a Y3 with an XM-L2. I’m kinda hoping for a decent balance between throw/flood with my eventual MT-G2 Y3. The Convoy C8 I’ve built with an MT-G2 is mostly all flood… doesn’t throw hardly at all compared to a dedomed XM-L2 in a C8. Hoping the much-larger Y3 reflector will be big enough to give it a decent balance with the bigger emitter.

Were you measuring with two cells or one?

aoeu - I believe the tube extensions are not sized correctly. With the stock light, a 26700 cell fits fine. With 1 extension, things get tight (maybe too tight) for 2 protected cells. With 2 extensions, 3 unprotected get very tight. Ugh.... You can see as you add extensions and cells, the last cell sticks further and further out of the end... This is sort of a disaster really for use of the extensions. Suppose you can mod something somhow to get some space back...

Edit: I'll have to look at that head base - bout grinding it down. Nice tip!

gman - I used one cell, clearly stated in post #132 ("one" and "a"), so we are still getting different results. Ohhh - my EVVA unprotected is a 4000 mAh (good re-labeled KK).

For the MaxToch 26 - I didn't finish it yet, but sized it up for the Y3 I'm working on, I'll have to re-drill one LED wire hole (poor positioning in the stock light) and possibly add a copper spacer to make up vertical space. I'll be modding the plastic alignment piece by cutting it down, then sanding the bottom to make it much thinner - it's way too thick now, keeping the LED further out of the reflector than it should be. It looks like the wires will clear the reflector bottom, so if the alignment piece is filed down, you can really get a nice positioned LED out of it -- meaning more inside the reflector.

if we add a resistor marked “0” will we gain anything ?

ImA4Wheelr wrote:

grantman321 wrote:

. . . Bottom line… I need to figure out how to get this DMM set up right and then go from there. Are there any writeups on BLF about modifying budget DMMs for better accuracy?

I think we cross posted. Did you see my post 141. Your measurements are in line with Werner's measurements using a power supply (Post 143).

Tom E wrote:

But in my post #132 I said I measured 3.55A to 4.0A with the R100 resistor added (just like grantman321's Y3) - Werner's is with no resistor mod. There is still a difference in amps measured between his R100 modded Y3 and my R100 modded Y3.

That's why I asked in my previous post if anyone has measured with one cell. I don't know what the difference is about. It seems like what you said about the stock DMM's leads could be a big part of it. Stock DMM leads become a bigger bottleneck as current increases.

"0" resistors are jumpers - same effect as jumpering a wire across the pads. So if you do that over one of the driver resistors, you are nulling out the effect of those resistors. I didn't try it - might work at high amps, might fry something because of super high amps, might simply fry something because the driver can't take it - a risk, unless you don't mind losing the driver and/or LED, etc. Maybe someone tried it already? Not sure...

thanks for the info TomE , i prefer not to take the risk :slight_smile: ,especialy for the driver will be very dificult to find another .

If someone mods this, please make some pictures so that I can just do the same without hassling around to much to find a good focus.

Werner explained this above, but it’s quite possible to measure high current with thin leads… as long as there is plenty of voltage overhead available. Between voltage sag and the relatively high sense voltage which these buck converters consume and the voltage dropped on the thin leads grantman321 has run into his problem. When he measures 3A or 4A on a linear driver he’s probably using a very strong cell (doesn’t drop much under load) and a relatively low Vf emitter and just barely getting away with it. As you guys have all already mentioned, the problem is certainly going to be the leads. I just thought I’d expound on why grantman321 may have gotten away with 3A measurements.

An exaggerated example:
Stable 5v input for 3v output means the linear driver “burns” 2v. If small multimeter leads “burn” 1.5v, there is no perceptible difference at the 3v device. Current remains the same, output remains the same, and heat generation at the linear driver is reduced. Using the same setup with a 4v supply you’d notice a drop in output when you inserted the multimeter.