I'm only achieving 2.25A from a 3.04A driver

Ouch. :(

Did you use the ammeter in place of the tailcap? If so, that's a hint that the meter isn't the cause of the low amp readings.

Jumping LED- to GND won't hurt a thing on that driver, it just bypasses the current-carrying section of the 7135s.

Nope I was trying it with the tailcap on first
But it’s the LED that fried I’ve already checked it so
Mistakes cost money good mistakes “lessons learned” cost even more

Ah man that sucks, frankly I don’t feel comfortable recommending doing direct drive tests exactly because of this possibility.
Depending on the type of cell and the resistance in the circuit you can pump some potentially very dangerous current through the led. I know we can all get complacent with seriously overdriving these leds because usually they’ll take it fine. But any time we push them above their maximum current rating we’re flirting with the possibility of a dead emitter.

XM-Ls are tough but not invincible and imho direct driving should only be done if you have a bit of experience with the setup and you’re happy to replace the led should it go pop. Maybe we could just add a little disclaimer in future when we recommend a DD test to someone who may not be aware of the risks.

I might have to make that last line my signature
Atleast I know I got batteries that can push some current

I should have elaborated more. I’m speculating that an errant conductive source may have caused an inadvertent and unnoticed short on some of the driver contact points in the process. Proabably worth checking before throwing a possibly good emitter out.

Driver is still working great
I just soldered it up to a pt54 red LED
I know it can handle whatever you throw at it
So I tested it in DD and I got a reading of 11.47A ( I’m suprised it didn’t blow the fuse in the dmm)
And 2.74A through the driver so I’m sure it’s my dmm that’s to blame
I love the pt54 it’s built like a tank and it comes with a pretty massive heatsink

Sounds like you tested the PD cell, and that's why the emitter blew, can't handle over 11A even with a good copper heat sink.

When you were first asking, the cell you were using is...I think...rated at just over 4A. That one should'nt have hurt the Cree emitter. The PD is a different story.

That test was with the Sanyo red cell
They seem to be great battery pack pulls

Yes they are, I am using them myself. I had my MT-G2 in the Solarforce M8 running direct drive. With 2 18650's the Sanyo FJ cell allowed 7.51A, Samsung 20R allowed 12.18A. I could run the M8 with a McClicky switch using the Sanyo's, was scared to attempt it with the 20R cells. lol Now it has a driver in it and is pulling 3.74A through the Sanyo's with 2 extra chips on a Qlite.

Hope you find the problem! I use Qlite's all the time, probably put in over 30 of em. Have 10 sitting here waiting their turn. ;)

I tend to approach it like this… a fully charged 18650 DD to an XML = potentially unsafe current levels.
How unsafe is arguable and there’s too many variables involved to really work out exactly what the max current will be and for how long before the cells sag or at what current that particular emitter will go pop.

So in general I think it’s best to just be cautious with any DD test especially if you want/need the LED to still be functioning afterwards.

If testing direct drive to ensure operability, I typically use a 14500 or 18350 cell.

Lesson well learned
I’m gonna have to send some business to RMM here soon

Yes those would certainly be safer, or use a partially depleted 18650 at around or below 3.7v resting voltage.
Then you can be sure there’s less chance of a dangerous peak current.

Well I fried an emitter tonight too :) I have (or had...well I guess I do still technically "have" it :) ) a cheap XM-L2 on a 16mm aluminum star that I've been using to test drivers, etc. for functionality after I make changes before I either send them off or put them into one of my own lights. I got everything setup like I always do, with the multimeter measuring LED current instead of input current. This particular driver had 6 extra 7135s stacked on it, which should give a bit over 5 amps if everything is working correctly. I hooked up the driver with a freshly charged 20R.... I went through the modes, low...medium...high...looked over and saw over 5 amps on the meter! Looked back and the LED was smoking something fierce. Good news is that the driver is fine! Still puts out around 5.10 amps to the emitter. This time I went with a copper star instead lol. I wasn't thinking about that... I had only ever run this LED/star combo up to around 3.7 amps before.

Life's still good and I was able to have a good chuckle about it. I've done much worse before. :)

Hehe yep I’ve had a few smoking test emitters myself. Though usually looks worse than it is. I bet it’s like the gunk and oil on the dome that vaporizes rather than anything truly bad actually happening. Never left the emitter on long enough to find out though :stuck_out_tongue:

So I always assumed that my stock dmm leads were off a bit, but they’re thick so I assumed they weren’t too bad. Looking a bit closer they’re 22 awg! I’m guessing they just have thick insulation on the wires, because the 22 awg I received from IOS is a fraction of the thickness.

Where would I go to find some decent, flexible wire for measuring current with a DMM?

12AWG silicone wire and some 4mm banana plugs.

I got some Tenergy Silicon Insulated 12Ga that is amazingly flexible, like a rope. I got gold plated banana plugs for each end to go in the DMM, works like a charm.

Can’t remember where I got em though, and can’t find the emails on em.