Yea 4 amps should be okay but it may kill the LED after time because of excess heat. Generally any thing over the stock current amount Cree states is high which is 3amps with a XML2. Up to 3amps should be okay for a XML2 but a little over won’t matter.
You are right, probably I am to cautious. But I would not go over 3 amps.
I’ll use one for awhile to make sure all is okay. I’ll just state to only use with up to a 10A battery for 3.7A. This current would be less with the tail switch in place.
I’m currently charging a Panasonic NCR18650B with pcb to see what current it runs at.
I could also state to only use High for 1-2 min
I purchased 40 XML2’s 3 years ago so am wanting to sell off to get some $ back
This Convoy ramping driver is very cool though with excellent regulation
Its hard to say the article is old and the XML2 has changed production process which could change the way the LED acts. Older XML2s use to able to do up to like 8+amps now they burn out at much less current.
If you try, The LED won’t die straight away it will heat up and go blue and you will be able to turn it of before you damage the LED.
I appreciate the replies.
I think I’ll just use the 2.8A biscotti driver to play it safe for selling.
If the heat is too much would the output decrease as a sign? I have a lumen tube so I could monitor it. Since each LED varies I think maybe I’ll just use the biscotti driver. This new driver was a few $ cheaper so was hoping I could of used it.
Might be cheaper to buy drivers from Fasttech if you don’t min the standard 3 mode setup? These are the 3/5 mode drivers. Last ones i got where Convoy branded.
https://www.aliexpress.com/item/4000004827705.html?spm=a2g0o.productlist.0.0.3ec1435cNnM0P7&algo_pvid=4f1a5189-884d-4b6c-9f6d-135da0ab0614&algo_expid=4f1a5189-884d-4b6c-9f6d-135da0ab0614-54&btsid=86b4956a-868e-425d-8793-2ca21c75c758&ws_ab_test=searchweb0_0,searchweb201602_1,searchweb201603_53
When i tested my LEDs i direct drive them and they went blue after only a few seconds like maybe 10 seconds max. The XML2 might be able to handle a little more current compared to the XPL because it uses the larger footprint 5050 vs 3535 so that will more heat through. If it over heats to much you will lose output.
The old xlm2s were pretty robust, but the more recent ones seem to burn out much faster.
Grab some ∅16mm 5050 DTP boards and reflow your leds:
Warning: the ∅20mm 3535 
board sold in the above ad is not DTP, or at least it wasn't many months ago. Thermoelectric separated ∅20mm copper boards here.
Frankly, the light output between 3A and 4A would be so little as to be almost unnoticeable. Heat, though, not so much.
Already, given the downward-pointing parabola of output vs current, it’s already on the flattening-out part of the curve and could be very well be headed on the downward slope. So, 30% more current for maybe 5–10 more light?
This is so true, i actually downgraded several S2+ lights because of this exact reason.
Now running safe at 2,8A max happily :sunglasses:
And even at that, if you let it tailstand even 5-10min or so (ask me how I know), it’ll get too hot to even turn it off, let alone grab it.
It was like grabbing a curling-iron by the wrong end, that it fell to the ground, still on. Had to use a shirt as an “oven mitt” to just grab it long enough to click it off, and even then, had to let it air-cool a loooooooong time before I could pick it up.
@PiercingTheDarkness, Simon has been using DTP MCPCBs for a long while.
Just use them normally, and don’t exceed 3A on them.
Okay, 3A limit it is or I’ll have a go reflowing.
Cheers
No questions asked. I know how it feels, they can become burning hot, i have lended some of my lights when someone asked for a light, and exact the same thing happened.
Now i try only to hand over lights which are safe for persons not knowing the power of Li-ion operated lights. (a.k.a. noob lights)
Dumb question…
Why is running at 4 amps a problem? Is it just because it’s an aluminum board? There’s plenty of FET-driven C8 lights that work perfectly fine at probably 4A-5A (mostly using XPL, though). I presume they’re likely using copper head sinks. Do all of them? And, are they all safe at the higher amps? I haven’t noticed any issue, myself, for stock lights.
The difference in output between Convoy’s 2.8 amp driver, and a FET driver, is very noticeable (about 50% brighter by my measurements). Yes, the FET light gets hot quicker and eats up the battery faster, but it would be a shame to limit the current to 2 or 3 amps if it’s safe to go higher.
The thing is, since you are planning to sell these lights, we are just giving the advice not to run them on very high current, just because of safety reasons.
Djozz his test shows the light with a standard 2,8A driver already hits 90 °C, which is already sky high.
if you are planning on running 4~5A, these lights will even exceed 90°C, which is just not smart because of safety reasons (burning wounds)
My next answer would be a very unpopular opinion in BLF…
Running any LED beyond manufacturer’s max rating is bad for LED lifetime. Even if you can make the LED base temperature cool.
The reason manufacturer use conservative max current limit is the thermal path bottleneck at the LED substrate level. There’s thermal build up in the die. This heat will degrade the light produced by the die overtime. I tested many LEDs and the result always the same: after overdriving beyond max rated current the voltage and the output permanently reduced. And this doesn’t take many hours to happen, only few seconds. Permanent output loss is very prominent past 1,5x max rated current. High CRI and warmer CCT suffer more than low CRI cooler CCT due to thicker phosphor layer (hotter die).
[Clemence]
I’m surprised you say it’s only a few seconds (or even hours) at high current before LED damage is noticed.
I have plenty of FET-driven lights, that generally max out at somewhere around 5A per XPL with a high-drain cell. With throwers (like a C8), I exclusively use them on max. Even smaller lights I do that with, at least until they get too hot to hold (which I admit isn’t that long). They’ve had many hours at full output, and I don’t see any noticeable drop in output.
I totally understand that over-driving will decrease the expected usable lifespan of the LED. But, my assumption was that it would drop from 50,000 hours to something like 10,000. Or even if it was only 1,000 hours, that would likely be more than I’d ever use.
But just a few hours? Or seconds?!? I’m not seeing that.