Wow. I'm surprised that it is even working for 2 minutes. I have a few very flat 17mm buck drivers that I got to try out, but they're only around 1.3-1.5A and have stupid modes (strobe-sos).
Do you mean the combination of XP-E2 + zener-modded Nanjg 105C + 2*18650?
Luckily my friend just used the modded Xsearcher for fun and has never operated it for long-continuous time. I have disassembled the pill assembly already and now I am going to put in a new Nanjg 105C with stacked chips and running a dedomed XP-G2. This way my friend is always going to run it with a single 18650 only.
Yes that's what I mean. Those 7135s have to be generating a ton of heat.
In that case why not go DD?
I have thought about that, but I have not learned enough yet to build any of these BLF drivers by myself.
Yeah this is better apparently, but is this FET similar to comfychair’s one which is capable of high current (low internal resistance)?
And I don’t even have a SOIC8 clip yet so… Anyway I have already added one SOIC8 clip into my cart in FT and ready to push myself to learn it later lol.
Sorry to bump this thread, but i was wondering, if i can use this driver to drive an MT-G2 using a single cell or to be precise a 3PS1, i still don’t understand how this could happen if this is a buck driver and MT-G2 needs 6V.
I’m planning to mod a Courui D01, oh well i could also buy a 6x 16340 IMR, but I’m just afraid of all those batt in series.
Since it’s mentioned in the IOS page it can drive MT-G2 or 2 led in series…Can someone shed some light on how this could happen
It can't drive an MT-G2 from a single cell. For that, you would need a boost converter (one in 17mm with any sort of significant current output doesn't currently exist).
You can drive an MT-G2 with this driver, as long as you have 2S or 3S cells on the input. The MT-G2 has a forward voltage of around 6.1V-6.2V at 2.4A, so even with 2S cells you have some pretty good voltage overhead.
I will go ahead and chime in on this since quite recently I have had a fair deal of experience with this driver.
The short answer is NO you cannot drive an MT-G2 with this board and only 3.7V (one cells).
Typically using 2 cells would have worked. I have been using it to power XHP-50s on two cells with an added sense resistor at 3.7A and it worked well.
However I will say this. The newest batch of these I ordered from IOS have some issues. The old version could drive an emitter at an almost linear rate. IE you would get full power to a 6 V emitter off 2 cells. This new batch it would drive the emitter at only around 600ma :( Unless you use higher voltage. It would take at least 3 cells in series to get the full amperage to the emitter now.
FOR SURE the inductor on the new batch is smaller, and I suspect other components may be changed as well causing this huge loss of performance.
I have sent one of each to someone with FAR more knowledge of this stuff than myself to do some testing, to find out which components will need to be replaced in order to get them working like they were before.
Just saying: This driver powers an MT-G2 at an ok level. Light is a Convoy C8 with a widened, smooth reflector, aluminium pill and 18650 extension tube.
.
To my eyes, output is pretty much the same as a 3.0A driven T6,XML2. High current draw with two freshly recharged laptop pulls is 1.44A, med 540mA and low 50mA. Should’t 2.4A to the MTG2 result in a higher output than an XML at 3A?
.
With two partially depleted LiFePO4 cells on high mode, there was some weird flickering/dimming that looked like a bad connection but didn’t respond to knocking the light and disappeared in med and low modes. Current draw on high was 1.70A.
.
With two samsung 30A (or 30Bs) charged to 4.30V, current draw on high was 1.55A. I thought this was weird since the driver is supposed to be buck and as voltage goes up, current draw was supposed to reduce…
.
Either way, with the two laptop pulls in the light, I added on a third cell to see what happens. (driver is supposed to handle up to 16V.) BRIGHT, 2.45A Yay!! oops, battery slipped, reset, nothing… battery didn’t slip, something died. I assume the driver died and not MTG2 but it was not the usual stinky, dead IC smell so can’t be sure yet. ;/ Will confirm this evening when I get home.
EDIT: after removing the driver, i got the familiar, burnt electronics, stinky smell. using a 40x magnifier, it looked like the sense resistor alone was burnt. I didn’t have anything similar so swapped in a R015 resistor from a laptop pack… Nothing happened ;( I can’t see anything else that is burn’t.
.
Zener modded a Qlite and used that as the driver instead. 
(I’m surprised to see that moonlight with the MT-G2 is the same brightness as an XML2… )
I just finished reading this thread because I just bought an LD-4b from RMM. I want to use it in my Supfire L3. My plan is to put it on top of the existing, now stripped driver. Looks like I should get ~ 2.4a to the XM-L2 T6 emitter using 2 26650 KK's. Then maybe change the sense resistor to something like .08 - .07 to get a little more output. Maybe ~4a. Someone please tell me this going to work. Didn't see anything in the part description saying anything about how many or what kind of emitters to use. So I assumed it would work with one XML.
It will work with a single XM-L, but if you look through this thread you'll see that the 4A modifications ended with failure. You have a better chance of beefing up that stock L3 driver than one of these, IMO.
Ok, what driver on your site do you recommend? I do not want DD though. The stock driver board has been stripped. This kind of sucks because you just shipped me my ld-4b today. Its ok though, I'll use it for something else. You live and you learn..
I didn't give the stock Supfire's L3's driver a chance because I didn't see any large fets on the board. They are/were all those tiny 5-6 legged thingies, I think we talked about this before? I forget.
If you want to be able to use two cells, then I'd use the 5A buck driver, then ditch the contact board and thermally pot the driver onto the existing PCB. That one is at least designed to do 5A. You can turn it down a bit to ~4A by removing a few of the sense resistors.
If you are piggybacking any buck driver, you need to make sure that there is a decent thermal path to the flashlight's body. You can't just air wire one on top of another driver and expect it to live for more than a few minutes. We get away with that with the FET drivers because the heat dissipated in those is very very small, but in a high-power buck driver the losses are significantly higher and they will overheat. Most of the small 4A+ buck drivers are already running on the ragged edge with a good thermal connection.
RMM, what in particular heats up in a high power buck driver?
By any chance would you be able to post a side by side pic of the old and new versions?
In general I think the buck ic, the inductor, the sense resistor(s), and the (flyback?) diode are the main victims.
Thanks for that about to blow up a few things
I replaced the stock R100 resistor on my LD-40 driver with two R120 resistors and I measured 2.45A at the tail (with two 18650) of my Uniquefire 1405. It works, but not satisfactorily. The mode changing becomes strange, that it requires a very fast tap on the switch to change the mode. Not only that, the light cannot be run on high for more than 2 minutes otherwise it will shut off by itself due to the overheating of the driver.
Short answer: Yes it is not encouraged to try bumping the current of this LD-40 driver.