The manufacturer employed SK26A which is a 2A60V diode for this buck driver. I guess that the drive current is around 1A to 1.5A. You just replace the sense resisters to boost the current to 3A may not be possible. The ability of the inductor and the driving IC are also to take into consideration.
driver ic (A6213) is capable upto 2.5/5a depending on ic version used ) no idea about inductor.
Buck Switch Current Limit Threshold ( min - typ - max )
A6213 - 3.0min - 4.0typ - 5.0 A max
A6213-1 - 1.9min - 2.2typ - 2.5 A max (i guess i should go for 2.5a max)
i have only R180 resistor to experiment right now. will see how it goes. btw i was wondering if output current goes up/down linearly if resistor value is halved/doubled respectively ? or only way to find out is by experimenting ?
anyway thanks for helping me.
You definitely donāt want to take a big step like going half or double. I have only messed with sense resistors in linear and boost drivers, but not Buck. In just about all those instances slightly lowering the resistance saw a noticable increase in output.
This one driver had a 0.04 ohm sense total and put out 4.6A. Changing the value to 0.03 bumped up the current to 7A. So small resistor change equals big output change. Itās probably one of the reasons this driver uses two resistors in place of one bigger one. You canāt always get the exact value resistor that you need, so the manufacturer can use two different values combined to get just the right value.
Using one .360 and one .180 gets you .12 total. Thatās a pretty big jump from .18
Maybe get a few .300 and .250 to go along with the .180 you have.
A .360 and .300 will get you .16
Two .300 will get you .15 (same as .360 and .250)
A .300 and .250 will get you .14
Two .250 will get you .13
A .360 and .180 will get you .12
A .300 and .180 will get you .11
A .250 and .180 will get you .10
Yeah, that should work. Buy some R300 and R250 in the correct package size and you can get whatever value you need.
hmm, okay seems like doing that will not damage the driver either. will order some R300-R250s today. thanks.
Have you already seen new Convoyās boost driver? Looks like well designed driver.
https://www.aliexpress.com/item/4000046041955.html
- 22mm diameter
- 2.3A max. current
- MP3431 boost IC
- big-ass 1.5mH inductor
- large MLCC bank on the ouptut
MP3431 is very powerful boost controller:
- up to 16V output
- up to 40W to the load
- up to 13A input current (programmable)
- in theory should provide 5A output current for 6V XHP50.2
Link to IC:
https://www.monolithicpower.com/en/mp3431.html
Looks like promise to even higher perfrmance than H2-A or H1-C. Iāve ordered some quantity and it will land on my test bench soon.
Considering the driver comes stock with R360s, swapping them with R300s nets you a 20% current increase. Using R250s means 44% increase. Its an inversely proportional thing. With R220s the increase is 63.63%, and +80% with R200s. You may want to also swap the smaller schottky diodes in such a case, and even add some extra output capacitance. Ask the experts LoL.
Suffice to say, at your own risk. O:)
So if he wants to go from 1.5A to 2.5A he needs about 65% increase. When you say āwith R220sā you mean two in parallel which equals 0.11?
A .300 and a .180 would also work.
Hmm, just replacing one of the .360 with a .180 is pretty close at .12. That might work. Hopefully it wonāt burn up. Lol
well, it does seem like itās inversely proportional to that resistor. i found this pdf about the driver ic which is used. and it indicates same thing i guess same should apply for my driver too ? does this apply for all buck drivers ?
link to pdf
apart from those schottky diodes, anything else i need to change ? along with resistor ofc. hope it doesnāt burn, headlight costs 98$ lol
On my motorcycle, I just swapped in an aftermarket led bulb that gives me a stock cutoff pattern, but noticably brighter. Easy peasy. 
Wow that MP3431 datasheet shows 97% efficiency @1A which is around the current I need. Just need a driver with more evenly-spaced or configurable modes, and a ~3V cutoff voltage.
EDIT: Appears to be PWM not constant current :person_facepalming:
I thought that driver was 12v out only, not 6v.
Have you seen Loneoceans boost driver? He does not sell them, he just designed it and shows others how to assemble the parts.
What would prevent me of using ā12Vā constant-current mode driver with 6V LED? :question:
NarsilM - Neolithic Advanced Research Superior Intelligent Light Module
Yea, right.... 
From the source code: "the sword wielded by Isildur that cut the One Ring from Sauron's hand"
Let me see, I started working as a programmer in 1979, also bought the very first IBM PC for my own home use about in '82 or so. Also in 1981, started doing my first consulting gig at $17/hour - hit the big time!
I should add that over these 40 years or so, I've done a ton of firmware projects, most or all where the firmware had no name, least that I can recall, because basically, hardware such as fault tolerant server, graphics controller, terminal, typesetting system, treadmill, or any other device I've written firmware for gets only one functional version of firmware and is an inherent part of the product. So for example I might have built in a feature in the treadmill firmware to pause/resume, but that's a feature of the mill and listed as so.
In this BLF/flashlight kind of environment though, a name or way of identifying it is more important since there are many choices. We could have gone by the author but that has it's problems and is not conducive to the open source, open nature of the forum here. Also could have used some acronym that stands for something clever, but no one will really remember or care anyway, so Narsil or NarsilM is about as good as anything. I followed TK's lead here for using names like this, and Anduril, of course, is the natural successor to Narsil. In fact as I recall, TK asked me privately if it was ok to use that name, and assured her it's no problem at all.
Just a little history here....
Yes JasonWW, Loneoceanās driver is a tease but I donāt have that kind of time. Iāll just stick with the H1-A mod until MTN has their BST series back in stock.
I accidentally broke my old one marked 2R2 and now Iām getting a 3% efficiency drop (92% to 89%) @1.25A with the new one marked 1R5. Well that kinda sucks.
It does not bode well, I wonder what would happen on high when sense resistor modified at 4+A. 
Can you try replacing the inductor, to see if it restores the efficiency Nightsword? 
Stuff like this sort of takes away my appetite for, honestly.
I still have the old driver with 2R2 inductor, but I absolutely wonāt do anything that might damage the newly modified driver, because changing the resistor is a PITA. Let me know if thereās a sure way to replace the inductor. While at it, may as well go bigger than the 2R2.
Unsolder the current, solder the new/replacement one. This is easy. If you have some parts lying around, that is. I do, but guess I may be too far away. O:)
The solder joint near the resistors is risky for me. Iām going to skip this mod, use this H1-A as is for now, and then get a MTN BST driver when theyāre in stock.
Doh!!!