The resistor mod, trying to figure it out for my C8

I feel like all I do here is ask questions… But here’s another one…. :~
Sooner or later I might know enough to be able to start contributing more….

So this time… I’m trying to learn about the “resistor mod”.
I’ve been googling for the past hour and trying to find out more about it, but most of what I’m finding is going right over my head….
Are there any good, starter threads about it I’m missing?

I gather that it’s some way of raising the amperage, without changing the driver, but I haven’t been able to figure out exactly how to do it.

I have a Convoy C8 with an XML2…
As far as I know, it’s 2.8 amps stock. Can I even push that up any without needing to change anything else, or will I need something like a noctigon to take the extra heat?

The resistor mods discussed on here are primarily related to buck drivers using sense/limiting resistors to tell the buck controller how to regulate the current. (“buck” drivers are mainly used when the battery voltage is significantly higher than the voltage required by the LED).

In your situation, you’ve got a C8, which runs on one 18650 cell with one LED. It’s rather unlikely you’ve got a buck driver in there. Most likely it has some form of 7135-based current regulating driver. You can increase the current by adding/stacking on more 7135 chips. I learned how to do it by watching Old Lumens’ videos (and much practice):

If it's a Convoy C8 then you have a 7135 based driver. If it is 2.8A it likely has 8x350mA 7135 chips on it. To increase the output, you can add more 7135 chips (see posted video above).

You can go up to 3.4A-3.8A with the aluminum MCPCB. 4A+ and you're into dangerous territory. At over 3A you will gain some output by switching to a direct thermal path MCPCB.

anxiously awaiting my order of 350/380mA chips from you, should be here tomorrow!!! lol... Good info, thank you for sharing! Can you tell me how much is too much (what is a safe amp draw) with a xml2 on noctigon without any other heatsinking. I'm building a convoy m1, xml2-u3-1a, if that helps, looking for the maximum possible output.

With one of the newer XM-L2 U3 emitters you will have a hard time getting much over 5A due to the increased forward voltage, even with the best of cells, so there is very little point in stacking more than 4-6 extra chips on the driver. You won't overheat the emitter at 5A on a Noctigon.

Are AWG22 soft silicon cables are ok for 4-5 Ampere?

Awg22 are ok. Bigger wire is better but sometimes it is hard to get the reflector in place and these pieces are so short that it makes not much difference so you have to decide what is more practical.

The most resistance is in the springs, if you aim for high amps you have to bridge them with copper braid or a short piece of wire.
On some lights it’s also worth to check the switch for resistance.

Also it is important which batteries you use, these linear drivers dim very quickly on some batteries with a low voltage

All points have to be checked to give a reasonable success.

They’re fine. I even had a triple xpl running 9A through 22AWG.

Thank you Chazzy and Werner: I found only a list for thikcer cables before. Now I will order a pack of intl-outdoor (6m for $3,89 - this will be enough for years).

I tried like 3 times that 7135 chip stacking, its easy but always i got same issue - after some time ( like 10mins of continious work) the driver lose its modes- its not permanent- when it chills( the driver) the modes come back again