Seeking advice for how to stack resistors - FX-30 driver mod in Convoy L6

Hi all,
I snagged one of Simon’s surprisingly reasonably-priced FX-30 drivers , and since I have this as a backup in case of failure, I’m interested in trying a mod to bump up the amperage a bit on my L6. I remember reading that a few people have stacked another resistor (~R140) on top of the existing resistors on this FX-30 driver, in order to slightly increase total output. I’ve done a little bit of soldering and a few driver or emitter swaps, but I’ve never done a mod like this involving a single component or resistor. Before I start soldering, I wanted to double check that I’m putting the new resistor in exactly the right spot. Does my added R120 (drawn into the picture below) look correct, stacked approximately centered on top of the existing R082 resistors? Green color = intended solder placement.
Any other advice before I start?
Alternatively, if anyone has a picture or video of a similar mod they’ve completed, that would be very helpful!

TIA,
Andy

That would be correct, takes less time than flipping the driver out of the light.

I used the R140 because I have a lot of drivers from the Lucky Sun D80 that each have 2 of those on em so they were plentiful and close to hand. Turns out it makes some 6.3A with the R140, for ~4600 lumens, so that was good enough for me. I also used a top bin XHP-70 on a 26mm MaxToch copper mcpcb with the emitter shelf cut wider to accept the larger mcpcb. So my results may or may not be obtainable without doing all of the above.

I find the light performs well at this level, has decent run time and manages the heat pretty well, so it was a good balance.

Thanks very much! I appreciate your quick and thorough response.

Sounds like the R120 resistor might push it a little too hard, especially without the further mods you mentioned. Would you agree the R140 would be a safer choice to start with?

Sorry, remembered the MaxToch mcpcb size incorrectly, it’s a 31mm.

The R120 is close enough it will probably be at or just under 7A, should be fine. I’ve run an XHP-70 at around 12A on an FET driver for some 6400 lumens in a larger light so it’s got some head room there…

Thanks! :beer:

I have R120 in mine, with Efest 4200mAh (green) my DMM reads ~7A at the tail with full batteries, it drops really fast tho so after 7-10 min runtime you will probably be in the stock range 5A or so.

Well this is a first! Who are you, and what did you do with DBCustom??

Seriously, this is great thread for resistor mod, I have been hesitant to do one of these on my S70 as I had no resistors I thought. I do have a few old D80 drivers, so thanks Dale!

Has anyone done a stock S70 resistor mod, or just bypasses?

Well, contrary to popular opinion, I do, at times, have a wee bit of sense. :wink:

Yes, I modded both the S70 and L6 yesterday actually. Stacked a R100 on both of them.

The wattage jumped from ~35-38 watts stock to around 55-60 watts on both drivers. (around 7 amps if you want to talk that way, but it will vary depending on battery voltage)

The S70 is a bit larger and handles the heat a bit better but the L6 has a WAY better beam and tint. Lumens are basically the same as well.

I might try a R120 if I had one laying around but I am not upset with the R100.

I, on the other hand, found the S70 to be very inefficient when pushed hard. I got mine up over 9A and had to step it back down twice… on the lightbox it showed the lumens falling very fast within the first 20-30 seconds and continuing at such a rate as to make it totally not worth doing. Sure, it was bright initially, but if it fell all the way down to stock within 40 seconds or so then what was gained?

I was disappointed with the S70 in that regard and ended up giving it to my Brother-in-law. While I had the L6 here I’d never use the S70, he didn’t have anything remotely like it so for him the S70 is awesome! lol

At those kinds of power levels it is not surprising, you would be on the trailing end of the curve and lumens should actually be dropping as you add more power at that point according to this: https://farm8.staticflickr.com/7567/16071892179_7d89411e10_o.jpg

Using them side by side, both in the 55-60 watt range the S70 does take noticeably longer to heat up. Makes sense as the head weighs 25% more. To the naked eye the tint plays a larger role then lumens.

I just ran a test on them actually to see what the difference is. At basically the same power level, on the same keeppower 4200mah batteries fully charged to 4.20v. I turned them both on turbo (and kept resetting the S70) and let them run for a bit over 7 minutes. They started out within ~150 lumens of each other and dropped about 100-150 in the first minute or so.

I checked the temp with an IR gun and they both rose at about the same rate except the L6 was always about 5-10f hotter then the S70.

After about 5 minutes the L6 was around 115f and the S70 was around 105f and the temps had pretty much leveled out. by 7 min and change the L6 was at 120f and the S70 112f.

I then retested light outout and they were basically the same again, interestingly they were closer after the test, about 100 lumens difference. Total lumen loss was around 300-350.

When I pulled the batteries both sets were at 4.01-4.03V, so the lights really did use almost the exact same amount of power, so the test is about as fair as it can get.

One thing I did notice is that to my hand the S70 “felt hotter” in some ways because of the smooth ano finish. I guess it transfers heat better or something. The Ir gun tells the real story.

They are both great lights, honestly they are quite hard to compare because they are so dang close.

I did run a little experiment the other day after modding them and showed them to some people to see what they thought based on looks alone.

It was 100% unanimous, The L6 won the looks contest hands down. They all said the S70 looked cheaper and felt “low end” due to the slick ano.

For a performance aspect they all preferred the L6 beam as well, they all pointed out the donut hole in the S70 as odd. Most of them also preferred the L6 3a tint as well when compared side by side.

To the layman the only feature that the S70 had over the L6 was the lighted switch, although once I explained that the L6 blinks when it’s battery is low they said that was ok as well.

The smoother glossy anodization on the S70 would skew the IR gun results.

Not trying to negate your findings, but I do know the IR gun reads a matte black finish more accurately.

A lot of people seem to like the illuminated side switch of the S70. I find a glowing switch to be a nuisance in use and for a tactical situation, downright dangerous to the user. Simple enough, usually, to keep the thumb resting on top of the button thereby eliminating the source of glow but still…

Yeah, I have noticed that they don’t read glossy surfaces as well but if you take a reading down in the fins they are usually pretty good.

Also if I firmly gripped both of them to get equal contact you could easily feel the L6 was hotter, it was only under “light touch” that the S70 felt the same.

Like I said, they are really so close it doesn’t matter from a performance aspect. You will not find anything to definitively say that one of better then the other. It all comes down to preference and looks in this case.

I like the L6 better myself but the S70 makes a nice “beater light”. Honestly I think it will look better once it has been worn in some.

Another “plus” on the Convoy L6 is the possibility to use a single cell tube with 2 of the new 26350 cells. Makes for a very compact but still quite potent powerhouse! :smiley: (doubtful anyone would carry it in a pocket though. :wink: )

Yep, a single cell tube does make for an interesting sized light. I say interesting because I am not totally sure what I would do with it over the dual cell tube but I am sure someone would have a use for it.

what will be advantage/disadvatage of using r120 vs r100 resistor?

Less heat, more run time with the R120. (R100 will be less resistance, more amperage, somewhat more lumens)

thank you db

Does anyone know if adding a resistor effects the other brightness levels or just the highest level?

Only turbo mode, other modes are not affected.