Since this is my very first 'essential' post here, I'll shortly indtroduce myself...
I've been AF (Anonymous Flashoholic) since the middle 2017. At least this is the date I've started to read BLF and even worse - started to buy ... THEM !
Yes..., I know I should not, but... I buy THEM because they are cheap, sexy and ... available . Someone, please help me to stop this...
Looks like, I'm especially in love with Convoys S2+ (well... basically it means - whenever price drops below 9$ I buy them, sometimes I manage not to do so). For this price man can buy only 'basic' 6x7135 XML2 Grays... and it's ok for an addict like myself (guilty me, once a month you have to take your dope)
Of course, last year it happened to buy some other stuff as well (2 Convoy's C8s and 1 C8 from Sofirn when they droped below 15$, and 2 SP33's lately on Christmas for the less then 20$ each) but you know what they say - the first love is the biggest one and for forever...
OK, now to the point - this about my first mod.
Let's call it "Quick and dirty 2S (2x18650) mod to 2S+ "
The background...
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1) To many 'grey' S2+ on my shelf. To many to take everyone and each of them for a walk from time to time
2) Plenty of 18650's (many of them not so modern high drain models)
3) The curiosity - what the XHP family (or the other high output 6v Leds) can do inside my little beloved one ...
The obstacles...
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1) Mainly there is one.
Why the heck they don't produce and sell extension tubes in a most common size (18650) for a most common flashlight (S2+) on the planet ?
You can easilly find them for L4's, C8's and many others but not for S2's !!!
The decision...
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One of my sweethearts must die... to give the birth to something bigger...
The result...
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Remove everything form inside the head of S2+ and cut it exactly in half (I did it with a dremel tool)
Now, you have a muff wich will hold and connect two original body tubes of S2+'s. The thread must be milled out 3-4mm deep from one side of new muff (one where was a cut made) for the best matching with the original tubes. Do a final polish to the sharp edge with some sand paper, and we are done with hard metal tooling...
About the LED...
I've choosen XHP50 (it has good output, it is efficient in low current, it has high Vf value which should ease a load on my 7135's and it was ridiculously cheep to get.
About the driver...
I've decided to keep the one what I have had form inside a donor light (costless solution).
I had no suitable electronical components for a 'Zaner mod' modification, so in my case the original Convoy's 6x7135 dirver board was used as a simple 'one mode' linear 2.1A current regulator.
To make it work:
1) Remove D1 from original driver board (the same element which you remove to place 200Ohm resistor in classic Zener Mod) - this will disconnect excessive (+8V) power voltage from the MCU (we may need it in the future...)
2) Connect VDD leg of any AMC7135 (one of them is enough because all AMC's are in parallel) to +Vin - this will open a full throttle of all 7135's (6x350mA)
For my current needs it suits good enough to have one "high" mode only. Latter (e.g.when I get a proper Zener diode) I may consider to restore MCU functions for this driver.
Since basic Zener mod destroys the proper low battery protection then you may try to restore it by modifing the board (cut of the trace with the original R1/R2 voltage divider and build a new one which would be powered by +Vin). An example was given - e.g.look for "The IMR Enhanced Zener Mod to run the MT-G2".
So how does it looks like ?
Pros:
1) Twice as much 'floody' lumens comparing to original design (for 2.1A XHP50 gets 1560 lumens vs 800 lumens for XML2). You can really see the difference in the dark.
2) Does not need expensive high drain accus (like when you power up XHP from a single 18650 cell) or some fancy low capacity and high price 2x18350. It comfortably sucks 2.1A from every low cost 18650 I have in my drawer.
3) It gives similar running time to original S2+ with more light
4) It is still very convenient in every day use. It's size is just 43mm (1.7inch) more then C8. Fits well your pocket since it is as thick as an orignal design. And feels good in your hand.
5) It was planned to be "zero" cost mod. And in fact it is (almost). I had to "sacrifice" one of my Grey's (cut off the head) but it was worth it. I bought XHP50 on a 17mm copper mcb some months ago for 2.5$ on AliExp (4.5$ including delivery! minus 2$ coupon)
6) And it's still "my precious..." S2++
Cons:
1) Of course, it is not so cute and handy as a original S2+ beauty, but still close to my liking.
2) Get's a bit more heat in 'high' mode.
This should not be a big issue since the original design has some redundancy and is pretty safe with 8x7135 and XML2 pill (power used by XML2: 2.8Ax3.4V=9.5W plus power lost on 7135 regulators 2.8Ax(4.3V-3.4V)=2.5W makes 12W loss in total) and mine has 6x7135 and XHP50 LED (power used by XHP50: 2.1Ax6.3V=13W plus power lost on 7135 regulators 2.1Ax(8.4V-6.3V)=4.4W makes 17.4W loss in total).
Not a big difference (5W more), but the body of moded S2 is now longer so the heat dissipation should be also a little bit better.
This post has been written by a beginner (myself) and for beginners, so all experts and advanced users please be gentle or just skip it...
Cheers to all BLF flashoholics...