Like the Thrunite MCC-2, the Xtar MC1 Plus and the Liitokala Lii-100?
4.35V cells aren’t as high drain as the top imr’s so the extra voltage can be lost to sag. To my mind their best usage is in buck mode where the added voltage translates to lower initial current making the most efficient use of the power that voltage represents. Another use is in 16650 applications where the extra capacity then exceeds other chemistries in that size. For moderate drain use any of the better quality high capacity cells will be fine, exactly which one runs longer depends on how much time is spent in each mode but the difference will be small in any case. When looking at graphs it’s good to have an idea what the Vf is at your target current so you can see where it begins to drop out of regulation rather than simply looking at end points of the test. For DD drivers the discharge curve will indicate what kind of output to expect at different points. The voltage indicator in bistro can help with this if you bother to memorize the curves for discharge and led output(which I don’t).
I received my S2+ just a couple of weeks ago, yet the inner tube is rather narrow.
I just bought an S2+ two weeks ago, well four weeks ago if you count shipping.
The tube I.D. is: 19.09mm. My Nitecore batteries have an min. O.D. of: 18.40mm. The
wrap is somewhat lumpy so the max. O.D. is: 18.50mm. Regarding the narrow tube’s, I would just open up the I.D. on the tube, then anything will fit! (Provided that the wall thickness of tube
can handle stock removal without crashing through the threads.) 
I just started buying batteries and I have a Convoy S2+ and C8 coming in. How do you protect your unprotected batteries for a flash light? Do you just check with a voltmeter once in a while?? I’m a noob.
S2+ and C8 has built in low voltage protection. It will go in low mode and start blinking 2 times/sec if voltage drops to 2.9-3.1V.
That’s low voltage warning, it’s not actual protection.
But “3 Volts” LEDs have a minimum Vf above 2.5 Volts, so even without warning or protection the light will get very dim or will not give light at all before your battery is in danger.
Jerommel when the LED shuts down the MCU and 7135s will still draw on the battery, so if left alone long time with switch on it will damage an unprotected cell
True of course…
You can’t leave it ‘on’ without protection.
As of today, 24.02.2017, the stock Convoy S2+ has this behaviour.
In other words, it has a low voltage warning, but it does not have low voltage protection (a.k.a. low voltage cutoff). It is perfectly capable of draining an unprotected cell to the dregs (and destroying it) when left running unattended - for example, if accidentally switched on in a backpack.
Convoy do have a new firmware version (written by Toykeeper) which does have a low voltage cutoff, but the only stock light that comes with it at the moment is the clear-anodised Convoy C8.
It is possible to message Simon Mao through the Convoy AliExpress store and request the firmware upgrade on a Convoy S2+, but I haven’t done that myself, so I’m a bit fuzzy on the details.
I presume that Convoy will gradually roll out the new firmware on lights like the S2+ as they work through their old stock.
If you are in the U.S., you can buy the Sanyo NCR18650GA from Li-Ion wholesale for $6. very good test results, 3500 mah and 10 amps continuous makes a pretty sound battery. Capacity and amperage CAN BE achieved after all.
you can buy the programmer clip and USB board for around 4$
then you can program new firmware to all your driver for the same price than one new driver is on BG
There seems to be quite a bit of variation in S2+ internal diameter (even in the same batch). Single wrap protected GAs only fit in 3/4 of my S2+. I’m now using unprotected GAs.
Should i get button top or flat top 18650 for my concoy c8 and s2+?
There are springs at both ends so you use button top, raised top, and flat top.
I don’t have a C8, but my S2+ lights take button top and flat top cells equally well.
The way to tell is to look inside the battery tube. If there are springs at both ends, then both button tops and flat tops will work.
If there’s no spring at the head end, then you may be forced to use button tops only. This is often because the light has physical reverse polarity protection, which you’ll generally be able to see as a raised ring around the positive contact.
It’s easy to fall asleep while the lights are on, or have the light turn-on in your kit. I know, back off the tail cap when packing your lights.
When the led shuts down because of low voltage (when the voltage is below the Vf for a very small current), shouldn’t the led act like a resistor and pretty much stop the current? Is there a parallel path for current in the driver?
The MCU is in parallel with the LED. The 7135s are in series with the LED, but they also draw a small current via the MCU. Total current at that level is only a milliamp or two, but that’s still enough to kill an already-discharged cell within a few days.
I just bought 8 x S2+ SST20 7135x6 for Christmas gifts. I also bought the LED switch but wonder if they will override whatever LVP is built into these flashlights and destroy a non protected battery?