Well a few thoughts. I would just use standard protected Li-Ions. I won't pay the premium for AWs, I'd rather have 2 sets of TrustFires for the same (or less) money. With stacked cells one will always drain faster. Folks often talk about marking and keeping the cells in pairs, I also suggest that the positions be flipped after each charge. You are attempting to 'age' the cells equally this way. Why protected? here's an example. I'm currently running a pair of TF14500 flames in a VV mod made with a $4 Chinese assembly. Running a 1.6Ω eGo DC @ ~4.3V. It just stopped. The first cell (at the negative end) is at 2.93V, the top cell is at 3.22V. This is not unusual, it's just the way it is. Depending on the regulator and output voltage you can end up tripping the low voltage cut-off on the bottom cell. Continuously tripping the protection circuit is not a good thing, but dragging unprotected cells even lower is worse. An IMR could be dragged below 2.5V easily.
mine arrived earlier in the week, connected one up after 10 minutes of head scratching, haven't done a schematic yet, odd device .. my power supply shunts between CC and CV continuosly. it did shut off at a little over 4.2v per cell .. cells where about 4v to start with but until i put a charge into them there was nothing on the output.
Schematic is in this datasheet.... http://datasheet.sii-ic.com/en/battery_protection/S8232_E.pdf Had a bit of a play with it. Was able to tickle it on/off using overcurrent mode but too much trouble to pwm it for a VV mod. Only good thing was it made me take a closer look at the dual mosfets in tssop package. I'll be using these in the next version of the VP pcb.
ah, the mystery 3rd chip, hadn't tracked it down yet, due to lack of any other voltage reference stuff on the board I had come to the conclusion it was dedicated. yes, looks a bit of a pain to find good signal levels to play with due to the sort of split supply scheme they are using.
