O'K, I see, and you choose 2.45V per cell?
Using high side current sensor, you 'd have only 0.1V drop across a resistor, plus after voltage divider it diminishes to about 1/3, and after all 30 mV at analog inputs difference 'd be present. That accounted to 6 "tick" of the ADC w/o voltage amplifier. I think it's better to transfer current sensing resistor down into source path of the mosfet. As 0.1V voltage loss 'd not make much difference, same time current control loop 'd looks locked and more accurate.