Looking for cell voltage sensing on 6S LiION pack, using 3v3 MCU

[Odd]

Right now, my project uses LM321 , which is driven of the battery voltage, to return the difference to the microcontroller: (see attachment)
This requires more expensive opamp, and exposes the opamp to direct battery voltage/spikes/reverse polarity and so on.

Please suggest a design where the opamp can work on much lower voltage - even 3v3 ?, and (preferably), return about the same voltage to represent each cell (up to) 4.4v  (which should be about 3v2 for a 3v3 MCU)
Maybe somebody already has the design, or have seen it somewhere?
Thank you

[BILLPOD]

Good Morning Odd, It would help if your design utilized one of these connectors to maintain a charge balance: https://www.amazon.com/RC-Battery-Balance-Extension-Charger/dp/B073ZG6QBZ