I am already using mux for single battey measurement till 600 plus battery voltages. I divide the voltage to a comfirtable level and then measure. But in this case,

1. If I use a single tap from a joint, then I will have to bring the voltage down to less than the full scale of my ADC. This essentially means that, each channel requires calibration, and also that I must know the position of each tap and the voltages below it.

2. If I use differential input ADC, then I will need 2 pins per measurement. Moreover, I will still have to scale the voltage down since for differential ADC without input isolation, there is an upper limit.

If I can afford to draw 6-8 mA per cell, Can't I go for Opto? This way, can connect any cell to any input. I don't need to know the cell voltages or the order. I can also scale up the configuration for say, 180 volts.

Regards, Raj