I think OP wants to measure up to 30 LiPo cells in a stack (~126volt).
Then voltage dividers on each tap are not practical anymore, because of the uneven drain on each cell.
There are special (= expensive) chips to do this, and they seem to be made of unobtainium.
I opted for "flying cap" and relays.
DIY friendly, cheap, no drain on the cells, full isolation, and only one A/D to measure it all (no differences to calibrate).
Stack voltage can be as high as the stand-off voltage of the relay contacts allow.
The 24-cell system I made scans all 24 cells in about half a second.
Only downside so far is the prrrrrrrrrrt noise of the relays every time the cells are sampled.
How does it work:
1) Go to your car with a capacitor, and connect it across the battery terminals.
2) Walk back to your workshop, and measure voltage on the cap with a DMM.
3) Go to the car again, and connect the cap across the battery terminals.
4) Leave it there, connected, untill you want to measure again.
If you do this at regular intervals, then you know the state of the battery.
You only have used battery power once, when you charged the cap for the first time.