I have 8 battery cells (3.2v-3.7v ea) that are in series to give me ~28v. I would like to monitor the voltage of each cell. Any suggestions on how to do this and not create a ground loop? I went down the path of using an octo, and it sorta works, but the values aren't linear making it difficult to calibrate. It looks like a lot of project put a small PIC on each cell and have it report back to a master via octo protected communication. I'm trying to avoid having to do that since I'm only looking to monitor 8 cells.