BQ29209: Series Connection for 4 cell

Hi Greg,
The bq29209 supports only 2 cells and no communication. If you connect 2 of them to 4 cells, a part would signal an OV fault if it occurred, but an external circuit would be needed to combine the output. One part would balance between cells 1 & 2, the other part between cells 3 & 4. It would not balance between the 2 groups.
If you add a third part it could balance between cells 2 & 3, the whole pack should become balanced. You don't need the OV output from this part since the cells are covered by the other 2. If you are controlling balancing you will need some level translation to control the /CB_EN pins of the upper devices.