Recently I bought cheap a lot of CASIO DT-9723LI battery packs.
Every pack consists of 2 Sony 6th-gen Li-ion 18650 cells and its own 2s BMS. Here the question arises: Can I connect this packs parallel and series simultaneously?
My desired pack must be 6s (so 3 Casio battery packs in series) and 9p (9 Casio battery packs in parallel). I know that I could take out the cells and build a new pack with its own new 6s BMS, but that is a lot of work. On the "old" BMS PCB (from the Casio battery packs) I found two TPCS8208 Field Effect Transistor and one S8232A Battery Protection IC. Maybe it will help.