Have wired up the components for the BMS. The image shows a couple of relays on the right which were not in the image further up. These are the relays for charge disconnect and load disconnect.
I will not use those, they are not latching, well at least not mechanically. I will use latching relays to avoid permanent power to the relay to avoid heat build up and power loss. The ones in the pic are latching but electronically. The processor stack has another shield on top. It is a IO extender because with this application I need more analog inputs than the Arduino can provide. I read the actual charge current when cell balancing and that requires 4 more inputs and the Arduino has only 6, of which 4 area already used to read the cell voltages.
The only component missing now is the display. If I don’t do the active balancing the whole unit will be rather trivial. I will do one too. the software is just a subset and will use it eventually for the 2 Lithiums which I will use in the truck.

I will complete the software in the next couple of days without the display. When I have the display and finished everything I will hook it up to one of my 9KW banks, the pack with the one lower cell for test.