With regard to Herb's concern about the lack of a battery management system (BMS), I suspect that, as an electrical engineer, Josh (the builder) has it all figured out, but not in a way that's easy to understand.
2005 E350 Super Duty Ext Wheelchair Van
2002 Itasca 35U Motorhome
That ambo has a serious electrical system, but also has some serious electrical loads.
Not sure I like that the Tesla cells don't have a battery protection system, but Tesla must be doing something right to manage the cells.
Tesla (and Josh) definitely have a BMS. I think they just meant that the modules don't have a BMS physically integrated into them. All it really takes is the ability to measure the voltage of each parallel group and some key temperatures (and of course all the software/algorithms to make sense of the data). Maybe some balancing resistors.