Hello everyone, I have stated before that I have built many simple EVs in the early days. Mostly AGM batteries and early LIPO packs with a ceiling of 156VDC, those are always pretty simple being AGM and low count series LIPO. I am doing a personal vehicle project and want a larger than normal module but, I do not want to fall into the trap of pretending to know more than I actually do and doing something expensive, self-defeating, and dangerous. I have been researching but cannot pinpoint where the balance point is in a series/parallel aspect. So, I am hoping someone out there can give me constructive input. I am looking at constructing a battery module rated at 400 volts utilizing Headway 16Ah 40160cells. I would love to stack (3) 400VDC+/- in parallel, but that would require 125 cells in series and I am thinking that is not a good number. Are 125 cells in series a feasible number? I mean that's a lot of cells in series. A better way to do this would be? and how about this many cells in series for a BMS? And any ideas on a good BMS through your experience?