so this is related to my other question if anyone wonders. I’m building out a EV battery pack to boost charge a vehicle in real time during heavy duty cycles. The vehicle currently has no external charge capability. It runs on internal battery pack with peak voltage at 266v DC and can go as low as about 35% of that around 100v DC (it’s not linear it seems).
I have built a few prototype battery packs capable of the 260-270v DC. The challenge is cell balancing and finding a BMS capable of doing the job in different configurations. Tesla uses 24v packs and then connects them together (serial/parallel?). I have a few thousand cells currently to work with.
The largest BMS units I can find get very expensive if going to say 72s configurations. At 14s they aren’t too expensive but then how to get up to the 260-270vDC.
I’d like to get some perspectives and would definitely like to hear of anyone who has conquered this for similar EV, BikeEV, MotoEV projects. Obviously the parallel aspects of each bank would increase total KW. But how many ’s’ in each bank is my challenge. The flip side is once the pack is designed it has to be able to be charged from a J1772 charger too.
The basic question is: What is the most economical configuration of Ns cells to get both a reliable BMS and up to the 260-270v DC?