5 72v battery packs of 18650s in a Nissan leaf?

Is this doable? Like three battery packs with separate bms units that are all 72v battery packs with a bunch of 18650 cells in a box in the back of my Nissan, run the power connection for the battery and vehicle input and everything here and use a Arduino to turn on and off 360v relays or whatever so I can use only one at a time and switch off? Or I guess run parallel but I'm not too sure If that would be a good idea. Also need to figure out how to disable Regen braking because i have no idea if that'll be a good idea with the series of 5 packs.