I own and am generally quite happy with a 2013 plug in Prius. Unfortunately I can rarely make a trip which doesn't use gas. I sure would like 2x or 3x the EV range. I have looked inside the "battery" and convinced myself that replacing the cell modules with arrays of 18650 cells retaining the stock BMS etc. can result in significant range increase. Using for example the LG INR18650MJ1 which is rated at 3.3AH and 3C continuous discharge it would need 15P56s to support the 150 amp fuse current. The stock battery is composed of 4 cell modules, each is 14s with cooling air duct-ed between modules, I'd copy this general layout, including similar cooling. I've done a quick sketch in Sketchup using 18p blocks and it fits inside the stock enclosure, with lots of space for cooling and mounting. Has anyone done it?