I think the latest li-ion cells, such as for Tesla Model 3, have energy density something like 4x the the OEM Prius traction battery cells (Google primearth np2 ). Now Samsung makes the 21700 40T cell which are capable of 35A continuous output. According to OEM cell manufacturer the cell output is 1350/7.2 = 187.5A, equivalent to 6 or more parallel li-ion cells. My own car, a Prius C, has total pack voltage of 20*7.2 = 144V, equivalent to 40 series li-ion cells, at nominal 3.6V/cell. So I can build a li-ion pack for my Prius C using 40x6 series-parallel cells or 240 cells. Nevermind the cost. The OEM pack uses 20 NiMH cells for total volume of 106*285*19.6*20mm, which is space enough for 4*4*18 = 288 21700 cells w room to spare. So I can install 40*7 series*parallel li-ion pack in my Prius C for total 3.6V*4Ah*280 = 4KWh, 4x OEM capacity, enough for ~15 miles EV range? But how to do it without setting off errors/throwing codes, or needing to modify OEM Battery Management System? The BMS has 20 voltage sensor leads for each of 20 OEM cells, nominally 7.2V each, which voltage is equal to 2 li-ion cells in series. So can I just connect the BMS sensor leads to one of my 40 cell series li-ion packs to maintain status quo for the BMS? Even better, could I multiplex the 7 series packs to the single BMS to achieve whole-pack management, and Prius computer/BMS happily ignorant? Anyone know if extra capacity alone could cause errors? Then how to charge it at home?
In a word, yes. I don't like discouraging anyone from hacking and modding, but a Prius is such a delicately balanced network of interdependent systems that changing a major assembly like the battery is going to demand changes to nearly every other part of the propulsion system and especially the various ECUs regulating them. If you gut the whole hybrid system out of there and use it as a glider shell you'd have a much simpler project. Of course, the only real advantage to this is that the car already has a space defined for a large battery where your average Corolla or Focus donor car would not. That might not be enough of an advantage to matter. Good luck!
Thanks for reply. I was hoping someone else would jump in and encourage me. After more research I also found that battery SOC determined by Prius I guess thru current tracking in BMS and MG units. Seems that using the full potential of a much larger battery would require modification of native software then, which might be impossible or difficult w/ good potential to brick the car I imagine. Nimh HV battery and discharge 40 amps | PriusChat
haven't seen them in awhile. look in the appropriate forum, you should be able to find pertinent threads.
