I hope to make this a running post for a one-off 2005 Prius PHEV conversion project utilizing an existing 4kwh Enginer. The target is a 10 kwh 35-Mile / 55+ mph pure EV; poor man's Volt! The Project For latest source and technical information see the PHEVCU git hub project Battery I'l be starting with the 4kw Enginer's, I need to add an additional 6kwh (10kw target) and end up at 240-260v pack. To do that I'll split the two Enginer packs into two again. That yields 100v/40Ah. I'll add an additional 48 cells of 40Ah LiFePO4, that gets me 250vnom / 40Ah, 9984Wh (lets call it 10kwh). I'll BMS the whole pack. ~$4k all said. From my EV experience, I will be building a proper insulated, ventilated and heated battery box. This makes a big difference in real world. Design: PHEVCU - Plug-in Hybrid Electric Vehicle Control Unit - Build a battery ECU (Dionmite w/dual Can-Bus') that can send the information the rest of the car (mostly HV ECU) wants.- Interface (CAN) with the Elcon 2500 Watt charger to set charge rates 0x346 / 0x34C: See other threads, but something will need to be done to spoof EV mode I'm confident I know how to get all that done, but I'm concerned about fail safes, over-speed, over/under-temp, etc? BTW; I'm a big fan of simplicity, I don't need/want any kind of display. This is my wife's car, if she has to touch a button or it goes into error-state, this is a total failure. Ideally, I should program the ECUs to fail gracefully into whichever mode makes most sense without feedback.