Quite many changes were done to the initial circuit diagram along the way. The changes were governed by the idea of not needing to alter the original wiring. The circuit diagram shown above shows the current state of the Corolla eFX electrical connections. I am currently happy with it as everything seems to work well.
The biggest change to the original circuit diagram are the six parallel connected power MOSFETs that are located between the 12V battery negative terminal and the chassis. They were added to boost the discharge current capability of the PCM circuit from 20A up to about 100A. The gates of these MOSFETs are controlled by the same gate drive that controls the 12V battery pack PCM discharge MOSFETs. This way when the PCM notices an undervoltage situation the MOSFETs are turned off protecting the lifepo4 cells from potential damage.
The other major change was the addition of the 72V to 12V isolated power supply. This change made it possible to use a common 12V relay to wake up the motor controller. It also provided an isolated 12V power supply to be used by the panel meters. The 72V to 12V isolated power supply chosen is actually a low cost plug type offline AC/DC power supply that needs only about 50Vdc to start up. Not all of them do, but many of them do start with a lot lower voltages than the typically rated voltage range of 96Vac...250Vac. Of course, if used with a lower than specified input voltage the output current can not be expected to reach rated values.
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