Based on the initial Avionics scheme i collected the available information around power loads and i simulated the different power loads (max and normal) for the different phases of the flight.
Then i distributed the loads on the different "busses":
Battery with the minimal equipment (G5, 1 COM/GPS/NAV, Transponder, Flaps and trims and basic lights.
ALT2 will be on standby and its regulator activate the backup alternator if it detects issues on the main alternator (under voltage). The Backup alternator mounted on the vacuum pump drive will provide 40 AMP