The PMIC (U10, MC34PF1550A4EP) on Portenta H7 can be used to charge a Li-on battery. But the battery is not used to power anything on the board, I am wondering what is the point of this battery charging function if the battery is only charged but is never used?
The PMIC will switch the load (connected to VSYSx) between battery (VBATTx) and external power (VBUSIN). The VSYSx output is used to derive the other voltages on the board by the DC-DC and LDO parts of the PMIC. What made you conclude the battery is never used?