The battery is monitored using the MPU's AD-Converter
The address of ADC_ADDRA is 0xA4610080.
The functionality is identical to the 7730-ADC, though the address is a bit different on the 7730.
In legacy systems with backup battery , the ADC-channel C has been used, to monitor the backup-battery.
The Prizm's GetBatteryVoltage syscall shows no signs of accessing channel C.
int GetMainBatteryVoltage( int one );
The parameter one should be always 1.
Seems to return the battery voltage*100.