"Service Battery Charging System" causes 12v to run down. "Service High Voltage Charging System" is different.Don't ignore this error message. Take your Volt to the dealer as soon as possible. In addition to preventing charging of the high voltage battery this error condition will cause your 12V battery to not be charged and you will be stranded as soon as the 12V battery runs down.
More here: http://gm-volt.com/forum/showthread.php?233881-Service-Battery-Charging-System-DTCs-P1F5A-P1F59-P0D26-P0D09-P1EBD-PIC6200-PIC6182/page8
Thanks. In my experience with my 2017 the issue that is the root cause of the Service High Voltage Charging System error message will also affect the 12V charging. All due to a defective 15 amp fuse that like Jessica Rabbit is not really bad it was just made that way."Service Battery Charging System" causes 12v to run down. "Service High Voltage Charging System" is different.