Yes, according to the specs, there is a field replaceable battery that backs up the real time clock. It does not back up the application.
Search the www for this manual 2711-in009_-en-p.pdf
Open it and search for battery for replacement instructions. I did not easily find a part number for a replacement.
EDIT: it is also discussed in the PV Standard User Manual where they list the part number as a real time clock module for a Series F:
2711-NB3