IBM 5162  -  Battery

The 5162's battery is a BR-P2 (or CR-P2), and it resides in a dedicated compartment within the 5162.
Access to the battery compartment is via a door at the rear of the 5162.

If you are changing the battery because of a 161 error, then note that after battery replacement, the 161 will remain until you complete the SETUP procedure.