Allen-Bradley 1747-BA Battery Backup Assembly

The Allen-Bradley 1747-BA Battery Backup Assembly is a lithium memory-backup power source for SLC 500 PLCs, designed to preserve program memory and data in CMOS RAM during power loss. This compact unit is roughly 0.58 inches in diameter and 1.04 inches long (about half‑AA size), providing back‑up energy to maintain the processor’s memory when main power is unavailable. Compatible with SLC 500 fixed controllers and 1747-L511 processors, the 1747-BA is commonly used with SLC 5/03, 5/04, and 5/05 CPU modules to retain programs across outages. As a dedicated replacement battery, it should be installed according to SLC 500 maintenance instructions to ensure memory retention and system reliability.