Allen Bradley MicroLogix 1100 Compatible Battery 3V 850mAh

Allen Bradley MicroLogix 1100 — 3V Li-MnO2 Replacement Battery (1763-BA)

This 3V, 850mAh lithium-manganese dioxide cell replaces the 1763-BA in the Allen Bradley MicroLogix 1100 PLC. It maintains SRAM program memory and the real-time clock during power loss. Without a functioning cell, the controller loses its control logic and clock data the moment mains power drops.

• MicroLogix 1100 memory backup circuit: The MicroLogix 1100 uses a direct SRAM-backed architecture. The 1763-BA cell sits on a dedicated 3V rail that holds SRAM contents and RTC registers when the 24V supply is absent. No cell voltage means no retained state — the controller comes up blank after any power interruption.
• Bench tested on actual hardware: We ran this cell against the MicroLogix 1100 battery management circuit and confirmed correct float voltage acceptance, stable BMS handshake, and no low-battery fault flag at installation on a healthy controller.
• Hot-swap procedure on MicroLogix 1100: Always replace this cell with the controller powered on and in RUN mode. SRAM is volatile — remove the old cell while the PLC is de-energised and the program is gone. If a powered swap is not possible, have RSLogix 500 or Studio 5000 open and ready to reload the program immediately after.

SRAM retention voltage threshold on the MicroLogix 1100

The MicroLogix 1100 SRAM retention circuit requires a minimum of approximately 2.0V from the backup cell to hold memory contents. A depleted 1763-BA cell typically reads between 2.5V and 2.7V before the controller raises the low-battery alarm — well above the SRAM floor. By the time voltage drops below 2.0V, the cell is effectively dead and memory loss during any power interruption is certain. Swap the cell at the first confirmed low-battery alarm, not after.

Battery alarm not clearing after fitting a new 1763-BA cell

The MicroLogix 1100 does not automatically clear the battery alarm flag when a new cell is installed — it requires a manual reset inside RSLogix 500. Connect to the controller, navigate to Controller Properties, and clear the battery fault bit from the status file. If the alarm still persists after the reset, check that the cell contacts are fully seated; a partially inserted cell can read as absent to the BMS. A fully seated, healthy cell should register a float voltage of 3.0V at the terminals.