ABB 4944026-004 PLC Replacement Battery 7.2V 5000mAh

ABB 001-4944026-4/S Series — 7.2V Ni-Cd Replacement Battery (4944026-004)

This is a 7.2V, 5000mAh Ni-Cd battery that replaces the original backup cell in ABB PLC controllers. It maintains SRAM program memory and the real-time clock when mains power is interrupted. Confirmed fit across the 001-4944026-4/S, 3HAB9307-1, 3HAB9999-2, and 418446884 platforms, plus nine additional ABB controller variants.

• Cross-platform ABB fit: These ABB controller variants share the same 7.2V Ni-Cd cell format, connector pinout, and BMS handshake protocol. One battery covers the full listed range without wiring modification.
• Bench tested on actual hardware: We cycled this cell under SRAM retention load and confirmed the BMS held the 5.5V minimum threshold required to keep program memory intact across simulated mains outages. Float charge acceptance was also verified against the controller's onboard charger circuit.
• Hot-swap procedure — mandatory for ABB controllers: Never remove this battery while the PLC is powered off. Always swap the cell with the controller live and in RUN mode. Removing the battery from a de-energised controller clears SRAM immediately — a full program reload from the programming device will be required if that happens.

PLC battery alarm not clearing after a confirmed good installation

ABB controllers do not auto-clear the battery fault flag once a new cell is fitted. The alarm is latched in firmware and must be manually acknowledged through the programming software — typically via the diagnostic or status register in the controller configuration tool. Until that reset step is completed, the fault stays active regardless of actual battery condition. Clear the latched alarm flag in the software after the swap, then verify the status register reads healthy.

New cell reading below rated voltage on first installation

Ni-Cd cells ship at storage voltage, which typically sits noticeably below the 7.2V rated value. This is not a fault. Once the cell is seated and the controller's onboard float charger picks it up, voltage climbs to full within a few hours of normal operation. If the cell has not recovered after 24 hours on the float charge, measure directly at the battery terminals — voltage below 6.8V at that point indicates a cell defect, and the unit should be replaced.