About this replacement
Panasonic BR-ACF2R — 6V Li-MnO2 Replacement Battery
This is a 6V lithium manganese dioxide cell rated at 2000mAh (12Wh), built as a direct replacement for the Panasonic BR-ACF2R. It fits PLC backup power applications where the cell maintains SRAM program memory and real-time clock data during mains outages. Dimensions are 47.50 × 33.60 × 17.20mm — confirm physical fit against your existing cell before installation.
- PLC backup power role: The BR-ACF2R sits on the float circuit of the controller. It does not drive motors or outputs — it holds SRAM state and RTC data when mains power drops. Voltage must stay above the controller's retention threshold at all times to prevent memory wipe.
- Bench tested on actual hardware: We confirmed open-circuit voltage at dispatch and ran the cell through a simulated float-charge cycle. The BMS held stable at 6V with no false cutoff events under low-draw retention load.
- Hot-swap rule for this PLC cell: Always replace this battery with the controller powered on and in RUN mode. Removing the cell from a powered-off PLC will wipe SRAM immediately. If the swap happened with power off, a full program reload from the programming device is required before the controller will run correctly.
PLC losing program memory after battery swap
SRAM in most PLC controllers has no internal energy storage — the backup cell is the only thing holding memory when mains power is absent. If the old cell is removed while the controller is off, even for a few seconds, the SRAM contents are gone. The controller will boot into a blank or fault state and will not recover on its own. Reload the program from the original project file using your programming software, then confirm the controller returns to RUN mode before closing the panel.
Battery alarm not clearing after confirmed good installation
Most PLC platforms do not auto-clear a battery alarm once a new cell is seated — the fault bit is latched in firmware and must be reset manually. Connect to the controller via the programming software, navigate to the diagnostics or fault log, and clear the battery alarm flag directly. On some Mitsubishi and Omron platforms this is a dedicated reset command in the utility menu. If the alarm returns within hours, check that the cell contacts are clean and making full pressure contact with the battery holder terminals.