FDK CR8-LHC PLC Backup Battery 3V 2000mAh Li-MnO2

FDK CR8-LHC — 3V Li-MnO2 Replacement Battery

This is a 3V lithium manganese dioxide cell rated at 2000mAh (6Wh), sourced to match the FDK CR8-LHC specification exactly. It fits PLC backup circuits where the cell maintains SRAM and RTC function during mains power loss. Voltage, footprint, and terminal configuration match the original OEM cell.

• PLC backup power application: This cell sits on a dedicated backup rail inside the PLC. Its sole job is holding SRAM contents and keeping the real-time clock alive when mains power drops. Li-MnO2 chemistry holds a flat 3V discharge curve across the full capacity range, which is exactly what SRAM retention circuits expect.
• Bench tested on actual hardware: We ran the CR8-LHC on a PLC backup circuit and confirmed the BMS presents stable voltage within expected tolerance from the moment the cell is seated. The cell does not require conditioning — it delivers working voltage on first contact.
• Hot-swap procedure — mandatory for this cell: Always replace this battery with the PLC powered on and in RUN mode. Removing the cell while the controller is powered off will erase SRAM contents immediately. If the PLC was off during the swap, a full program reload from the programming device is required before the controller can resume normal operation.

PLC losing program memory after a CR8-LHC swap

SRAM in most PLCs has no internal hold capacitor — the backup cell is the only power source the moment mains is removed. If the cell is pulled while the controller is off, the SRAM loses power instantly and the stored program is gone. This happens even if the swap takes only a few seconds. The fix is to reload the program from the original project file using the OEM programming software, then perform all subsequent battery swaps with the controller live and in RUN mode.

Battery alarm not clearing after a confirmed good CR8-LHC installation

Most PLC platforms — including Siemens S7 and Allen-Bradley ControlLogix — do not auto-clear the battery fault flag when a new cell is seated. The alarm is latched in firmware and requires a manual reset through the programming software or the controller's diagnostic interface. Connect to the PLC with the appropriate programming tool, navigate to the diagnostics or status register, and clear the fault manually. After the reset, confirm the battery status register reads healthy before closing the project.