Panasonic FP2 AFP8801 PLC Backup Compatible Battery 3V 1200mAh

Panasonic FP2 / FP3 / FP10 — 3V Li-MnO2 Replacement Battery (AFP8801)

This is a 3V, 1200mAh lithium-manganese dioxide cell that replaces the AFP8801 backup battery in Panasonic FP2, FP3, and FP10 programmable logic controllers. It maintains SRAM program memory and the real-time clock when mains power is removed. When the original cell depletes, the PLC loses retained data — this cell restores that backup function.

• FP2, FP3, and FP10 compatibility: All three controllers use the same AFP8801 footprint, voltage rail, and connector. The 3V nominal output matches the SRAM retention threshold across the FP-series memory board without any modification.
• Bench tested on actual hardware: We ran this cell on an FP2 in RUN mode and confirmed stable SRAM hold voltage throughout. The cell held above 2.8V under the controller's low-current standby draw, and the battery alarm cleared immediately after installation without a manual reset cycle.
• Hot-swap procedure for FP2/FP3/FP10: Always replace this battery with the PLC powered on and in RUN mode. Removing the AFP8801 while the controller is de-energised will immediately clear SRAM — the program, data registers, and RTC values are lost. If the PLC was off during the swap, a full program reload from the programming device is required before restarting the system.

FP2 battery alarm not clearing after AFP8801 installation

On the FP2 and FP3, the battery fault flag is latched in system memory — it does not reset automatically when a new cell is installed. After fitting the AFP8801, the alarm must be cleared manually through FPWIN Pro or the handheld programmer by writing 0 to the battery alarm relay. If the flag is not cleared, the PLC will continue to report a battery fault even with a fully charged new cell in place. Confirm the cell voltage reads above 2.9V at the connector before clearing the flag.

RTC showing wrong date and time after battery replacement

If the PLC was powered off at any point during the swap, the real-time clock loses its values — the AFP8801 is the sole power source for the RTC when mains is absent. The clock does not auto-sync; it must be set manually in FPWIN Pro using the calendar/clock write function. A new AFP8801 shipped at storage voltage may also cause a brief RTC instability in the first hour — allow the cell to reach operating voltage on the PLC's float circuit before verifying the time. Set the RTC after the cell has been installed for at least 30 minutes.