Panasonic BR-AGCF2W 6V PLC Backup Replacement Battery 2200mAh

Panasonic BR-AGCF2W — 6V Li-MnO2 Replacement Battery (BR-ACF2P / BR-AGCF2P)

This is a 6V 2200mAh lithium manganese dioxide cell that replaces Panasonic BR-AGCF2W, BR-ACF2P, and BR-AGCF2P part numbers. It fits PLCs and industrial controllers where a dedicated backup cell maintains SRAM program memory and real-time clock data when main power drops. Dimensions are 45mm × 34mm × 17mm — verify physical fit before ordering.

• PLC backup cell application: These three Panasonic part numbers share the same voltage rail, footprint, and connector. They power only the SRAM retention and RTC circuits — draw is microamp-level, but voltage must stay above the controller's memory-hold threshold or the program is gone.
• Bench tested on actual hardware: We confirmed open-circuit voltage at 6.0V on delivery and verified stable load response under the microamp drain typical of PLC memory retention circuits. The cell held voltage within spec across the full test window.
• Hot-swap protocol — critical for this cell type: Always replace this battery with the PLC powered on and in RUN mode. Removing the cell while the controller is off collapses SRAM voltage instantly. If that happens, the program is erased and must be reloaded from a connected programming device.

PLC losing program memory after battery swap

SRAM in most PLCs is entirely battery-backed — there is no secondary hold circuit. The moment this cell is disconnected and the controller loses main power, SRAM voltage collapses in milliseconds. If the swap was done with the PLC powered off, or if the controller de-energised during the swap, the program is gone. The fix is a full program reload via the programming terminal — there is no recovery from SRAM loss without it. Prevent this by always confirming main power is live and the PLC is in RUN mode before touching the battery connector.

Battery alarm not clearing after the new cell is installed

Most PLCs latch the low-battery alarm in firmware — it does not reset automatically when a new cell is fitted. The alarm stays active until it is cleared manually in the programming software, typically through the diagnostic or status menu. On some controllers the cell also needs a short float period to rise from storage voltage before the firmware accepts it as healthy. If the alarm persists after clearing, check the cell voltage under load — it should read at or above 5.8V within a few hours of installation.