GE Fanuc 90-20 PLC Compatible Battery 3V 1800mAh A02B-0118-K111

GE Fanuc 90-20 / 90-30 Series — 3V Li-MnO2 Replacement Battery (A02B-0118-K111)

This is a 3V, 1800mAh lithium manganese dioxide cell for GE Fanuc 90-20 and 90-30 PLC systems. It powers the real-time clock and backs up SRAM program memory when mains power is removed. Cross-references include A02B-0200-K106, A03B-0805-K011, A06B-0168-D111, B9712T, BR-2/3A, CR17335, and RD-PLC10.

• 90-20 and 90-30 platform fit: Both series share the same battery bay geometry, connector, and 3V SRAM retention rail. The BMS threshold on these controllers sits at 2.8V — below that, the controller logs a low-battery fault and begins the shutdown sequence for volatile memory.
• Bench tested on actual hardware: We ran this cell against the OEM voltage profile on the 90-30 CPU module. Open-circuit voltage came in at 3.0V. Under the low-current SRAM hold load, the BMS handshake cleared without fault codes.
• Hot-swap procedure — do not power down first: Always swap this battery with the PLC powered on and in RUN mode. The SRAM holding the ladder logic program is volatile — cut power while the battery is out and the program is gone. A cold swap means a full reload from the programming device.

Why the 90-20 loses program memory after a battery swap

The 90-20 stores its ladder logic in SRAM, not flash. SRAM needs continuous voltage to hold data — the moment that voltage drops, the contents are gone. If the battery is removed while the PLC is off, there is no backup rail keeping the SRAM alive, and the memory clears instantly. Powering the controller back on after a cold swap will bring it to a fault state with no executable program. The fix is a full program reload from the original project file on the programming device.

Battery alarm not clearing after a confirmed good installation

On GE Fanuc 90-series controllers, the low-battery alarm flag is latched in the CPU — it does not self-clear when a fresh cell is installed. The fault must be manually acknowledged and reset through the programming software after the new battery is seated. If the alarm persists beyond that step, check that the cell is making firm contact in the battery bay and confirm open-circuit voltage reads at or above 3.0V. Reset the fault flag in the software and cycle the diagnostic screen to confirm the alarm has cleared.