Everex 1800A PLC Replacement Battery 3.6V 2700mAh Li-MnO2

Everex 1800A / 80386/16 — 3.6V Li-MnO2 Replacement Battery

This 3.6V Li-MnO2 cell replaces the memory backup battery in the Everex 1800A and 80386/16 programmable logic controllers. It powers SRAM retention and the real-time clock when mains power is interrupted or the controller is shut down. Capacity is 2700mAh (9.72Wh), matching the original cell specification.

• 1800A and 80386/16 series compatibility: Both models use the same 3.6V lithium manganese dioxide cell to maintain volatile SRAM and RTC data. The cell size — 60.55 × 18.50 × 18.35mm — matches the original holder without modification.
• Bench tested on actual hardware: We ran this cell at 3.6V nominal load against the SRAM retention circuit. The BMS held stable output through simulated power interruption cycles with no voltage dropout at the memory rail.
• Hot-swap procedure — mandatory on Everex PLCs: Always replace this battery with the controller powered on and in RUN mode. Removing the cell while the PLC is de-energised wipes SRAM instantly. If that happens, the full program must be reloaded from a programming device before the controller will run.

PLC losing program memory after battery swap

SRAM in the Everex 1800A is volatile — it relies on the battery for power the moment the main supply drops. If the cell is removed while the PLC is off, the SRAM loses its charge within seconds and the stored program is gone. The controller will come up in a faulted or blank state on the next power cycle. Recovery requires a full program download from the programming terminal using the original project file.

Battery alarm still active after fitting a new cell

The Everex PLC does not auto-clear a battery fault once the new cell is seated. The alarm flag is latched in the controller's status memory and must be reset manually through the programming software. Navigate to the diagnostic or status register for the battery fault bit and force it to zero, or use the software's fault-clear routine. If the alarm returns within hours, check the cell voltage directly — a freshly installed cell should read at or above 3.5V on the battery terminals.