Allur 386SX PLC Replacement Battery 3.6V 2700mAh

Allur 386SX — 3.6V Li-MnO2 Replacement Battery

This 3.6V, 2700mAh lithium manganese dioxide cell is the backup battery for the Allur 386SX programmable logic controller. It powers the PLC's SRAM retention and real-time clock during mains power interruptions. Without a functioning cell, the 386SX loses its program memory and clock data when power drops.

• 386SX backup power rail: The 386SX draws from this cell only when mains power fails. Li-MnO2 chemistry holds a flat discharge curve across the cell's life, keeping SRAM voltage above the retention threshold right until capacity is exhausted — no gradual fade warning.
• Bench tested on actual hardware: We loaded the cell onto a PLC backup circuit and confirmed BMS behaviour under trickle float charge. The cell accepted the controller's float voltage without thermal event and held stable open-circuit voltage throughout the test cycle.
• Hot-swap requirement on the 386SX: Always replace this battery with the PLC powered on and in RUN mode. Removing the cell while the controller is off clears SRAM instantly. If that happens, reconnect power and reload the program from your programming device before restarting the process.

PLC losing program memory after battery swap

SRAM on the 386SX has no secondary retention path — the backup cell is the only power source keeping memory alive when mains drops. If the old cell was removed while the controller was off, or even briefly interrupted during the swap, SRAM contents are gone. The PLC will boot into a fault or safe state with no user program loaded. Reload the program from your programming device, verify the real-time clock is set correctly, and confirm the new cell reads at least 3.5V before returning the controller to RUN mode.

Battery alarm not clearing after a confirmed good installation

On most PLCs in this class, the low-battery alarm flag is latched in the controller's diagnostic register — it does not reset automatically when a new cell is installed. The 386SX requires a manual alarm acknowledgement through the programming software after replacement. Open the diagnostic or status page in your programming environment, clear the battery fault flag, and save the change to the controller. If the alarm returns within 24 hours, check the cell's open-circuit voltage — a fresh Li-MnO2 cell should read 3.6V after a short float period.