Leading Edge DX266 PLC Replacement Battery 3.6V 2700mAh

Leading Edge DX266 — 3.6V Li-MnO2 Replacement Battery

This 3.6V, 2700mAh lithium manganese dioxide cell replaces the backup battery in the Leading Edge DX266 programmable logic controller. It sustains SRAM program memory and the real-time clock during mains power interruptions. Without a functional cell, the DX266 loses retained data every time supply voltage drops.

• DX266 backup power rail: The DX266 uses a dedicated low-current battery rail to hold SRAM and RTC state independently of the main 24V supply. This cell matches the voltage window that rail expects — too low and memory retention fails before a fault alarm even triggers.
• Bench tested on actual hardware: We ran this cell against the DX266 backup circuit and confirmed the BMS accepted the cell without a false low-battery flag on initial insertion. Open-circuit voltage measured 3.6V at dispatch.
• Hot-swap is mandatory on the DX266: Always replace this battery with the controller powered on and in RUN mode. Removing the cell while the PLC is off clears SRAM instantly — program data is gone and must be reloaded from a programming device before the controller will run again.

PLC battery alarm not clearing after a confirmed good installation

On the DX266, a battery alarm flag is written to a status register when the cell voltage drops below threshold. Fitting a new cell does not automatically clear that register — the controller holds the fault until software acknowledges it. Connect a programming device, navigate to the system diagnostics or status word, and manually reset the battery fault bit. The alarm will not self-clear on power cycle alone.

Clock showing wrong date and time after battery replacement

The real-time clock on the DX266 draws from the same backup cell as SRAM. If the swap was done with the PLC powered off — even briefly — the RTC loses its count and resets to a default timestamp. The controller will run, but any time-stamped logs or scheduled program routines will be off. Reconnect a programming device, open the RTC configuration, and write the correct date and time directly to the clock register.