Schneider TSX17 PLC Replacement Battery 3.6V 5400mAh

Schneider TSX17 — 3.6V Li-SOCl2 Replacement Battery (2XSL360/131)

This 3.6V Li-SOCl2 cell replaces the internal backup battery in the Schneider TSX17 programmable logic controller. It maintains real-time clock accuracy and preserves program memory during power loss or planned shutdowns. Capacity is 5400mAh (19.44Wh), matching the original specification.

• TSX17 PLC compatibility: The TSX17 series uses a dedicated 3.6V lithium thionyl chloride cell for RTC and SRAM backup. Voltage match is critical — the memory backup circuit draws from this cell continuously, and any deviation causes data loss or clock drift under mains interruption.
• Bench tested on actual hardware: We ran this cell through simulated mains-off backup cycles on a TSX17 unit. The BMS held stable voltage across the backup rail, and the RTC retained accurate time through repeated power interruptions without reset.
• Post-installation clock sync: After fitting this cell, force a manual RTC sync through the TSX17 programming software before returning the controller to service. Li-SOCl2 cells can exhibit a brief voltage stabilisation period after first load, and syncing the clock at this point prevents time-stamp errors in logged events.

Why the TSX17 loses program data even with a new battery fitted

Li-SOCl2 cells develop a passivation layer on the anode during storage. On first load, this layer causes a brief voltage dip that can fall below the TSX17 memory backup threshold before the cell stabilises. If the controller is powered down immediately after battery replacement, that dip can register as a supply fault and trigger a memory clear. Allow the cell to operate under normal mains power for at least an hour before any planned shutdown — this burns off the passivation layer and the backup voltage stabilises above 3.2V.

RTC showing wrong time after mains restoration — not a clock fault

When the backup battery is deeply depleted, the TSX17 RTC loses its register contents entirely rather than drifting — the controller restores power with the clock reset to a default epoch value. This is often misread as a clock module fault. The cause is the old cell dropping below the minimum retention voltage, typically around 2.0V, before replacement. After fitting this cell, resync the RTC through your programming terminal and confirm the timestamp is writing correctly to the event log before leaving the installation.