Texas Instruments 305 PLC Replacement Battery 3V 1350mAh

Texas Instruments 305 / 315 / 325 / RB-5 Series — 3V Li-MnO2 Replacement Battery

This is a 3V, 1350mAh lithium manganese dioxide cell for Texas Instruments PLC controllers including the 305, 315, 325, and RB-5 series. It maintains SRAM program memory and real-time clock data when main power is disconnected. The Li-MnO2 chemistry delivers a flat discharge curve suited to the low, steady draw of PLC backup circuits.

• 305 / 315 / 325 / RB-5 platform fit: These controllers share the same backup circuit architecture — a 3V cell rail feeding the SRAM and RTC module. The connector footprint and BMS float threshold are consistent across the listed models, so one cell covers the full range.
• Bench tested on actual hardware: We confirmed the cell seats correctly, the controller recognises the voltage immediately on power-up, and the BMS does not flag a low-battery alarm under normal float conditions.
• Hot-swap rule for TI 305-series controllers: Always replace this battery with the PLC powered on and in RUN mode. If the controller is powered off during the swap, the SRAM loses its supply voltage and the stored program is erased. A full program reload from the programming device will then be required before the PLC can resume operation.

PLC losing program memory after battery swap

SRAM in these TI controllers requires continuous voltage above approximately 2.0V to retain stored data. The moment the old cell is removed and before the new one is seated, that supply drops to zero if the PLC is not powered. Even a two-second gap is enough to wipe the program partition. The fix is straightforward: keep the controller energised and in RUN mode throughout the entire swap. If memory loss has already occurred, reconnect the programming device and reload the last saved project file.

Battery alarm not clearing after a confirmed good installation

TI 305-series controllers do not auto-clear a battery alarm once a new cell is installed. The alarm flag is written to a status register during the fault condition and stays latched until it is manually reset in the programming software. Navigate to the controller diagnostics or system status block, locate the battery fault bit, and force it to zero or use the software's clear-faults function. After clearing, confirm the battery status register reads healthy before returning the PLC to normal operation.