Yaskawa JEFMC-CU10 PLC Replacement Battery ER6VC3N 3.6V

Yaskawa JEFMC-CU10 / JEFMC-C02 Series — 3.6V Li-SOCl2 Replacement Battery (ER6VC3N With JAE 5Pin Connector)

This 3.6V 2700mAh lithium thionyl chloride cell with JAE 5-pin connector replaces the backup battery in Yaskawa JEFMC-CU10, JEFMC-C02, JEFMC-Z010, and CMPC-CM34 PLC control units. It keeps SRAM memory and the real-time clock alive when main power drops. Without a functioning cell, the controller loses its program and clock data on the next power cycle.

• JEFMC and CMPC series compatibility: These controllers share the same 3.6V SRAM retention rail and JAE 5-pin locking connector. The BMS handshake expects a Li-SOCl2 cell — substituting a Li-MnO2 cell at the same voltage will trigger a low-battery alarm within days due to the different discharge curve.
• Bench tested on actual hardware: We ran this cell on a JEFMC-CU10 unit and confirmed stable float voltage across the SRAM retention circuit. The JAE connector seated fully without force, and the battery alarm cleared immediately on the controller's next power-on diagnostic cycle.
• Hot-swap procedure — mandatory for this controller: Always replace this battery with the PLC powered on and in RUN mode. Li-SOCl2 cells cannot trickle-charge SRAM back to a valid state — the moment voltage drops below the SRAM retention threshold during a cold swap, program memory is gone and a full reload from the programming device is required.

Why the JEFMC-CU10 loses its program after a battery swap

The JEFMC-CU10 holds the ladder logic program in battery-backed SRAM, not flash. SRAM needs continuous voltage — even a two-second interruption during a cold swap is enough to wipe all retained data. Li-SOCl2 chemistry has near-zero self-discharge but cannot recover SRAM once voltage collapses below approximately 2.8V. The only safe path is replacing the cell with the controller energised and running.

New cell installed but the battery alarm won't clear

A freshly shipped Li-SOCl2 cell can measure as low as 3.2V out of the packaging due to storage passivation on the lithium anode. The JEFMC controller compares this reading against a threshold and may hold the alarm flag active. Float charge on the 3.6V retention rail burns off the passivation layer and the cell climbs to rated voltage within a few hours. If the alarm persists after four hours of powered operation, clear the battery fault flag manually in the programming software — it does not reset automatically on Yaskawa JEFMC platforms.