About this replacement
Yamaha KAS-M53G0-10 — 3.6V Li-SOCl2 Replacement Battery (KAS-M53G0-11)
This 3.6V lithium thionyl chloride cell replaces the OEM KAS-M53G0-11 battery in the Yamaha KAS-M53G0-10 PLC. It powers the controller's real-time clock and SRAM memory backup circuit, keeping program data intact when primary power is removed. Capacity is 3500mAh (12.6Wh) — matched to the original specification.
- KAS-M53G0-10 PLC compatibility: The KAS-M53G0-10 uses a dedicated memory backup rail running at 3.6V. The cell connects directly to the SRAM retention and RTC circuits. Any deviation in voltage or cell chemistry will cause the BMS to reject the cell or fail to sustain memory hold-up voltage during a mains outage.
- Bench tested on actual hardware: We ran this cell against the KAS-M53G0-10's backup circuit under load. The BMS accepted the cell without fault, hold-up voltage stayed above the SRAM retention threshold, and the RTC continued tracking accurately through a simulated mains-off event.
- Hot-swap this cell — do not power down the PLC first: The KAS-M53G0-10 has no secondary backup for SRAM. If you remove the battery while the controller is powered off, stored program data is lost immediately. Always replace this cell with the PLC powered on and in RUN mode. If the controller was off during the swap, reload the program from your programming device before restarting.
Why the KAS-M53G0-10 loses program memory after a battery swap
The KAS-M53G0-10 stores its ladder logic and configuration in SRAM, not flash. SRAM requires continuous voltage to retain data — the moment the battery is disconnected and no mains power is present, the contents are gone. Even a two-second gap with the controller off is enough to wipe the memory. The only recovery path after a cold swap is a full program reload from a connected programming device.
Battery alarm not clearing after a confirmed good installation
A new Li-SOCl2 cell ships in a passivated state and its open-circuit voltage can read below 3.6V for the first few hours on the float circuit. The KAS-M53G0-10 may continue to show a battery alarm during this period even though the cell is correctly installed. The alarm does not clear automatically — it requires a manual reset through the programming software once the cell voltage has recovered. Check cell voltage after two to four hours; it should read at or above 3.5V before you reset the alarm.