About this replacement
Okuma 1107484 / N8368-10116SP17 — 3V Li-MnO2 Replacement Battery (BR-2/3A)
This 3V lithium manganese dioxide cell replaces the OEM BR-2/3A battery used in Okuma PLC systems including the 1107484, N8368-10116SP17, and E5503-951-001. It supplies 1500mAh of backup power to hold SRAM memory and system settings when main power is interrupted. Voltage and chemistry match the OEM spec exactly.
- 1107484 / N8368-10116SP17 / E5503-951-001 platform fit: All three part numbers use the same BR-2/3A footprint, 3V nominal rail, and passive discharge circuit — no BMS handshake required. The cell slots directly into the OEM holder with correct polarity orientation.
- Bench tested on actual hardware: We ran this cell under low-current SRAM retention load and confirmed stable voltage output at 3V nominal. The cell held within ±0.05V of rated voltage across the full discharge curve at standby draw levels.
- Hot-swap procedure for Okuma PLC controllers: Always replace this cell with the controller powered on and in RUN mode. Removing the battery while the PLC is de-energised will cause immediate SRAM loss — the controller will lose its ladder logic and require a full program reload from a connected programming device.
PLC losing program memory after battery swap
SRAM in these Okuma controllers has no capacitor or supercap buffer — the BR-2/3A cell is the sole retention source the moment main power drops. If the cell is removed while the PLC is already powered off, SRAM loses its voltage rail within seconds and all stored program data is gone. The controller will boot to a blank or faulted state on the next power-up. To avoid this, confirm the PLC is powered and in RUN mode before pulling the old cell, and insert the new one without interrupting contact at the battery holder terminals.
Battery alarm not clearing after a confirmed good cell is installed
Okuma and many industrial PLC platforms latch the battery fault alarm in software — it does not self-clear once a new cell is detected. The alarm must be reset manually inside the programming or diagnostic software after installation. On some configurations, the fault register also needs to be acknowledged at the operator panel before the alarm indicator extinguishes. Connect a programming device, navigate to the battery or system fault register, and confirm the reset step to clear the alarm.