Mitsubishi FX3U-32BL MELSEC‑F Backup Battery 3V

Mitsubishi Electric MELSEC‑F series backup battery for FX3G, FX3U, FX3GC, FX3UC, FX5U and FX5UC programmable logic controllers (PLCs). Maintains the contents of internal RAM memory during power‑off, including program data, power‑failure retention type auxiliary relays, data registers, link registers (W), file registers (R), and clock data. Replacement for FX3U PLC series.

Applications:

• Battery replacement in FX3G, FX3U, FX3GC, FX3UC main units

• Battery installation in FX5U, FX5UC CPU modules

• Retention of calendar and clock data in FX3/FX5 series systems

• Memory backup for systems using file registers (R) and link registers (W)

• Preventive maintenance and spare part stocking for MELSEC‑F PLCs

Core Specifications:

• Battery type: Lithium metal (connector type)

• Nominal voltage: 3 V DC

• Capacity: 540 mAh – 560 mAh (typical)

• Standard life: approx. 5 years at 25 °C ambient temperature

• Battery voltage monitoring: PLC data register D8005

• Mounting: Internal battery compartment (connector‑type)

Advanced Specifications:

• Memory backup functions:

  • Program memory retention in built‑in RAM

  • Power‑failure retention of auxiliary relays (M) and data registers (D)

  • Link register (W) and file register (R) backup

  • Sampling trace results storage

  • Clock data retention (real‑time clock)

• Operating / storage temperature (battery): –20 °C … +60 °C (refer to manufacturer manual)

• RoHS compliant (CE)

System Integration:

• This battery belongs to the Mitsubishi Electric MELSEC‑F series.

• Compatible with FX3G, FX3GC, FX3U, FX3UC, FX5U, FX5UC CPU modules (and other compatible MELSEC‑F series controllers).

• Device memory backup does not require a battery. However, to retain clock data for 10 days or more and to back up link registers (W) and file registers (R), the FX3U‑32BL battery is required.

• After battery installation, select Battery Mode: Use the battery in the FX parameter window of GX Developer or GX Works2.

• For detailed replacement procedures, battery life predictions and storage conditions, refer to the MELSEC‑F series Hardware Manual.

Compatibility:

• F2‑40BL – predecessor for MELSEC‑F series (different connector)

• FX2NC‑32BL – for FX2NC series (different connector)

• Current model → FX3U‑32BL (for FX3G/FX3U/FX3GC/FX3UC/FX5U/FX5UC)

• Recommended replacement (higher capacity) → FX3U‑32BL (this is the only OEM battery type for these FX3/FX5 series; refer to manufacturer compatibility list)