NetApp C3300 RAID Controller Replacement Battery 3.7V 5400mAh

NetApp C3300 / FAS3020 / NVRAM5 — 3.7V Li-ion Replacement Battery (271-00002)

This 3.7V, 5400mAh Li-ion cell replaces the OEM backup battery on NetApp C3300, FAS980C, FAS3020, and NVRAM5 RAID controllers. It holds cache memory during unexpected power loss so the controller can flush dirty data and shut down cleanly. Voltage and capacity match the 271-00002 specification.

• C3300, FAS3020, and NVRAM5 compatibility: These controllers share the same 3.7V single-cell backup architecture and use the same BMS handshake to monitor cell state-of-charge. A matching cell voltage at rest prevents the controller from flagging a hardware mismatch at boot.
• Bench tested on actual hardware: We cycled this cell through a full learn sequence on a RAID controller bench. The BMS accepted the cell, transitioned from write-through to write-back once the backup window recalibrated, and reported a clean battery status in ONTAP after the learn cycle completed.
• Post-swap controller mode: After swapping this battery, run system controller battery show in ONTAP to confirm the learn cycle has started. The controller holds in write-through mode until the cycle finishes — this is normal and takes up to 72 hours under typical load. Do not force write-back mode manually before the cycle completes.

RAID controller staying in write-through mode after battery swap

After installing a new cell, the controller does not automatically switch back to write-back mode. It waits for the BMS to complete a learn cycle, which measures the actual backup window the new cell can deliver. Until that number is established and meets the controller's minimum threshold, write-back stays disabled. Run system controller battery show in ONTAP to track progress — the cycle typically completes within 24 to 72 hours under normal I/O load.

ONTAP reporting a battery error days after installation

This catches many users off guard — the battery looks fine at boot, then an error appears one to three days later. NetApp controllers run a scheduled battery self-assessment on a timed interval, not at power-on. If that assessment fires before the learn cycle has fully recalibrated the backup window against the new cell, the controller logs a fault. Let the learn cycle finish first, then check system controller battery show — the status should clear to "OK" once the backup window estimate stabilises above the controller's minimum threshold.