NetApp 271-00027 Compatible Battery 7.2V 5200mAh Li-ion

NetApp NEX-90089 / FAS3240 / ES3259 — 7.2V Li-ion Replacement Battery (271-00027)

This 7.2V 5200mAh Li-ion cell replaces the cache backup battery in NetApp NEX-90089, FAS3240, and ES3259 RAID controller modules. It powers the controller's write cache during a power loss event, allowing the system to flush dirty data to storage before shutdown. Voltage and capacity match OEM spec: 7.2V, 5200mAh (37.44Wh).

• NEX-90089, FAS3240, ES3259 compatibility: All three platforms share the same backup module form factor and BMS handshake protocol. The controller validates cell voltage range on every boot — this cell sits within that acceptance window across all listed variants.
• Bench tested on actual hardware: We ran a full charge and discharge cycle and confirmed BMS communication handshake. The cell accepted charge without fault flags and reported backup window data to the controller management interface after a completed learn cycle.
• Learn cycle initiation after swap: After fitting this battery, trigger a learn cycle from the controller interface — ONTAP: system controller battery show; LSI/Broadcom: StorCLI /cx bbu show. The controller holds in write-through mode until the learn cycle recalibrates the backup window estimate against the new cell's actual capacity.

RAID controller staying in write-through mode after battery swap

Write-through mode is not a fault — it is the controller's default safe state when the backup window has not been confirmed. After a battery swap, the controller does not automatically trust the new cell's reported capacity. It requires a completed learn cycle to calculate a verified backup window before switching back to write-back mode. Until that cycle finishes, all writes bypass the cache and go directly to disk, which is expected behaviour and not a sign of a failed battery.

ONTAP or StorCLI reporting a battery error days after installation

Battery assessment in ONTAP and LSI-based controllers runs on a timed interval, not at boot. If the scheduled self-test fires before the learn cycle has fully completed, the controller logs an error because the backup window estimate is still undefined. This is not a cell defect. Allow 24–72 hours of normal operation for the learn cycle to complete, then re-check status with system controller battery show — the error clears once a valid backup window value is recorded.