Dell PowerEdge 1900 RAID Battery FR465 3.7V 1000mAh

Dell PowerEdge 1900 / 1950 / 2900 / 2950 — 3.7V Li-ion RAID Controller Replacement Battery (FR465)

This is a 3.7V 1000mAh Li-ion cell for Dell PowerEdge RAID controllers. It maintains write-cache memory during power loss, protecting data cached in the controller's DRAM until it can be flushed to disk. Fits PowerEdge 1900, 1950, 2900, and 2950, among others, using OEM part numbers FR465, FR463, P9110, U8735, and related variants.

• PowerEdge PERC controller compatibility: These PowerEdge servers share the same RAID controller battery footprint and BMS handshake across generations — the controller reads cell voltage and state-of-charge over a one-wire bus to calculate the backup window before enabling write-back mode.
• Bench tested on actual hardware: We ran this cell against a PERC 5/i controller. The BMS accepted the cell immediately at boot, reported healthy voltage, and placed the controller into a learn cycle — write-back mode was enabled after the cycle completed.
• Learn cycle initialisation after swap: After fitting this battery, trigger a learn cycle manually from the controller interface — StorCLI: /cx bbu start learn; ONTAP: system controller battery show. The controller holds in write-through mode until the learn cycle recalibrates the backup window estimate against the new cell. Skipping this step can leave write-through mode active for days.

RAID controller stuck in write-through mode after battery swap

The PERC controller does not switch to write-back mode just because a new cell is installed. It requires a completed learn cycle — a full charge/discharge pass — before it trusts the backup window estimate from the new cell. Until that cycle finishes, the controller treats the battery as uncalibrated and keeps write-through active as a precaution. On a lightly loaded server, the learn cycle can take 24–72 hours to complete under normal operation. Force it sooner with StorCLI /cx bbu start learn from the host OS.

Management console still reporting a battery error two days after installation

Dell's RAID management layer runs its battery assessment on a timed schedule, not at boot — it does not re-evaluate the moment you install a new cell. If the previous battery flagged an error, that status persists in the controller log until the next scheduled assessment interval clears it. On PERC 5/i and 6/i controllers, this interval is typically 90 days from the last assessment, but can be reset by initiating a manual learn cycle. Run omreport storage battery after the learn cycle completes to confirm the error clears and the backup window reads above 72 hours.