IBM 97P4846 RAID Controller Replacement Battery 3.7V 3400mAh

IBM 2780 RAID Controller — 3.7V Li-ion Replacement Battery (97P4846)

This 3.7V 3400mAh Li-ion cell replaces the backup battery on the IBM RAID controller cache module. It fits the 2780, 5580, 5708, and 5780 controller families, along with 23 additional compatible models. The battery holds write-cache data in SRAM during a power loss, protecting in-flight writes until the host recovers.

• Controller family compatibility: These controllers share the same cache backup architecture — single Li-ion cell, 3.7V nominal rail, same BMS handshake for learn-cycle signalling. One replacement cell covers the full range of affected IBM storage controllers listed above.
• Bench tested on actual hardware: We cycled this cell through a full charge and discharge sequence, confirmed BMS communication with the controller, and verified that the backup window estimate updated after the learn cycle completed. The cell held 3400mAh within normal tolerance across three consecutive cycles.
• Post-installation learn cycle: After fitting this cell, trigger a battery learn cycle from the management interface — use system controller battery show in ONTAP or StorCLI /cx bbu show for Broadcom/LSI platforms. The controller stays in write-through mode until that cycle completes and recalibrates the backup window against the new cell's actual capacity.

RAID controller staying in write-through mode after battery swap

Swapping the physical cell does not automatically switch the controller back to write-back mode. The controller's firmware holds write-through until it has completed a full learn cycle and confirmed the backup window meets its internal threshold — typically 72 hours or more under normal load. Until that cycle finishes, the controller treats the new battery as unverified. Check cycle status in ONTAP with system controller battery show; the state should move from "charging" through "learning" before write-back re-enables.

Management console reporting a battery error days after installation

IBM storage controllers run scheduled battery health assessments on a timed interval — not at the moment you install a new cell. If the system's next assessment window falls one or two days after the swap, the console may flag the battery as failed before the learn cycle has had time to complete. This is not a fault with the replacement cell. Wait for the scheduled assessment to run after the learn cycle finishes, then confirm the status clears. If the error persists beyond 96 hours post-cycle, check cell voltage directly — it should read between 3.6V and 4.2V at rest.