LSI MegaRAID 9260-8i BAT1S1P Compatible Battery 3.7V 1500mAh

LSI MegaRAID 9260-8i Series — 3.7V Li-ion Replacement Battery (BAT1S1P)

This 3.7V, 1500mAh Li-ion cell replaces the cache backup battery on LSI MegaRAID 9260-8i, 9260, 9261, and 9280 RAID controller cards. It powers the controller's DRAM cache during unexpected power loss, protecting in-flight writes from being lost or corrupted. The OEM part numbers BAT1S1P, L3-25343-13B, and IBBU08 all cross-reference to this same cell.

• MegaRAID 9260 and 9280 platform fit: These controllers share the same BBU socket, connector pinout, and BMS handshake protocol. The IBBU08 module mounts the cell into the same carrier used across the 9260 and 9280 families, so one cell services the entire range.
• Bench tested on actual hardware: We ran this cell through charge, discharge, and BMS negotiation on a 9260-8i. The controller accepted the cell, completed communication handshake, and transitioned from write-through to write-back after the learn cycle finished.
• Post-swap initialisation on the 9260-8i: After fitting the new cell, trigger a battery learn cycle from StorCLI using storcli /cx bbu startlearncycle. The controller holds write-through mode until the learn cycle completes and the backup window is recalibrated against the new cell's actual capacity.

RAID controller staying in write-through mode after battery swap

Swapping the cell does not automatically return the controller to write-back mode. The MegaRAID BBU module must complete a full learn cycle — charge, full discharge, and recharge — before the firmware recalculates the backup window. Until that cycle finishes, the controller treats the backup window as unknown and defaults to write-through as a safety measure. On a 9260-8i under normal server load, the learn cycle typically runs 24–72 hours. Monitor progress with storcli /cx bbu show and check that the backup window value is no longer showing zero.

Management console showing a battery error days after installation

LSI MegaRAID controllers do not run a battery assessment at boot. The BBU self-test runs on a timed interval set in firmware — often 90 days by default, but some builds run a verification pass within the first week of detecting a new cell. If the learn cycle had not completed by the time that timed check ran, the controller logs a battery error even though the cell is functional. Check the learn cycle status first with storcli /cx bbu show all. If the learn cycle shows complete and the absolute state of charge is above 80%, clear the event log and allow the next scheduled assessment to run.