IBM ServeRAID M5000 3.7V Replacement Battery 46M0917

IBM ServeRAID M5000 Series — 3.7V Li-ion Replacement Battery (46M0917)

This is a 3.7V, 1500mAh Li-ion cache backup battery for IBM ServeRAID M5000 and M5015 RAID controllers, as well as IBM System x3250 M3 and x3630 M3 7377 platforms. It powers the controller's write cache during an unexpected power loss, protecting pending write operations until the system recovers. OEM part numbers covered include 46M0917, 43W4342, 46M0930, 46M0931, 67Y0186, and 81Y4559.

• M5000 and M5015 controller compatibility: Both controllers share the same cache backup architecture, voltage rail, and BMS handshake protocol. The battery connects via the same physical connector and communicates state-of-charge data to the controller firmware — no hardware modification needed.
• Bench tested on actual hardware: We ran this cell on an M5015 controller under StorCLI monitoring. The BMS handshake completed cleanly, voltage held at 3.7V nominal, and the controller accepted the cell without firmware flags on the initial connection.
• Learn cycle requirement after installation: After fitting this battery, trigger a learn cycle from the management interface — StorCLI: /cx bbu start learn, or ONTAP: system controller battery show. The controller stays in write-through mode until the learn cycle completes and recalibrates the backup window estimate against the new cell. This typically takes 24–72 hours under normal load.

RAID controller staying in write-through mode after battery swap

Write-through mode means the controller is not trusting the battery to protect cache during a power event. After a battery swap, the controller does not automatically recalculate the backup window — it waits for a full learn cycle to complete before switching back to write-back mode. Until that cycle runs and passes, write performance stays reduced and the management console reports the battery as unverified. Run StorCLI /cx bbu start learn or the equivalent ONTAP command to kick the cycle off manually rather than waiting for the scheduled trigger.

Management console showing a battery error days after installation

This catches a lot of users off guard — the controller looked fine at boot, then flagged a battery error 48 or 72 hours later. The scheduled battery self-assessment runs on a timed interval set in firmware, not at the moment of installation. If the learn cycle has not completed by the time that assessment fires, the controller logs a failure because the backup window estimate is still blank. Check the learn cycle status first with StorCLI /cx bbu show — if the cycle is still in progress, the error clears once it finishes and the backup window recalculates to at least 72 hours at 3.7V nominal.