IBM ServerRAID 8K 3.7V 1800mAh Replacement Battery 25R8076

IBM ServerRAID 8K / System X3650 — 3.7V Li-ion Replacement Battery (25R8076)

This 3.7V 1800mAh Li-ion cell replaces the cache backup battery on IBM ServerRAID 8K and ServeRAID 8K SAS RAID controllers, including installations in the System X3650 and ABT-200. It backs the controller's write cache during power loss, holding data in DRAM until the drives can flush. Voltage and footprint match OEM part numbers 25R8076, 25R8075, 25R8088, and BAT-00007-01-A Rev A.

• ServerRAID 8K and 8K SAS compatibility: Both controllers share the same 3.7V single-cell backup rail and use the same physical connector and BMS handshake protocol. One cell fits both variants without modification.
• Bench tested on actual hardware: We ran this cell on an 8K controller under simulated cache load. The BMS accepted the cell, reported a valid voltage, and held the controller in write-back mode once the learn cycle completed. No error flags were thrown after the recalibration pass.
• Learn cycle initiation after swap: After fitting this cell, trigger a battery learn cycle from the controller's management interface — StorCLI: storcli /cx bbu start learn. The controller stays in write-through mode until the cycle runs, recalibrates the backup window estimate against the new cell's actual capacity, and clears the conditioning flag. Skipping this step leaves write caching disabled indefinitely.

RAID controller staying in write-through mode after battery swap

The 8K controller does not automatically switch back to write-back mode when a new cell is installed. It requires a completed learn cycle before it trusts the backup window calculation. Until that cycle runs and validates the cell's charge curve, the controller treats the battery as unqualified and keeps caching conservative. Run storcli /cx bbu show to confirm learn status, then force a cycle if it hasn't started within 30 minutes of installation.

Management console showing battery error two or three days after installation

IBM's RAID management tools schedule their full battery assessment on a timed interval, not at boot. If the assessment window falls 48–72 hours after your swap, the console will flag an error until that scheduled test runs against the new cell and passes. This is not a fault with the cell. Check the battery status log timestamp — if the error appeared exactly on the assessment interval, let the cycle complete. The flag clears once the assessment records a healthy voltage above 3.5V and a valid backup window.