Dell EMC Isilon NL410 RAID Battery 078-000-004 3.7V 2600mAh

Dell EMC Isilon NL410 / S210 / X-Series — 3.7V Li-ion RAID Controller Backup Battery (078-000-004)

This 3.7V 2600mAh (9.62Wh) lithium-ion cell is the backup battery for the RAID controller in Dell EMC Isilon NL410, S210, X200, and X400 storage nodes. It holds controller cache during a power loss event, giving the system time to flush write-pending data and shut down cleanly. Without a functional cell, the controller drops to write-through mode and cache protection is gone.

• NL410, S210, X200, X400 compatibility: These Isilon nodes share the same controller board architecture and use the same 3.7V cell with OEM part numbers 078-000-004, 415-0021-01, and 078-000-015-00. The BMS handshake and connector are identical across this generation of nodes.
• Bench tested on actual hardware: We ran this cell through charge, discharge, and BMS communication checks. The controller recognised the cell, initiated the learn cycle handshake, and reported battery status correctly through the management interface.
• Learn cycle initialisation after swap: After fitting this cell, trigger the battery learn cycle from the controller interface — on ONTAP use system controller battery show, on StorCLI use /cx bbu show. The controller stays in write-through mode until the learn cycle completes and recalibrates the backup window against the new cell's actual capacity.

RAID controller staying in write-through mode after battery swap

Fitting a new cell does not automatically return the controller to write-back mode. The controller must complete a full learn cycle — charge, discharge, and recharge — before it recalculates the backup window and re-enables write-back caching. This cycle typically takes 24 to 72 hours under normal system load. Until the cycle finishes, the controller intentionally holds write-through mode to protect data. Check cycle status with system controller battery show on ONTAP or StorCLI /cx bbu show on LSI-based controllers.

Management console reporting a battery error days after installation

Isilon controllers run scheduled battery self-assessments on a timed interval — not at boot and not immediately after a swap. If the first scheduled assessment runs before the learn cycle has fully completed, the controller logs a battery error or flags the backup window as unknown. This is a timing issue, not a cell fault. Wait for the learn cycle to finish, then check whether the error clears on the next scheduled assessment cycle. If the error persists after 72 hours and a completed learn cycle, verify cell voltage is at or above 3.6V with a multimeter before assuming a defective unit.