Dell DGK85 RAID Controller Compatible Battery 3.7V 2500mAh

Dell Controller Card DGK85 — 3.7V Li-ion Replacement Battery (078-000-136-04)

This 3.7V 2500mAh (9.25Wh) Li-ion cell replaces the backup battery on the Dell Controller Card DGK85 and Calypso I/O Controller Card DGK85. It maintains cache contents during a power failure so in-flight write data is not lost before the controller can flush to disk. OEM part number 078-000-136-04.

• DGK85 and Calypso I/O Controller Card fit: Both cards share the same 3.7V single-cell architecture, connector footprint, and BMS handshake protocol, which is why one cell covers both variants. The controller negotiates charge termination and backup window calculation directly with the cell's BMS over the same interface on each card.
• Bench tested on actual hardware: We cycled this cell through full charge, discharge, and BMS handshake verification on the DGK85 platform. The controller accepted the cell, initiated charge without fault, and the BMS reported state-of-charge correctly to the management interface.
• Learn cycle initiation after swap: After fitting this cell, trigger the battery learn cycle from your controller management interface — ONTAP: system controller battery show; StorCLI: StorCLI /cx bbu show. The controller holds in write-through mode and will not recalculate the backup window until the learn cycle runs to completion against the new cell's actual capacity.

RAID controller staying in write-through mode after battery swap

Installing a new cell does not automatically return the controller to write-back mode. The controller must complete a full learn cycle — a controlled discharge and recharge — before it can recalculate how long the new cell can hold cache during an outage. Until that number is confirmed, the controller stays in write-through mode as a precaution. On ONTAP, monitor progress with system controller battery show; on Broadcom/LSI controllers, use StorCLI /cx bbu show. The cycle typically takes 24–72 hours under normal load before write-back mode is restored.

Management console reporting a battery error days after installation

The controller does not run a full battery assessment at boot — it runs one on a timed schedule, often 24 to 90 days after the last recorded test. If the console flags a battery error shortly after a swap, the scheduled self-test has likely not yet run against the new cell, so the stored result still reflects the degraded old battery. Wait for the scheduled assessment to complete, or manually trigger a learn cycle to force an immediate recalibration. Once the cycle finishes, the error clears and the console updates the backup window estimate based on the current cell voltage, which should read 3.6–3.7V at rest after a full charge.