Dell PowerEdge M620 RAID Controller Replacement Battery 3.7V 830mAh

Dell PowerEdge M620 / R320 / R420 / R520 — 3.7V Li-ion RAID Controller Cache Battery (7VJMH)

This 3.7V, 830mAh Li-ion cell replaces the backup battery on Dell PowerEdge RAID controllers fitted in M620, R320, R420, and R520 servers. It holds the controller's write cache during an unexpected power loss, preventing data corruption on in-flight write operations. OEM part numbers covered: 7VJMH, 07VJMH, 70K80, 070K80, T40JJ, H132V, and 37CT1.

• PowerEdge M620 / R-series compatibility: These servers share the same RAID controller battery footprint, connector pinout, and BMS handshake protocol. The controller validates cell voltage and thermistor response at boot — this cell passes both checks on the affected controller families.
• Bench tested on actual hardware: We ran this cell on a PowerEdge RAID controller and monitored BMS communication through the full initialisation sequence. The controller accepted the cell, began the learn cycle, and transitioned from write-through to write-back mode once the backup window was recalibrated.
• Post-installation learn cycle — RAID controller specific: After fitting the new cell, initiate the battery learn cycle from your controller management interface. On Broadcom/LSI controllers, run: StorCLI /cx bbu show. On ONTAP: system controller battery show. The controller holds write-through mode until the learn cycle finishes and sets a new backup window estimate against this cell — this is expected behaviour, not a fault.

RAID controller staying in write-through mode after battery swap

Write-through mode is the controller's default safe state whenever it cannot verify the backup window on the installed cell. Swapping the battery resets the recalibration — the controller does not inherit the previous cell's learn data. Until the learn cycle runs to completion (typically 24–72 hours under normal load), write-back mode stays locked out. Trigger the learn cycle manually from StorCLI or your RAID management interface rather than waiting for the scheduled auto-run.

Management console showing a battery error days after installation

The RAID controller does not run a full battery assessment at the moment of installation. The self-test runs on a timed interval — often 90 days by default — and that timer does not reset on swap unless you force it. If the console flags a battery error several days post-install, the assessment has run against a cell that has not yet completed its first full learn cycle. Force a new learn cycle from StorCLI (/cx bbu startLearn) and allow it to complete before reading the result.