HP Agilent P1218-60002 RAID Battery 3.8V 3000mAh

HP Agilent P1218-60002 PCI-X Remote Control Card — 3.8V Li-Polymer Replacement Battery (5065-2756)

This 3.8V 3000mAh (11.4Wh) Li-Polymer cell replaces the backup battery module on the Agilent P1218-60002 PCI-X Remote Control Card. It maintains cached write data and system configuration during unexpected power loss. Without a functional cell, the controller falls back to write-through mode and cache protection is lost.

• P1218-60002 cache backup module: This card uses the backup battery to sustain DRAM cache content during a power event. The BMS monitors cell voltage and communicates charge state to the controller firmware — the controller only enables write-back caching once the battery passes its internal threshold check. A degraded cell fails that check and keeps write-back permanently suppressed.
• Bench tested on actual hardware: We cycled this cell through charge, hold, and simulated power-loss discharge on a RAID controller bench rig. The BMS accepted the cell without error flags, completed the initial learn cycle, and the controller transitioned from write-through to write-back mode after the backup window was recalculated.
• Post-swap controller initialisation: After fitting this cell, trigger a battery learn cycle manually from the management interface — StorCLI: /cx bbu start learn, ONTAP: system controller battery show. The controller will not recalculate its backup window estimate until the learn cycle completes. This process typically runs over one to three full charge and discharge passes under normal system load.

RAID controller staying in write-through mode after battery swap

Fitting a new cell does not automatically restore write-back caching. The controller firmware holds write-through mode until it receives a confirmed backup window estimate from the BMS — and that figure only updates after a full learn cycle. Until the cycle completes, the controller treats the battery as unqualified regardless of cell voltage. Initiate the learn cycle via StorCLI or your management console; the controller will switch to write-back once the backup window meets its minimum threshold, typically above 3.5V resting and a calculated hold time sufficient for graceful shutdown.

Management console showing a battery fault days after installation

This is a scheduled self-test result, not a boot-time detection — the controller runs its battery assessment on a timed interval, often 24 to 72 hours after the last completed cycle. If the learn cycle was still in progress when that assessment fired, the controller logs a fault because the backup window estimate was incomplete. Re-run the learn cycle from the management interface and allow it to finish without interruption. Once the cycle completes, the next scheduled assessment should clear the fault and log a passing result.