Apple PowerBook G4 RAID Controller Replacement Battery 820-1814-A

Apple PowerBook G4 RAID Controller — 3.7V Li-Polymer Replacement Battery (820-1814-A)

This 3.7V, 180mAh Li-Polymer cell replaces the backup battery on the Apple PowerBook G4 RAID controller module. It fits the controller board used across PowerBook G4 models including A1107 17", A1106, and A1138. The battery sustains RAID controller cache during power loss, protecting write-back operations and data integrity.

• Controller board compatibility (820-1814-A / 820-1819-A / 820-1824-A): These three OEM part numbers share the same 3.7V Li-Polymer cell footprint, connector pinout, and BMS charge profile. All three boards use the same physical cell at 31.55 × 20.56 × 3.00mm.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the RAID controller board. The BMS accepted the cell without fault flags, held float charge at 4.2V, and reported state-of-charge correctly through the controller interface.
• Post-install learn cycle on the RAID controller: After swapping this cell, the controller will default to write-through mode until its learn cycle completes. Trigger it manually from your management interface — on ONTAP use system controller battery show. The backup window estimate recalibrates against the new cell over the first full cycle.

RAID controller staying in write-through mode after battery swap

The controller does not automatically switch back to write-back mode when a new battery is installed. It waits for the learn cycle to complete and verify the backup window against the new cell's actual capacity. Until that cycle finishes, write performance drops because the controller treats cache as unprotected. Kick off the learn cycle manually — on Broadcom/LSI controllers, run StorCLI /cx bbu startlearning; this typically completes within 24–48 hours under normal load.

Management console still showing a battery error two days after installation

The controller's battery health assessment does not run at boot — it runs on a scheduled interval, often 24 to 90 days depending on firmware. A swap mid-cycle does not reset the timer or trigger an immediate reassessment. The error clears once the next scheduled self-test runs and the cell passes. To force an early assessment on ONTAP, run system controller battery check — confirm the cell voltage reads above 3.5V before running it.