Microsemi 2294600-R SmartRAID Compatible Battery 5.4V 35F

Microsemi SmartRAID 3154-8i16e / ASR-3101-4i — 5.4V HPC Supercapacitor Replacement Battery (ASCM 35F)

This is a 5.4V, 35F HPC supercapacitor (ASCM 35F) for the Microsemi SmartRAID 3154-8i16e (2294600-R) and SmartRAID ASR-3101-4i SAS controller. It sits on the controller board and holds charge to flush the write cache to non-volatile storage during an unexpected power loss. Capacity is 35F (0.19Wh) — enough to complete a controlled cache destage before the controller shuts down.

• SmartRAID 3154-8i16e and ASR-3101-4i compatibility: Both controllers share the same ASCM 35F supercapacitor footprint, connector pinout, and BMS handshake protocol. Swapping between these two models uses the same cell — no firmware flag or recalibration differs between them at the hardware level.
• Bench tested on actual hardware: We cycled this supercapacitor through charge and discharge on a SmartRAID controller bench rig. The BMS accepted the cell without error, completed a full charge cycle, and reported healthy status in the controller management interface.
• Supercapacitor swap procedure on SmartRAID: Replace this cell with the host server powered on and the controller active. Removing the supercapacitor while the controller is offline leaves the write cache unprotected — if power is lost during that window, any dirty cache data is gone. Swap with the system live to maintain continuous cache protection.

Why the SmartRAID controller forces write-through mode after a capacitor swap

After installing a new supercapacitor, the SmartRAID controller automatically drops to write-through caching until it verifies the cell can hold sufficient charge to complete a cache destage. This is a deliberate protection state — not a fault. The controller runs an internal capacitor learn cycle, which charges the cell to rated voltage and confirms the stored energy meets the minimum threshold. Once the learn cycle passes, write-back caching re-enables automatically. No user action is needed beyond confirming the cell is seated correctly and the controller status clears in the management utility.

Controller reporting "Capacitor Pack Missing" after confirmed installation

This error appears when the supercapacitor connector is not fully seated — the BMS handshake line goes open and the controller logs the cell as absent. Re-seat the connector until it clicks, then check the controller status in the RAID management utility. If the error persists, measure voltage across the cell terminals: a new ASCM 35F shipped at storage voltage may read as low as 2.5V before the controller charges it to the 5.4V operating level. Give the controller 15–20 minutes to complete the initial charge before re-checking status.