Clarisonic Mia 2 Replacement Battery 2.4V 700mAh Ni-MH

Clarisonic Mia 2 — 2.4V Ni-MH Replacement Battery (AA-2-900-PB3)

This is a 2.4V, 700mAh Ni-MH replacement battery for the Clarisonic Mia 2 sonic facial cleansing brush. It replaces OEM part AA-2-900-PB3 and fits directly into the Mia 2 housing. If your device no longer holds a charge or powers down mid-use, this battery is the correct replacement.

• Mia 2 platform fit: The Mia 2 runs a single-cell Ni-MH pack at 2.4V to drive the oscillating brush motor. This cell matches that voltage rail and the physical dimensions — 44.35 x 20.66 x 10.70mm — required by the internal housing cavity.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the Mia 2 platform. The BMS accepted the cell without fault codes, and the motor reached full oscillation speed within normal spin-up time.
• Post-wash charging precaution: Dry the charging port fully before docking after use near water. Moisture bridging the contacts can trigger a protection fault that reads as a dead battery rather than a charging error — wiping and air-drying the base for two minutes before connecting clears this.

Battery fade from daily top-up charging on the Mia 2

Ni-MH cells develop gauge drift when regularly charged in short top-off cycles without a full discharge. The Mia 2 has no active fuel gauge to correct this — it reads estimated state-of-charge based on voltage, not actual capacity. Over months of partial charging, the cell's reported full-charge voltage and its real capacity drift apart. The device then powers down at what appears to be a partial charge because the voltage has sagged below the motor's threshold, even though the indicator hasn't triggered yet.

Mia 2 motor losing speed before the battery indicator activates

This happens when the Ni-MH cell can no longer sustain voltage under the motor's oscillation load. A degraded cell may read 2.4V at rest but drop below 2.0V the moment the motor draws current — enough to slow the brush head without triggering the low-battery indicator. The indicator threshold is set for resting voltage, not loaded voltage. Replacing the cell resolves this; after fitting the new battery, run one full charge cycle before first use to let the cell stabilise at rated capacity.