Swisstone BBM 625 Replacement Battery 3.7V 900mAh Li-ion

Swisstone BBM 625 — 3.7V Li-ion Replacement Battery (RCB03S02)

This is a 3.7V, 900mAh (3.33Wh) Li-ion replacement battery for the Swisstone BBM 625 mobile phone. It uses OEM part number RCB03S02 and fits directly into the BBM 625 battery bay. If your phone is shutting down early, losing charge fast, or not holding power at all, this cell replaces the degraded original.

• BBM 625 fit: The BBM 625 uses a compact 53.00 × 34.00 × 4.30mm cell at 3.7V. This replacement matches that form factor and voltage rail exactly, so the connector seats correctly and the phone's charge IC sees the expected cell impedance.
• Bench tested on actual hardware: We cycled this cell through a full discharge and charge sequence, confirmed BMS communication with the charge IC, and verified the protection circuit trips correctly at voltage floor — no runaway, no false cutoff mid-cycle.
• Fuel gauge recalibration on first use: After fitting this cell, run one complete discharge from 100% to automatic shutdown, then charge uninterrupted to 100% before enabling any fast-charge option. This gives the fuel gauge IC one full reference cycle against the new cell's discharge curve.

Why the BBM 625 reports wrong battery percentage after a cell swap

The BBM 625 fuel gauge IC builds its percentage model from a learned discharge curve stored against the original cell. When you install a new cell, that stored curve no longer matches actual cell behaviour. The IC reads voltage and maps it to the old curve, so it shows inaccurate percentages — often jumping or freezing at certain points. One complete uninterrupted discharge-charge cycle forces the IC to rewrite its reference data against the new cell.

Sudden shutdown at 20–30% on the replacement cell

This happens when the cell voltage drops sharply under load — a voltage cliff — before the fuel gauge registers critically low charge. On the BBM 625, the modem drawing current during a call or data event can pull enough current to cause the cell voltage to sag below the BMS cutoff threshold even when the gauge still reads 20–30%. A degraded original cell develops this cliff over time, but a new cell can show it briefly if the fuel gauge IC hasn't recalibrated yet. Run the full recalibration cycle first; if shutdowns persist after that, check that resting cell voltage after a full charge reads at or above 4.1V.