Bea-fon C250 Replacement Battery 3.7V 900mAh Li-ion

Bea-fon C250 / Classic Line Series — 3.7V Li-ion Replacement Battery (C250)

This 3.7V, 900mAh Li-ion cell replaces the original battery in the Bea-fon C250 and Classic Line C250/C260 handsets. These are basic mobile phones built for straightforward daily use, and the battery is the first component to degrade over time. Capacity is rated at 3.33Wh, matching the original cell specification.

• C250 and Classic Line compatibility: The C250, Classic Line C250, and Classic Line C260 share the same battery bay dimensions and connector pinout — 46.47 × 39.79 × 5.33mm — so one cell fits all three without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the C250 platform. The BMS handshake completed cleanly and the charge IC accepted the cell without fault flags on the first cycle.
• First-cycle fuel gauge reset: After fitting this battery, run one full discharge down to automatic shutdown, then charge uninterrupted to 100% before normal use. This gives the fuel gauge IC one complete reference cycle against the new cell's discharge curve.

Why the C250 shows the wrong battery percentage after a cell swap

The Bea-fon C250 uses a fuel gauge IC that builds its state-of-charge model against the discharge curve of the cell it learned on. When you fit a new cell, the IC still references the old curve, so its percentage readout drifts immediately. The error is most visible between 40% and 15%, where the old cell had a steeper voltage drop than the new one. One full discharge-charge cycle gives the IC enough data to recalibrate. After that cycle, the percentage display tracks accurately across the full charge range.

Sudden shutdown with battery percentage still showing 20–30%

This happens when the cell voltage drops sharply under load — a call, backlight activation, or network search draws enough current to push cell voltage below the BMS cutoff threshold even though the resting charge appears sufficient. On the C250, the modem radio and display together can spike current draw well above the idle rate. The fuel gauge IC, still working from an uncalibrated curve, reports 20–30% remaining right up until the voltage cliff. Run the first-cycle calibration discharge described above; if shutdowns continue after calibration, measure resting cell voltage — it should hold above 3.6V after a full charge.