Bea-fon C350 Replacement Battery 3.7V 700mAh Li-ion

Bea-fon C350 — 3.7V Li-ion Replacement Battery (C350)

This is a 3.7V 700mAh (2.59Wh) Li-ion replacement battery for the Bea-fon C350 mobile phone. It fits directly into the C350 and restores power to a phone that no longer holds a useful charge. The original cell degrades after repeated charge cycles — this replacement brings the phone back to full operation.

• Bea-fon C350 fit: The C350 uses a compact 3.7V single-cell pack at 40.15 × 48.90 × 4.80mm. This replacement matches that footprint and voltage rail exactly, so the phone's charge IC and BMS handshake proceed without fault codes.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the bench. The BMS engaged cutoff at the correct high and low voltage thresholds, and the charge IC accepted the cell without triggering an incompatibility fault on the first cycle.
• Fuel gauge recalibration on first use: On first use after fitting, run one full discharge down to automatic shutdown, then charge uninterrupted to 100%. The fuel gauge IC on the C350 was calibrated to the old cell's discharge curve — one complete cycle resets it against the new cell so percentage readings reflect actual remaining charge.

Why the C350 reports wrong battery percentage after a cell swap

The C350's fuel gauge IC builds its capacity model from the discharge curve of the cell it was last calibrated against. Swap in a new cell and the IC is still reading against the old, degraded curve. The result is percentage figures that jump, stall, or show full charge while the phone is actually near cutoff. One full discharge-charge cycle gives the IC enough data points to rebuild an accurate model against the new cell. Until that cycle completes, treat the percentage display as approximate.

Sudden shutdown at 20–30% on the replacement cell

This happens when the fuel gauge IC hasn't yet recalibrated and the phone hits the cell's real voltage floor before the display reaches 0%. A fresh Li-ion cell has a steeper voltage drop at low charge than an aged cell — the phone's cutoff threshold triggers earlier than the gauge expects. If the C350 shuts off abruptly at 20–30%, place it on charge immediately and run that first full calibration cycle. After recalibration, the gauge and the actual cell voltage floor align, and shutdowns at high percentage stop.