Bea-fon S10 Replacement Battery 3.7V 1000mAh Li-ion

Bea-fon S10 — 3.7V Li-ion Replacement Battery (S10)

This is a 3.7V, 1000mAh Li-ion replacement battery for the Bea-fon S10 mobile phone. It slots directly into the S10's battery bay and restores power to a phone that won't hold charge or won't switch on at all. Capacity listed is 1000mAh (3.7Wh) — matching the original cell specification.

• Bea-fon S10 fitment: The S10 uses a compact 53.70 × 36.85 × 5.30mm cell at 3.7V. This replacement matches those physical and electrical specs so the battery bay closes correctly and the charge IC sees the expected voltage rail on first boot.
• Bench tested on actual hardware: We ran this cell through a full charge-discharge cycle on the S10 platform. The BMS accepted charge from the phone's onboard charge IC without fault codes, and voltage held steady across a screen-on load cycle.
• Fuel gauge recalibration on first use: On first use after installation, run one complete discharge-to-charge cycle before relying on the percentage indicator. The S10's fuel gauge IC is calibrated to the old cell's discharge curve — one full cycle lets it remap against the new cell and report accurately.

Why the S10 reports wrong battery percentage after a cell swap

The S10 tracks charge state using a fuel gauge IC that builds a model of the cell's discharge curve over time. When you swap to a new cell, that learned curve no longer matches the physical battery in the phone. The IC keeps using the old model, so it reports percentages that can be 15–25% off. One full discharge below 10% and a charge to 100% resets the coulomb counter and forces the IC to start learning the new cell's actual curve.

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 reaches 0%. The S10's modem and display draw enough current to pull the cell below the BMS cutoff threshold while the gauge still shows charge remaining. It is not a faulty battery — it is the fuel gauge IC reading from an uncalibrated curve. Run two full discharge-charge cycles and the shutdowns will move progressively closer to 0%. If they persist past three cycles, check the resting voltage sits above 3.6V when the phone shows 30%.