Mегафон CP10 Replacement Battery 3.7V 1200mAh Li-ion

Mегафон CP10 / TDM15 — 3.7V Li-ion Replacement Battery

This 3.7V 1200mAh Li-ion cell replaces the original battery in the Mегафон CP10 and TDM15 smartphones. It measures 53.00 × 34.00 × 5.70mm and matches the original connector orientation and BMS pinout. Capacity figure is taken directly from the product specification — 4.44Wh total energy.

• CP10 and TDM15 shared platform: Both models run the same 3.7V nominal voltage rail and use an identical physical footprint, which is why they share this cell. The connector tab spacing and BMS communication lines carry over between units without modification.
• Bench tested on actual hardware: We ran this cell through a full charge-discharge cycle on the CP10 platform. The BMS accepted the charge handshake cleanly, current draw at the charge IC peaked at the expected rate, and the protection circuit tripped correctly at the low-voltage cutoff threshold.
• Fuel gauge recalibration on first cycle: On first use after fitting this cell, disable any fast-charge option and run one complete discharge-to-charge cycle at standard rate. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging begins on an uncalibrated counter.

Sudden shutdown at 20–30% on the CP10 after a cell swap

This is a voltage cliff issue, not a capacity problem. Under peak load — modem transmit bursts, screen at full brightness — the new cell's internal resistance briefly drops terminal voltage below the protection threshold. The phone reads 25% state of charge but the cell cannot sustain the voltage under that instantaneous current draw. One full slow discharge-charge cycle tightens the fuel gauge IC calibration and reduces premature cutoff events. If shutdowns persist past three full cycles, check that the battery connector is fully seated — partial contact raises effective resistance at the tab.

OS showing wrong battery percentage after fitting the new cell

The CP10's fuel gauge IC stores a learned discharge curve from the previous cell. After a cell swap, that stored curve no longer matches the new cell's actual voltage-to-capacity relationship, so percentage readings drift or jump erratically. The fix is one complete discharge down to automatic shutdown followed by a full uninterrupted charge to 100%. That single cycle forces the coulomb counter to reset its reference points against the new cell. Do not interrupt the charge during this first cycle — a partial cycle leaves the curve partially corrected and the gauge stays inaccurate.