MyPhone BS-03 6200 Replacement Battery 3.7V 1200mAh

MyPhone 6200 — 3.7V Li-ion Replacement Battery (BS-03)

The BS-03 is a 3.7V Li-ion cell rated at 1200mAh (4.44Wh), built to the same footprint as the original MyPhone 6200 battery. It fits the 6200 directly — same connector, same physical dimensions at 62.18 × 38.14 × 4.50mm. Swap it in when the original cell no longer holds enough charge for calls, messaging, or basic app use.

• MyPhone 6200 fitment: The 6200 uses a compact 3.7V single-cell layout with a low-current BMS matched to a slim chassis. The BS-03 carries the same connector pinout and cell dimensions, so the BMS handshake completes without modification.
• Bench tested on actual hardware: We cycled the BS-03 through charge and discharge on the bench. The BMS held cutoff correctly at low-voltage limits and accepted charge current without tripping protection. Capacity measured within spec across test cycles.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging if your charger supports it, then run one complete discharge-to-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before reporting accurate percentages — skipping this step is the main cause of erratic percentage readings after a cell swap.

Why the MyPhone 6200 reports wrong battery percentage after a cell swap

The 6200's fuel gauge IC uses a coulomb counter calibrated against the discharge curve of the original cell. When a new cell goes in, the stored curve no longer matches the actual cell chemistry, so the IC misreads state of charge. You'll see the percentage jump, stall, or report full when the cell isn't. One full discharge-to-charge cycle forces the coulomb counter to re-learn the curve against the new cell. After that cycle, percentage reporting stabilises.

Sudden shutdown at 20–30% on the MyPhone 6200

This is a voltage cliff — not a capacity problem. Under modem transmit load or screen-on draw, the cell voltage drops faster than the fuel gauge expects, hitting the BMS undervoltage cutoff before the reported percentage reaches zero. It happens most often when the fuel gauge IC hasn't yet recalibrated to the new cell. Run one full discharge cycle and check whether the shutdowns continue. If they persist after calibration, confirm the charger is delivering a full charge termination voltage of 4.2V at the battery terminals.