AC50BOX GSmart Mika M2 Replacement Battery 3.7V 2000mAh

GSmart Mika M2 — 3.7V Li-ion Replacement Battery (AC50BOX)

This 3.7V, 2000mAh Li-ion battery replaces the AC50BOX cell in the GSmart Mika M2 smartphone. It fits the original battery slot with the same 78.30 x 56.08 x 4.20 mm footprint. Use the capacity figure from the product data — 2000mAh — as the reference for this cell.

• Mika M2 fit: The Mika M2 uses a single-cell 3.7V nominal Li-ion pack with a connector pinout and BMS handshake specific to this chassis. Swapping to any cell outside the AC50BOX spec risks a BMS rejection flag that prevents charging entirely.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the Mika M2 platform. The BMS accepted charge on the first cycle, protection circuits tripped at the correct cutoff voltages, and the fuel gauge IC began tracking the new discharge curve without manual reset.
• Fuel gauge recalibration on first use: After fitting this cell, disable any fast-charge mode and run one full discharge-to-charge cycle before normal use. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before high-current charging pushes current into an uncalibrated cell.

Why the Mika M2 reports wrong battery percentage after a cell swap

The Mika M2 uses a fuel gauge IC that stores a learned discharge curve from the original cell. When a new cell goes in, that stored curve no longer matches the actual cell chemistry. The IC continues reading voltage against the old map, so it reports percentages that are off by 10–20%. One full discharge cycle — run the phone down until it shuts off, then charge uninterrupted to 100% — forces the coulomb counter to rebuild the curve against the new cell. After that single cycle, percentage accuracy returns to normal.

Sudden shutdown at 20–30% on the Mika M2 after replacement

This is a voltage cliff failure. The cell's terminal voltage drops sharply under modem or screen load before the fuel gauge IC registers a low-battery warning. The phone shuts down to protect the cell even though the percentage display still reads mid-range. It happens most often on the first few cycles while the fuel gauge recalibrates. Run two full discharge-charge cycles and confirm the cell resting voltage reads at least 3.75V after a full charge before resuming normal use.