HQ-50S Samsung Galaxy A02 Replacement Battery 3.85V 4900mAh

Samsung Galaxy A02 — 3.85V Li-Polymer Replacement Battery (HQ-50S)

This is the HQ-50S lithium-polymer cell for the Samsung Galaxy A02 (SM-A022F, SM-A022M/DS and related variants). It fits the 2021 A02 lineup where the original cell has degraded and can no longer hold a charge. Capacity is 4900mAh at 3.85V nominal, matching the OEM specification.

• SM-A022 variant coverage: The SM-A022F, SM-A022M/DS and associated regional variants all share the same battery bay geometry, connector pinout, and BMS handshake protocol — one cell fits the full A02 family without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on SM-A022F hardware. The BMS accepted the cell on first connection, voltage sat at 3.85V nominal under load, and charge termination triggered cleanly at full capacity with no fault codes.
• Fuel gauge recalibration tip: On first use after installation, disable fast charging and run one full discharge-to-charge cycle. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before high-current charging begins on an uncalibrated cell.

Sudden shutdown at 20–30% on the A02 after a cell swap

This happens because the fuel gauge IC on the A02 is still reading the discharge curve of the old, degraded cell. When the new cell hits a voltage point the gauge hasn't mapped yet, the phone interprets it as a critical low-voltage event and cuts power. The fix is a full calibration cycle — run the phone down to automatic shutdown, then charge uninterrupted to 100% with fast charging off. After one complete cycle, the coulomb counter resets and the percentage display stabilises.

USB fast charge not triggering after replacement

On the first charge cycle after fitting a new HQ-50S, the A02's charge IC sometimes falls back to standard 5V charging rather than negotiating the higher-current profile. This occurs because the BMS on a fresh cell reports a high internal impedance state, which causes the charge IC to throttle back as a precaution. Let the first charge complete fully on a standard charger without interruption. On the second cycle, fast charging typically re-negotiates correctly once the BMS has logged an initial full cycle.