MyPhone HAMMER AXE Replacement Battery BW-02H 3.7V 3200mAh

MyPhone HAMMER AXE / HAMMER AXE LTE — 3.7V Li-Polymer Replacement Battery (BW-02H)

This is a 3.7V, 3200mAh Li-Polymer replacement battery for the MyPhone HAMMER AXE and HAMMER AXE LTE rugged smartphones. It matches OEM part number BW-02H and fits both variants of the HAMMER AXE line. Capacity is 11.84Wh — identical to the factory specification.

• HAMMER AXE and HAMMER AXE LTE compatibility: Both variants share the same battery bay geometry, connector pinout, and BMS handshake protocol — one cell fits both. The LTE model draws higher current from the radio modem, and this cell's discharge curve handles that load without voltage sag triggering early shutdowns.
• Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on the HAMMER AXE platform. The BMS accepted charge normally, protection thresholds engaged at the correct cutoff voltages, and the fuel gauge IC tracked state-of-charge without erratic jumps after the second full cycle.
• Fuel gauge recalibration on first use: After installation, disable fast charging and complete one full discharge-charge cycle at standard current. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging begins — skipping this step is the main cause of erratic percentage readings in the first week.

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

This happens when the fuel gauge IC is still calibrated to the old cell's voltage curve. The new cell hits a steeper voltage cliff under modem or screen load, and the OS reads 25% right up until the cell can no longer sustain voltage — then the phone cuts off instantly. The fix is one full discharge to auto-shutoff followed by a complete charge to 100% at standard (non-fast) current. After that cycle, the coulomb counter recalibrates and the reported percentage tracks actual cell state accurately.

Device not powering on after the replacement battery sat in storage

Li-Polymer cells self-discharge in storage, and if the cell drops below approximately 2.5V, the BMS locks out to prevent damage — the phone will show nothing when you press the power button. Connect the device to a wall charger (not a PC USB port, which may not supply enough current) and leave it for 15–20 minutes before attempting to power on. The charge IC needs to trickle current into the cell long enough to bring it above the BMS recovery threshold, typically around 2.9V, before normal charging resumes.