Nintendo Game Boy Micro OXY-003 Replacement Battery 3.7V 460mAh

Nintendo Game Boy Micro — 3.7V Li-Polymer Replacement Battery (OXY-003)

This is a 3.7V, 460mAh Li-Polymer cell that fits the Nintendo Game Boy Micro (OXY-001). It replaces the original OXY-003 pack when the console no longer holds a usable charge. The battery slots into the rear compartment and connects via the same three-pin contact the OXY-001 board expects.

• OXY-001 compatibility: The Game Boy Micro uses a single-cell Li-Polymer pack at 3.7V nominal. The OXY-003 and GPNT-02 part numbers both refer to this same form factor — same footprint, same connector, same BMS handshake the charge IC on the OXY-001 mainboard requires.
• Bench tested on actual hardware: We ran this cell in an OXY-001 unit and confirmed the charge IC accepted the new cell without fault codes. The BMS engaged protection at voltage floor as expected, and charge current tapered correctly through the constant-voltage phase.
• Fuel gauge calibration after install: After fitting this cell, run one full play session to automatic cutoff — do not interrupt it. The OXY-001's fuel gauge IC sets its empty reference point against the first complete discharge of the new cell. Skip this step and the battery indicator will read inaccurately from day one.

Why the Game Boy Micro shuts off before the battery indicator hits empty

The OXY-001 uses a simple fuel gauge that tracks remaining capacity by voltage curve, not coulomb counting. Aged cells develop a steeper voltage drop at low charge, so the BMS hits its cutoff floor while the indicator still shows one bar. A new cell has a flatter discharge curve — the gauge will read closer to true empty once calibrated. Run that first full discharge cycle and the shutdown point will align with the indicator.

Battery percentage jumping around after fitting a replacement cell

This happens because the fuel gauge IC stored the discharge curve of the original cell in its reference memory. The new cell's voltage profile doesn't match, so the gauge miscalculates state of charge and the percentage jumps non-linearly. The fix is a forced recalibration: drain the console completely to automatic shutoff, then charge uninterrupted to full. After one full cycle the gauge resets its reference to the new cell. If jumping persists after two cycles, check that the battery contacts on the OXY-001 board are clean and seating flush — a dirty contact causes intermittent voltage reads that look identical to a gauge calibration fault.