Razer RC03-001201 Replacement Battery 3.7V 900mAh

Razer Mamba RC03 — 3.7V Li-ion Replacement Battery (FT703437PP)

This 3.7V, 900mAh Li-ion cell replaces the internal battery in the Razer Mamba RC03 wireless mouse (RC03-001201). It fits directly into the battery compartment and reconnects to the original charging circuit. If your Mamba no longer holds a charge between sessions, this is the cell to swap.

• Mamba RC03 fit: The RC03-001201 uses a single flat Li-ion cell on a 3.7V rail with a proprietary connector. This cell matches the OEM footprint (43.01 × 35.24 × 8.58mm), connector pinout, and BMS handshake required by Razer's charging dock circuit.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the RC03 platform. The BMS accepted the cell without error flags, and the charge LED on the dock behaved identically to an OEM unit.
• RGB and polling draw on the Mamba RC03: The Mamba RC03 runs Chroma RGB and a high-frequency polling loop simultaneously. Keep Chroma brightness below 50% in Synapse when you need longer sessions — RGB at full brightness is the single largest drain on this 900mAh cell.

Mamba RC03 not reconnecting after battery swap

After a full power loss — which happens when a dead cell is removed — the RC03's onboard pairing state can reset. The mouse may not reconnect to the USB receiver automatically. Unplug the USB receiver, wait ten seconds, replug it, then hold the pairing button on the underside of the mouse until the LED blinks. The receiver re-establishes the link within a few seconds at that point.

Pointer stuttering or lag before the low-battery indicator appears

The Mamba RC03's Bluetooth polling rate steps down when cell voltage sags below roughly 3.5V, even before the on-screen battery warning triggers. This shows up as micro-lag or skipped cursor movement under fast sweeps. It is not a sensor fault — it is the firmware conserving power at end of cell life. Replacing the cell and charging fully to 4.2V resolves the stutter immediately.