Rapoo MT750L Wireless Keyboard Compatible Battery 3.7V 800mAh

Rapoo MT750L / MT750 Pro — 3.7V Li-Polymer Replacement Battery (US613143N)

This 3.7V, 800mAh Li-Polymer battery replaces the internal rechargeable cell in the Rapoo MT750L and MT750 Pro wireless mouse. The MT750 series uses a built-in rechargeable pack rather than swappable AA or AAA cells, so when the original cell degrades, the mouse needs a direct cell replacement. Capacity and voltage match the factory spec exactly.

• MT750L and MT750 Pro shared cell: Both models use the same 3.7V single-cell Li-Polymer pack on the same charge rail, with the same connector footprint and BMS communication protocol — which is why one replacement covers both.
• Bench tested on actual hardware: We cycled this cell through charge and full-draw discharge on the MT750 platform. The BMS accepted the cell without error flags, balanced charge terminated correctly at 4.2V, and low-voltage cutoff triggered at the expected threshold without hard lockout.
• Li-Polymer cell handling during swap: The US613143N is a 5.20mm thin pouch cell — do not crease or bend the cell body during installation. A kinked pouch cell can develop an internal short that the BMS will not always catch at low charge levels.

Keyboard pairing lost after the MT750L battery goes flat

The MT750L stores its multi-device pairing table in volatile memory backed by the main cell. When the cell drops below the BMS cutoff and holds there for an extended period, that memory loses power entirely and the pairing data is cleared. Reconnecting the USB receiver alone will not restore the link — you need to hold the pairing button on the mouse until the LED cycles, then re-select the channel on the receiver side. After fitting a fresh cell, charge to at least 3.9V before attempting to re-pair.

Pointer stuttering and lag before the MT750 Pro shows a low-battery warning

Bluetooth polling rate on the MT750 Pro drops when the cell voltage sags below roughly 3.5V under load — this happens before the on-screen battery indicator flags low charge, because the indicator reads resting voltage, not loaded voltage. The result is intermittent cursor lag that looks like interference but is actually the radio throttling to stay within power budget. Charging the mouse resolves it immediately. If stuttering returns quickly after a full charge on the original cell, the cell has degraded and replacement is the correct fix.