About this replacement
MelGeek Mojo60 — 3.8V Li-Polymer Replacement Battery (MLP5741112)
This 3.8V, 4100mAh lithium-polymer battery replaces the original MLP5741112 cell inside the MelGeek Mojo60 wireless mechanical keyboard. It restores the keyboard's wireless operation when the factory battery no longer holds charge across a workday. Dimensions are 113.10 × 40.70 × 5.80mm — confirm clearance inside the Mojo60 chassis before fitting.
- Mojo60 wireless platform: The Mojo60 runs its Bluetooth stack and RGB backlight from a single Li-Polymer cell. Both loads draw from the same rail, so a degraded cell hits usable capacity faster than voltage alone suggests — the BMS cuts power to protect the cell before the keyboard signals low battery.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the bench, confirmed BMS handshake, and verified the protection circuit trips correctly at low-voltage cutoff — no runaway draw during RGB-heavy use.
- RGB and Bluetooth draw management: On the Mojo60, running full RGB brightness alongside active Bluetooth polling pulls the cell voltage down faster than keyboard-only mode. Dropping backlight brightness when the keyboard is away from USB power extends usable time between charges noticeably.
Pairing lost after battery swap on the Mojo60
When the Mojo60 loses power completely during a battery swap, the Bluetooth pairing profile stored in RAM is wiped. The host device still shows the keyboard as paired, but the keyboard itself has no matching record. This causes a one-sided pairing state where the host waits and the keyboard never responds. Re-pair from scratch using the Mojo60's pairing key combination — do not rely on the host's "reconnect" prompt.
Keyboard connects but input lags or drops characters at low charge
As the Li-Polymer cell drops below roughly 3.5V, the Bluetooth radio receives less stable power and the polling interval widens. The result is dropped keystrokes or delayed character registration — not a firmware issue. This is a normal end-of-life voltage behaviour, not a defect in the new battery. If this symptom appears after fitting the replacement, check the cell is seated firmly and the connector is fully clicked into the PCB header.