URC UN-MX6000 Replacement Battery 3.7V 5200mAh Li-ion

URC UN-MX6000 / MX-6000 — 3.7V Li-ion Replacement Battery (BTBL4800SL)

This is a 3.7V Li-ion rechargeable battery rated at 5200mAh (19.24Wh), built as a direct replacement for the URC UN-MX6000, MX-6000, and UE-MX6000 universal remote controls. It replaces OEM part numbers BTBL4800SL and BATMX6000. If your original battery no longer holds a charge or fails to power the remote, this cell restores full operation.

• UN-MX6000 / MX-6000 / UE-MX6000 fit: All three model variants share the same battery bay dimensions, connector pinout, and 3.7V nominal voltage rail, which is why a single cell covers the range. The BMS handshake is identical across the series.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the MX-6000 platform. The BMS accepted the charge curve without fault, and IR LED output stayed consistent across the full discharge range down to the low-voltage cutoff.
• Single-cell remote charging: Because this remote runs one rechargeable Li-ion cell rather than disposable alkalines, avoid letting it drain completely before recharging. Li-ion cells in low-draw devices like remotes are prone to over-discharge if left unused for months — the BMS may lock the cell out entirely at that point.

Why the MX-6000 stops responding from normal operating distance

The IR LEDs in the MX-6000 require consistent voltage to fire at full output. As the Li-ion cell degrades, terminal voltage sags under the brief high-current pulse each IR burst demands. The remote may still power on and display correctly, but the IR signal weakens enough that the receiver in your TV or receiver can't pick it up reliably past a metre or two. Replacing the battery restores the voltage headroom the IR circuit needs to transmit at rated power.

Remote completely unresponsive after new battery install

This almost always comes down to connector orientation. The BTBL4800SL uses a keyed JST-style connector, but the polarity labels inside the battery bay on some MX-6000 units are small and easy to miss. If the remote shows no signs of life at all after install, remove the battery and check that the red wire aligns with the positive terminal marked on the board. Reconnect firmly until you feel the connector seat, then hold the power button for three seconds to wake the system from its off state.