Panasonic KX-TU110 Compatible Battery 3.7V 1200mAh 523450AR

Panasonic KX-TU110 Series — 3.7V Li-ion Replacement Battery (523450AR)

This 3.7V, 1200mAh Li-ion cell replaces the original 523450AR battery in the Panasonic KX-TU110 mobile phone. It also fits the KX-TU110 EXB, KX-TU110 EXC, and KX-TU110 EXV variants. All share the same connector pinout and BMS handshake, so one cell covers the full KX-TU110 range.

• KX-TU110 range compatibility: The EXB, EXC, and EXV variants run the same 3.7V voltage rail and use an identical dock connector with the same BMS communication lines. One replacement cell works across all four models without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on KX-TU110 hardware. The BMS accepted the cell on first connection, current limiting kicked in correctly at full charge, and protection tripped cleanly at the low-voltage cutoff threshold.
• Fuel gauge recalibration on first use: After fitting the new cell, disable any fast-charge mode and run one full discharge-charge cycle before normal use. This gives the phone's fuel gauge IC time to map the new cell's actual discharge curve. Without it, the percentage readout can lag or jump during the first few sessions.

Why the KX-TU110 reports wrong battery percentage after a cell swap

The KX-TU110 uses a coulomb counter in the fuel gauge IC to track charge state. That counter was calibrated against the original cell's specific discharge curve. A new cell has a slightly different internal resistance profile, so the stored calibration data no longer matches reality. The phone reads a voltage point, maps it to the old curve, and displays a percentage that does not reflect actual remaining charge. One slow full discharge followed by a full charge resets the calibration data to the new cell's curve.

Sudden shutdown at 20–30% on the KX-TU110

This happens when the cell voltage drops sharply under the load spike from the radio transmitter or screen backlight — a voltage cliff the fuel gauge IC does not predict in advance. The BMS reads the sudden voltage sag as a under-voltage condition and cuts power before the displayed percentage reaches zero. It is not a faulty cell; it means the fuel gauge still needs calibration. Run a full slow discharge cycle to the auto-off point, charge fully, and the shutdown threshold should stabilise at or below 5%.