About this replacement
Sonim XP3 Plus / XP3900 — 3.85V Li-Polymer Replacement Battery (BAT-02300-01S)
This 3.85V, 1400mAh Li-Polymer battery replaces part number BAT-02300-01S in the Sonim XP3 Plus and XP3900 rugged smartphones. It fits both models directly, restoring power to a device built for industrial and outdoor use. Capacity is 1400mAh (5.39Wh) — matching the factory specification.
- XP3 Plus and XP3900 compatibility: Both models share the same battery bay dimensions, connector pinout, and BMS handshake protocol. The same cell works across both variants without modification.
- Bench tested on actual hardware: We cycled this battery through charge and discharge on the XP3 platform. The BMS responded correctly to charge termination, and the fuel gauge IC accepted the cell without triggering a fault state.
- First-cycle fast charge protocol: On first use after installation, disable fast charging and run one complete discharge-charge cycle at standard current. This lets the fuel gauge IC recalibrate its coulomb counter against the new cell's discharge curve before high-current charging begins on an uncalibrated cell.
Sudden shutdown at 20–30% on the XP3 Plus after a cell swap
This happens because the fuel gauge IC is still mapped to the old cell's discharge curve. The new cell hits a voltage cliff — typically around 3.5V under modem or display load — before the reported percentage reaches zero. The phone shuts down to protect the cell, even though the gauge shows charge remaining. One full discharge-charge cycle at standard current resets the coulomb counter and brings the percentage readout back in line with actual cell voltage.
XP3 Plus not powering on after sitting in storage
Li-Polymer cells left discharged in storage can drop below 2.5V per cell, which triggers a BMS lockout — the battery stops responding entirely to protect against cell damage. The phone will not boot and may not show a charging indicator when you plug in. Connect to a wall charger rated at 5V and leave it for 20–30 minutes without pressing any buttons; the BMS recovery circuit needs sustained low-current input to exit lockout. If the device still shows no sign of life after that window, check the charger is delivering at least 5V 1A before drawing any other conclusions.