BenQ-Siemens P50 Compatible Battery 3.7V 1800mAh Li-Polymer

BenQ-Siemens P50 — 3.7V Li-Polymer Replacement Battery (23.20115.102)

This 3.7V, 1800mAh lithium-polymer battery replaces the original cell in the BenQ-Siemens P50 smartphone. It carries OEM part number 23.20115.102 and matches the original dimensions at 53.11 × 34.07 × 5.31mm. If the P50 no longer holds a charge or shuts down unexpectedly, this is the direct replacement cell.

• P50 fitment: The P50 uses a slim Li-Polymer pouch format locked to a specific footprint and connector orientation. This cell matches that footprint exactly — same connector pinout, same BMS voltage thresholds the phone's charge IC expects at 3.7V nominal.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the P50 platform. The BMS communicated correctly with the phone's charge IC, cutoff triggered at the correct low-voltage threshold, and charge termination completed without fault flags.
• Fuel gauge recalibration on first use: On first installation, run one complete discharge-to-charge cycle with fast charging disabled. This lets the fuel gauge IC map the new cell's discharge curve before normal use — skipping this step causes percentage readouts to drift or jump during the first few days.

Sudden shutdown at 20–30% on the P50 after a cell swap

This is a voltage-cliff issue, not a capacity issue. When the P50's modem or display draws a burst of current, a new uncalibrated cell can sag below the shutdown threshold momentarily — even when the fuel gauge still shows charge remaining. The phone's power management IC reads the instantaneous voltage, not the stored percentage, and cuts power to protect the cell. One full discharge-charge cycle with the screen at normal brightness recalibrates the coulomb counter and clears this behaviour in most cases.

P50 showing incorrect battery percentage after replacement

The fuel gauge IC on the P50 builds its charge model from historical discharge data stored against the old cell. After a cell swap, that learned curve no longer matches the new cell's actual voltage profile, so the percentage readout lags or jumps. Discharge the phone until it shuts off automatically, then charge uninterrupted to 100% without removing the cable early. After one full cycle completed this way, the IC resets its reference points and percentage reporting stabilises. If jumping persists after two cycles, check that the battery connector is fully seated — a loose pin causes intermittent voltage reads that confuse the coulomb counter.