BenQ-Siemens P50 Compatible Battery 3.7V 2600mAh 23.20115.102

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

This 3.7V, 2600mAh lithium-polymer battery replaces part number 23.20115.102 in the BenQ-Siemens P50 smartphone. It fits the P50 directly and restores power capacity lost to cell degradation over repeated charge cycles. Dimensions are 68.38 × 44.95 × 12.50mm — confirm clearance before fitting.

• P50 cell fitment: The P50 uses a single flat Li-Polymer cell with a low-profile connector. The BMS on this phone monitors cell voltage closely — a cell with degraded internal resistance triggers premature low-battery warnings even when nominal capacity looks fine on a charger.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a P50 chassis. The BMS accepted the new cell without rejection, and the protection circuit tripped correctly at the low-voltage threshold with no false cutoffs during mid-load draw.
• Fuel gauge recalibration on first use: On first use after installation, run one full discharge to automatic shutdown and then charge uninterrupted to 100% before using the phone normally. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before trusting percentage readouts.

Why the P50 reports wrong battery percentage after a cell swap

The P50's fuel gauge IC stores a learned discharge curve from the previous cell. When a new cell goes in, that stored curve no longer matches the actual voltage-to-capacity relationship of the replacement. The gauge reads voltage and converts it using the old map, so it can show 40% when the cell is nearly flat — or 100% before the cell is actually full. One complete discharge-to-shutdown followed by a full uninterrupted charge forces the IC to recalibrate its internal model against real cell behaviour.

Sudden shutdown at 20–30% on the P50 after replacement

This is a voltage cliff — not a capacity problem. When the P50's modem or display draws a short high-current spike, the cell voltage dips sharply under load. If the BMS sees that dip cross its cutoff threshold, it shuts the phone down even though the gauge still shows charge remaining. It happens most often when the cell is cold or the fuel gauge IC has not yet recalibrated to the new cell's internal resistance profile. Complete one full recalibration cycle first; if shutdowns continue, check that the cell connector is fully seated and measure resting cell voltage — it should read above 3.7V after a full charge.