Swisscom XPA v1405 Replacement Battery 3.7V 1250mAh

Swisscom XPA v1405 — 3.7V Li-Polymer Replacement Battery (BERR160)

This is a 3.7V, 1250mAh Li-Polymer battery for the Swisscom XPA v1405 smartphone. It replaces OEM part numbers BERR160 and 35H00068-01M. The cell fits the original battery bay and connects to the same charging circuit without modification.

• XPA v1405 fitment: The v1405 uses a slim Li-Polymer cell at 64.58 × 41.71 × 5.94mm. The BMS communicates charge state over a dedicated third contact line — any replacement must match this pinout exactly or the charge IC will refuse to initiate a charge cycle.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the v1405 platform. The BMS accepted the handshake on the first connection, charge IC ramped normally from trickle to CC phase, and the fuel gauge registered capacity without manual reset.
• First-cycle recalibration on the v1405: After fitting, disable fast charging in the device settings and run one complete discharge-to-charge cycle at standard rate. This lets the fuel gauge IC map the new cell's discharge curve before fast-charge current is applied to an uncalibrated cell.

Sudden shutdown at 20–30% on the XPA v1405 after a cell swap

When the original cell ages, its internal resistance climbs. The v1405's modem radio and screen backlight draw brief high-current spikes that cause the aged cell's terminal voltage to sag below the BMS cutoff threshold — even when the fuel gauge still reads 20–30%. Swapping in a fresh 1250mAh cell resolves the voltage sag, but the fuel gauge IC is still calibrated to the old cell's curve. The phone may still shut down at a false floor until the IC recalibrates. Run one full discharge below 5% and charge to 100% without interruption to reset the coulomb counter.

Battery percentage jumping erratically after installation

The XPA v1405 uses a fuel gauge IC that tracks charge state by integrating current over time against a stored cell model. A new cell has different impedance characteristics than the degraded cell it replaces, so the IC's stored model is immediately out of sync. This mismatch shows as percentage jumps — typically 10–15% swings in either direction during the first few cycles. Two full discharge-and-charge cycles at standard current will rebuild the IC's internal model. After the second full cycle, readings stabilise and track actual cell voltage within ±3%.