BV-4BWA Microsoft Lumia 1320 Replacement Battery 3.8V 3500mAh

Microsoft Lumia 1320 — 3.8V Li-Polymer Replacement Battery (BV-4BWA)

This is a 3.8V, 3500mAh lithium-polymer replacement battery for the Microsoft Lumia 1320 smartphone. It uses OEM part number BV-4BWA and slots directly into the Lumia 1320's battery bay. At 13.3Wh, it matches the original cell's energy spec exactly.

• Lumia 1320 fit: The Lumia 1320 uses a fixed battery bay sized for BV-4BWA at 93.75 × 68.36 × 3.79mm. The connector orientation and tab spacing match the original cell, so the Windows Phone firmware negotiates with the BMS without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a Lumia 1320 unit. The BMS accepted the charge IC handshake on the first cycle, and the phone's fuel gauge IC began tracking cell voltage without throwing a battery fault.
• Fuel gauge recalibration after swap: After installing this cell, run one complete discharge down to auto-shutdown, then charge uninterrupted to 100% before resuming normal use. This lets the Lumia 1320's coulomb counter anchor its calibration to the new cell's actual discharge curve.

Why the Lumia 1320 reports wrong battery percentage after a cell swap

The Lumia 1320 uses a fuel gauge IC that builds its percentage model from accumulated charge and discharge data on the original cell. When you install a new cell, the IC still references its old calibration curve. The percentage it reports can be off by 15–25% until the IC collects fresh data. One full discharge-to-shutdown followed by a complete charge cycle forces the coulomb counter to reset its reference points against the new cell.

Sudden shutdown at 20–30% on the replacement cell

This happens when the phone's modem or display pulls a current spike the cell cannot sustain at that state of charge, causing voltage to sag below the BMS cutoff threshold. The phone shuts down even though the fuel gauge still shows charge remaining — the percentage is wrong, not the battery. Run one full calibration cycle first. If shutdowns continue after calibration, check that the cell seated fully and the connector tab has solid contact — a partial connection raises internal resistance and worsens voltage sag under load.