XP-13 MWG Atom V Replacement Battery 3.7V 1350mAh

MWG Atom V — 3.7V Li-ion Replacement Battery (XP-13)

This is a 3.7V, 1350mAh Li-ion cell built to replace the OEM XP-13 battery in the MWG Atom V smartphone. It restores power to the device after the original cell has degraded, lost capacity, or stopped holding a charge. Voltage and capacity match the original spec exactly.

• MWG Atom V fit: The Atom V uses a 3.7V single-cell Li-ion architecture with a direct connector match to the XP-13 footprint. The replacement cell shares the same 64.44 × 38.58 × 5.72mm dimensions, so it seats flush in the battery bay without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a controlled rig. The BMS accepted a standard 1C charge rate, voltage peaked at 4.2V at full charge, and the protection circuit tripped correctly at the low-voltage cutoff threshold — no anomalous behaviour at either end.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one full discharge-charge cycle at standard rate. This lets the fuel gauge IC map the new cell's actual discharge curve before any high-current session pushes charge into an uncalibrated cell.

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

This happens because the fuel gauge IC still holds the discharge curve from the old, degraded cell. When the new cell hits a voltage point the IC associates with a lower state of charge, it calls a shutdown early. The phone cuts out even though usable capacity remains in the cell. One full discharge-charge cycle at standard rate forces the coulomb counter to re-anchor against the new cell's actual voltage cliff — typically around 3.5V under modem load on the Atom V.

MWG Atom V shows erratic percentage jumps after replacement

Erratic percentage readings — jumping from 45% to 61% or dropping 10% in seconds — point to a fuel gauge IC that has not yet characterised the new cell. The IC uses stored data from the previous cell's impedance profile, and a fresh cell with different internal resistance throws those estimates off. This is not a fault in the replacement cell. Run two complete discharge-charge cycles without fast charging and the gauge will stabilise as it builds an accurate impedance model for the new cell.