Motorola XT2245 NP40 Replacement Battery 3.91V 3900mAh

Motorola Edge 30 Neo / XT2245 — 3.91V Li-Polymer Replacement Battery (NP40)

This is a 3900mAh (15.25Wh) Li-Polymer replacement battery for the Motorola XT2245 and Edge 30 Neo smartphones. It fits directly where the original NP40 cell sits, matching the same 80.90 × 61.30 × 4.30mm footprint and connector. Voltage is 3.91V nominal — same as factory spec.

• XT2245 and Edge 30 Neo compatibility: Both model designations share the same physical chassis, battery bay dimensions, and BMS communication protocol. The NP40 part number covers both — one SKU, one connector, same voltage rail. No adapter or modification needed.
• Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on an XT2245 unit. The BMS accepted the cell without fault codes, charge current ramped normally through CC/CV stages, and the protection circuit triggered correctly at low-voltage cutoff.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging begins. Skip this step and the percentage readout will drift — the IC is still calibrated to the old, degraded cell.

Sudden shutdown at 20–30% on the replacement NP40 cell

This is a voltage cliff issue, not a capacity defect. When the modem transmits or the display brightness spikes, current draw rises sharply. If the fuel gauge IC hasn't finished recalibrating to the new cell's discharge curve, it can report 25% remaining while actual terminal voltage has already dropped below the protection threshold. The BMS trips and the phone shuts off. One full discharge-charge cycle with fast charging disabled lets the coulomb counter resync to the new cell. After that cycle, shutdowns at high percentage readings typically stop.

USB-PD fast charge not accepted on the first cycle after replacement

The Edge 30 Neo's charge IC performs a handshake with the BMS before enabling high-current charging. On a new cell, internal impedance is higher than the depleted original — the charge IC can read this as an anomaly and hold the charge rate at trickle (around 5W) for the first partial cycle. This is normal behaviour, not a fault. Let the phone charge slowly to 100% on the first cycle, then disconnect and allow one full discharge before plugging back in. Fast charging should engage normally from the second cycle onward.