About this replacement
Huawei P40 — 3.85V Li-Polymer Replacement Battery (HB525777ECW)
This is a 3800mAh Li-Polymer cell at 3.85V, replacing OEM part HB525777ECW and HB525777EEW in the Huawei P40 (ANA-AN00, ANA-TN00). It fits the stock battery bay with no modification. Capacity matches the factory spec at 14.63Wh.
- P40 ANA-AN00 and ANA-TN00 coverage: Both ANA variants run the same 3.85V power rail and use identical connector pinouts and BMS handshake logic, so a single cell serves both regional builds without any wiring or firmware difference.
- Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on the P40 platform. The BMS accepted the cell, fast charge signalling initialised correctly after one full cycle, and the fuel gauge IC tracked state of charge without erratic jumps.
- Fuel gauge recalibration on first use: After fitting this cell, disable fast charging for the first complete discharge-charge cycle. This lets the fuel gauge IC build an accurate discharge curve against the new cell before high-current charging pushes current into an uncalibrated state.
Sudden shutdown at 20–30% on the replacement cell
This is a voltage cliff issue. Under modem or display load, the new cell briefly drops below the BMS cutoff threshold even though the fuel gauge still reads 20–30%. The gauge was calibrated to the old, degraded cell curve and does not yet know the new cell's actual discharge profile. One full discharge to shutdown followed by an uninterrupted charge to 100% resets the coulomb counter. After that cycle, the reported percentage should track actual cell voltage accurately again.
Huawei SuperCharge not activating after cell replacement
On the first cycle after a cell swap, the charge IC on the P40 may not handshake with the new cell's BMS and will fall back to standard 5V charging. This is normal — the controller is reading cell impedance and temperature before allowing high-current negotiation. Charge the phone to 100% on a standard charger first, then power cycle the device. On the next charge session, SuperCharge should negotiate correctly and the charging indicator will show the higher wattage rate.