B-N2 Vivo X50 Compatible Battery 3.87V 4100mAh Li-Polymer

Vivo X50 / X50 5G — 3.87V Li-Polymer Replacement Battery (B-N2)

This is a 3.87V, 4100mAh (15.87Wh) lithium-polymer cell built to replace the original B-N2 battery in the Vivo X50 and X50 5G (model numbers V2001A, V2001). If your X50 shuts down unexpectedly, charges slowly, or holds far less charge than it once did, the cell has degraded and needs replacing. Swapping the battery restores the phone to its original power capacity without replacing the handset.

• X50 / X50 5G platform fit: The V2001A and V2001 share the same battery bay dimensions (79.42 × 62.44 × 5.14mm), the same 3.87V nominal voltage rail, and the same BMS connector pinout — so one B-N2 cell covers both variants without modification.
• Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on the X50 platform, confirming BMS handshake, charge IC acceptance, and stable voltage delivery across screen-on and modem-active loads.
• Fuel gauge recalibration on first cycle: After installation, disable fast charging and run one complete discharge down to automatic shutdown, then charge to 100% on standard speed. This lets the X50's fuel gauge IC map its coulomb counter to the new cell's discharge curve before high-current charging begins.

Sudden shutdown at 20–30% on the Vivo X50 after a cell swap

This is a voltage cliff problem, not a capacity problem. When the X50's modem transmits or the AMOLED display peaks in brightness, current draw spikes hard. A new cell that hasn't been calibrated yet may drop below the BMS cutoff voltage under that load — even while the OS still reports 25% remaining. The fuel gauge IC is still reading from its old cell model, so the percentage shown doesn't match the actual cell voltage. One full discharge-charge cycle at standard speed recalibrates the coulomb counter and clears this behaviour.

USB fast charging not activating on the first cycle after replacement

On the first charge after a battery swap, the X50's charge IC runs a trickle-charge verification pass before it hands off to the fast-charge protocol. If the replacement cell arrives with low state-of-charge from storage, the IC can hold the phone in trickle mode for 10–20 minutes before fast charging kicks in — this is normal BMS behaviour, not a fault. Leaving the phone on a charger undisturbed through that initial phase allows the IC to confirm cell voltage is above the fast-charge entry threshold (typically 3.0V per cell). If fast charging still doesn't activate after a full first cycle, check that the charger output matches the Vivo FlashCharge spec — an underpowered adapter will hold the phone in standard charge mode indefinitely.