Vivo X80 Replacement Battery B-U5 7.78V 2200mAh

Vivo X80 / V2183A / V2144 — 7.78V Li-Polymer Replacement Battery (B-U5)

This is a 7.78V, 2200mAh Li-Polymer replacement battery for the Vivo X80 smartphone and its regional variants, V2183A and V2144. It replaces the original B-U5 cell when the factory battery has degraded, lost hold-charge capacity, or failed outright. Voltage and connector match the stock configuration — no modifications needed during installation.

• X80, V2183A, V2144 compatibility: All three model numbers share the same battery bay geometry, connector pinout, and BMS handshake protocol. The B-U5 part number covers this entire variant group — same 7.78V dual-cell arrangement and NTC thermistor line.
• Bench tested on actual hardware: We ran this cell through charge termination checks and BMS communication verification. The protection circuit responded correctly to overvoltage cutoff and temperature thresholds matched expected NTC readings throughout the cycle.
• Fuel gauge recalibration on first cycle: After installation, disable fast charging and run one full discharge down to auto-shutdown, then charge to 100% on standard 5W. This gives the coulomb counter a clean reference curve against the new cell before the charge IC starts pushing high-current bursts into an uncalibrated cell.

Sudden shutdown at 20–30% on the Vivo X80 after a cell swap

This happens because the fuel gauge IC is still running a lookup table calibrated to the old, degraded cell. A new cell holds higher voltage across its mid-range, then drops steeply near depletion — the fuel gauge misreads that cliff as 20–30% remaining. Under modem load or display brightness spikes, the actual cell voltage dips below the system cutoff threshold before the percentage hits zero. One full discharge-charge cycle on standard charging rewrites the reference points the coulomb counter uses to map voltage to percentage.

USB-PD or proprietary fast charge not activating after replacement

On the first charge cycle after a cell swap, the charge IC may stay in trickle or standard mode rather than negotiating the fast-charge protocol. The BMS on a new cell starts with conservative current limits until it logs a completed cycle and confirms thermal behaviour is within spec. This is normal — it is not a fault with the replacement battery or the charger. Charge once fully at standard rate, then reconnect the fast charger; the protocol handshake should activate from the second cycle onward.