Vivo A97 5G Replacement Battery BLP923 3.87V 4850mAh

Vivo A97 5G / PFTM10 — 3.87V Li-Polymer Replacement Battery (BLP923)

The BLP923 is a 4850mAh lithium-polymer cell rated at 3.87V nominal, built as a direct cell replacement for the Vivo A97 5G (model PFTM10). It fits the original battery bay without modification. Capacity is 18.77Wh — matching the OEM specification.

• A97 5G / PFTM10 fit: Both model designations reference the same hardware platform. The battery connector, BMS handshake pinout, and physical dimensions (94.20 × 65.00 × 4.30mm) are identical across both variants, so one cell covers the full range.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the A97 5G platform. The BMS accepted the cell without fault codes, and the charge IC completed a full CC/CV cycle to 4.35V with no thermal interruption.
• Fuel gauge recalibration on first use: After installation, disable fast charging and run one complete discharge-to-charge cycle at standard rate. This lets the fuel gauge IC map the new cell's discharge curve before the coulomb counter locks in its reference points. Skipping this step causes percentage drift in the first week.

Sudden shutdown at 20–30% on the A97 5G after a cell swap

This happens when the fuel gauge IC is still calibrated to the old cell's internal resistance curve. The new cell's voltage drops faster under 5G modem and display load than the IC expects. The phone interprets this as a critically low voltage event and triggers an emergency shutdown — even though the cell still has charge. One full discharge below 5% followed by an uninterrupted charge to 100% resets the coulomb counter and resolves this.

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

On the first cycle after a cell swap, the A97 5G's charge IC sometimes withholds fast charge negotiation until it has verified the new BMS is responding within expected voltage and temperature thresholds. This is a protection behaviour, not a fault. Charge the phone once at standard speed using the original cable and adapter. Fast charge protocol re-enables automatically on the second cycle once the charge IC has logged a clean baseline from the new cell.