OnePlus ACE 150W Replacement Battery BLP921 7.74V 2150mAh

OnePlus ACE 150W — 7.74V Li-Polymer Replacement Battery (BLP921)

This is a Li-Polymer replacement battery for the OnePlus ACE 150W smartphone. It carries OEM part number BLP921 and runs at 7.74V with 2150mAh (16.64Wh) capacity. Fits the ACE 150W when the original cell has degraded past usable charge retention.

• ACE 150W platform fit: The BLP921 matches the voltage rail, connector pinout, and BMS handshake required by the ACE 150W charge IC. Substituting a cell with a different nominal voltage or authentication profile will cause the charge circuit to reject it outright.
• Bench tested on actual hardware: We ran the BLP921 through charge and discharge cycles on the ACE 150W platform. The BMS accepted the cell without fault flags, and the charge IC progressed normally through CC and CV phases.
• Fuel gauge recalibration after install: On first use, disable fast charging and run one full discharge-charge cycle at standard current. This lets the fuel gauge IC map the new cell's discharge curve before 150W fast charging pushes high current into an uncalibrated cell — otherwise the percentage readout will drift.

Sudden shutdown at 20–30% on the ACE 150W after a cell swap

The ACE 150W's modem and display together draw enough current to expose a voltage cliff in a new cell before the fuel gauge IC has learned its actual discharge curve. When the cell voltage drops below the BMS cutoff threshold under that combined load, the phone shuts down even though the reported percentage still shows charge remaining. The fuel gauge IC is still referencing the old cell's coulomb curve. One full discharge-to-shutdown, then a complete charge at standard rate, recalibrates the counter against the new cell and moves the reported percentage back in line with actual cell voltage.

150W fast charge not initiating on the first cycle after replacement

OnePlus' proprietary fast charge protocol requires a handshake between the charger, the phone's charge IC, and the BMS. On a freshly installed cell, the BMS may report an unrecognised state to the charge IC, which causes it to fall back to standard 5W input as a precaution. This is not a fault with the cell or the charger. Complete one full charge-discharge cycle at standard current first — on the second cycle, the BMS state registers correctly and fast charging re-engages at full rate.