HTC Desire 825 Replacement Battery B2PUK100 3.8V 3000mAh

HTC Desire 825 — 3.8V Li-Polymer Replacement Battery (B2PUK100)

This 3.8V, 3000mAh Li-Polymer battery replaces the original cell in the HTC Desire 825, Desire 825 TD-LTE, D825u, and Desire 825 Dual SIM. It carries OEM part numbers B2PUK100, 35H00258-03M, and 35H00258-00M. Swap it in when the original cell can no longer hold charge through a normal day of calls, browsing, and standby.

• Desire 825 platform fit: All variants in this family — TD-LTE, Dual SIM, D825u — share the same 3.8V battery bay, connector pinout, and BMS handshake logic, so one cell covers the full range without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the Desire 825 platform and confirmed the BMS accepted the cell, reported state-of-charge correctly, and did not trigger overcurrent or overvoltage cutoff at any point during the test sequence.
• Fuel gauge recalibration on first use: On the first use after installation, disable fast charging and run one complete discharge-to-charge cycle. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before high-current charging begins.

Why the Desire 825 reports wrong battery percentage after a cell swap

The Desire 825 uses a fuel gauge IC that builds its capacity model from the discharge curve of the original cell. When a new cell goes in, the IC is still referencing the old curve. This mismatch causes the percentage readout to jump or sit high while the real voltage is already falling. One full discharge cycle — run the phone down to automatic shutdown, then charge uninterrupted to 100% — forces the IC to remap against the new cell. After that single cycle, percentage readings stabilise.

Sudden shutdown at 20–30% on the replacement cell

This happens when the cell voltage drops below the modem or display's minimum supply threshold under load, even though the fuel gauge still shows charge remaining. On the Desire 825, simultaneous LTE, screen-on, and GPS load can pull enough current to cause a sharp voltage sag that triggers the BMS low-voltage cutoff. The fix is the same full recalibration cycle — once the fuel gauge IC has an accurate curve, it begins warning and throttling load before voltage collapses. If shutdowns continue past two full cycles, check that resting cell voltage sits above 3.7V after a full charge.