HTC P6500 Replacement Battery 3.7V 2200mAh 35H00077-00M

HTC P6500 / Sirius 100 — 3.7V Li-Polymer Replacement Battery (35H00077-00M)

This is a 3.7V, 2200mAh Li-Polymer replacement cell for the HTC P6500, P6550, Sirius 100, and Sedna. It slots directly into the original battery compartment and matches the OEM voltage rail. The OEM part numbers covered are 35H00077-00M, 35H00077-02M, and TRIN160.

• P6500, P6550, Sirius 100, and Sedna compatibility: These four models share the same battery bay dimensions, connector pinout, and 3.7V supply rail. The BMS handshake is consistent across the group, so one cell covers all four without modification.
• Bench tested on actual hardware: We ran this cell through full charge-discharge cycles on the P6500 platform. The BMS accepted the cell on first connection, charge termination triggered correctly at 4.2V, and low-voltage cutoff engaged at 3.0V under load without false trips.
• First-cycle fuel gauge reset: On first use, disable any fast-charge mode and run one complete discharge-to-charge cycle. This lets the phone's fuel gauge IC map the new cell's discharge curve before high-current charging pushes current into an uncalibrated state.

Why the P6500 reports wrong battery percentage after a cell swap

The P6500 uses a coulomb counter that was calibrated against the original cell's impedance and discharge curve. A new Li-Polymer cell has a different internal resistance profile, so the fuel gauge IC reads the state-of-charge incorrectly until it relearns. The fix is one full discharge to automatic power-off followed by a full uninterrupted charge to 100%. After that single cycle, the percentage readout stabilises and tracks accurately.

Sudden shutdown at 20–30% remaining on the replacement cell

This is a voltage cliff issue, not a capacity problem. Under peak modem or screen load, the cell voltage dips sharply below the phone's hardware cutoff threshold — around 3.2V — before the fuel gauge reports empty. The phone cuts power to protect the board, even though the displayed percentage still looks safe. Fully charge the battery, run the fuel gauge calibration cycle described above, and verify that charge termination reaches 4.2V — if it falls short, the charge IC is throttling early and needs a longer conditioning cycle.