HTC Desire Z BA S450 Replacement Battery 3.7V 1500mAh

HTC Desire Z / A7272 — 3.7V Li-ion Replacement Battery (BA S450)

This is a 3.7V, 1500mAh Li-ion cell built to fit the HTC Desire Z (A7272), Vision, and BB96100, plus seven additional compatible models. It replaces OEM part numbers BA S450, 35H00140-00M, and 35H00140-01M. If your Desire Z is shutting down early or no longer holding a charge through a normal day, this cell restores the original voltage rail the phone expects.

• Desire Z / A7272 platform compatibility: The Desire Z, Vision, and BB96100 share the same PCB footprint, connector pinout, and BMS handshake protocol, which is why a single cell covers all of them. The phone's charge IC expects a 3.7V nominal cell — swapping to anything outside that window triggers a protection cutoff.
• Bench tested on actual hardware: We ran this cell through full charge and load cycles on a Desire Z unit. The BMS accepted the handshake without faults, and the charge IC topped the cell to 4.2V within normal parameters — no thermal event, no cutoff error in the status register.
• Fuel gauge recalibration after installation: On first use, disable sync and background data, then run one complete discharge down to auto-shutdown followed by a full uninterrupted charge. The Desire Z's fuel gauge IC is calibrated to the old cell's impedance curve — one full cycle resets the coulomb counter against the new cell before the OS can misread state-of-charge.

Sudden shutdown at 20–30% on the Desire Z after a cell swap

This happens because the fuel gauge IC is still using the discharge curve it learned from the old, degraded cell. When the new cell hits a voltage region the IC hasn't mapped, it loses track of remaining capacity and triggers an emergency shutdown — even though the cell has charge left. The modem radio and screen create a combined current spike the uncalibrated gauge interprets as a cliff. Run one full discharge-to-shutdown cycle without interrupting the charge afterward, and the coulomb counter rebuilds an accurate curve for the new cell.

Phone reports wrong battery percentage after installing the replacement cell

The Desire Z's fuel gauge IC stores learned capacity data from the previous cell in non-volatile memory — it doesn't auto-reset when you swap hardware. That stored curve no longer matches the new cell's actual voltage-to-capacity relationship, so percentage readings drift, jump, or stall at fixed values. Power the phone completely off, reinsert the battery, and run a single uninterrupted discharge-to-shutdown followed by a charge to 100% with the screen off. After that cycle, the IC recalibrates its internal register against the new cell and percentage reporting stabilises.