HTC Desire C Replacement Battery BA S850 3.7V 2200mAh

HTC Desire C / A320E — 3.7V Li-ion Replacement Battery (BA S850)

This is a 3.7V, 2200mAh Li-ion replacement battery for the HTC Desire C and A320E smartphones. It fits the original battery slot directly, using OEM part references BA S850, 35H00194-00M, 99H10905-00, and BL01100. If your Desire C no longer holds charge through a normal day, this cell restores the capacity the original had when new.

• Desire C and A320E compatibility: Both the Desire C and A320E share the same battery bay geometry, voltage rail, and connector pinout — one cell fits both variants without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the Desire C platform. The BMS handshake completed correctly, charge termination triggered at 4.2V, and the protection circuit responded to over-discharge conditions as expected.
• Fuel gauge recalibration on first use: After fitting this cell, run one full discharge to automatic shutdown followed by an uninterrupted charge to 100% before using the phone normally. The Desire C's fuel gauge IC calibrates its coulomb counter against the actual cell discharge curve on that first full cycle — skipping it causes the percentage readout to drift.

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

The Desire C uses a fuel gauge IC that was calibrated to the original cell's internal resistance profile. A new cell with different impedance characteristics can cause the gauge to misread the remaining charge, triggering an abrupt shutdown before the display reaches 0%. The phone cuts power because the voltage drops below the BMS protection threshold under load — even though the gauge still shows charge remaining. Running one complete discharge-charge cycle after installation lets the IC update its internal model to match the new cell, which eliminates most premature shutdowns.

Phone won't power on after the replacement battery sat in storage

Li-ion cells self-discharge in storage, and if this battery was stored for an extended period before installation, the cell voltage may have dropped below 2.5V per cell — the threshold at which the BMS enters lockout to prevent damage. Plugging in the charger may show no response at all. Leave the phone connected to a wall charger, not a computer USB port, for 20–30 minutes without pressing the power button. Once the cell recovers above the BMS re-enable threshold, the phone will begin a normal charge cycle and power on.