About this replacement
HTC Smart / Rome Series — 3.7V Li-ion Replacement Battery (TOPA160)
This 3.7V, 2200mAh Li-ion battery replaces the original cell in the HTC Smart, Rome, Rome 100, and F3188. OEM part numbers are TOPA160 and 35H00125-11M. Fit this when the existing battery no longer holds a charge or the phone has stopped powering on entirely.
- Smart and Rome platform fit: The Smart, Rome, and Rome 100 share the same battery bay dimensions and connector pinout. All run on a 3.7V single-cell Li-ion rail with identical BMS handshake logic, so one cell covers the full group without modification.
- Bench tested on actual hardware: We ran this cell through a full charge cycle on the HTC Smart. The BMS accepted the cell without fault flags, charge termination triggered correctly at 4.2V, and protection cutoff engaged as expected at the low-voltage threshold.
- Fuel gauge recalibration on first use: After fitting this cell, disable any fast-charge adapter and run one complete discharge down to auto-shutdown, then charge to 100% on a standard 5V/1A supply. This lets the fuel gauge IC map its coulomb counter against the new cell's discharge curve before high-current charging begins.
Why the HTC Smart shuts down suddenly at 20–30% after a cell swap
A new cell has a steeper voltage-drop curve than the degraded cell the fuel gauge IC was originally calibrated to. When the modem fires a high-current burst — during a call or data sync — voltage sags faster than the IC predicts. The phone interprets this sag as a critically low cell and triggers an emergency shutdown, even though the reported percentage shows charge remaining. One full discharge-to-shutdown cycle followed by a complete charge teaches the IC where the real voltage cliff sits on the new cell.
Phone warm near the battery compartment during the first charge
A fresh cell typically arrives with higher internal impedance than a conditioned one. In the first charge cycle the charge IC pushes current into this higher resistance, which generates more heat than normal until the cell's impedance settles. This is expected behaviour during the first one or two cycles and should reduce noticeably after that. If the compartment stays hot beyond the second full charge, check that the charger output is no higher than 5V/1A — higher voltages stress the charge IC on this platform.