About this replacement
Archos 5.5 Hero V3 — 3.8V Li-Polymer Replacement Battery (AC55GR)
This is a 3.8V, 2800mAh lithium-polymer battery for the Archos 5.5 Hero V3 and BSF28 smartphones. It replaces OEM part number AC55GR. Capacity is rated at 10.64Wh from a 86.30 x 65.80 x 4.00mm cell.
- 5.5 Hero V3 and BSF28 compatibility: Both models share the same charge IC, connector pinout, and BMS handshake protocol — one cell covers both. Swapping to a different voltage spec will trip the charge controller and prevent a full charge cycle.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the 5.5 Hero V3. The BMS accepted the new cell without fault flags, and the charge IC reached termination current at the correct voltage ceiling.
- Fuel gauge recalibration on first use: On first installation, disable fast charging and run one full discharge-to-charge cycle at standard current. The fuel gauge IC on this phone is calibrated to the old cell's discharge curve — a slow first cycle gives the coulomb counter a clean reference point before any high-current charging starts.
Sudden shutdown at 20–30% on the Archos 5.5 Hero V3
This is a voltage cliff problem, not a capacity problem. When the modem transmits or the screen peaks in brightness, current draw spikes sharply. A degraded or freshly installed cell with an uncalibrated fuel gauge cannot sustain rail voltage under that load, and the protection circuit cuts output before the OS registers zero. After one complete discharge-charge cycle at standard current, the coulomb counter recalibrates its low-end curve and the early shutdowns typically stop. If shutdowns persist past two full cycles, check that the cell connector is fully seated — a partial connection raises contact resistance and accelerates voltage sag under load.
OS showing wrong battery percentage after cell replacement
The fuel gauge IC stores a learned discharge curve from the original cell — it does not reset automatically when you fit a new battery. Until the IC runs at least one full cycle against the new cell, percentage readings will drift, jump, or plateau at numbers that do not match actual charge state. Charge the phone to 100% using the standard charger, then drain it fully until automatic shutdown, then charge again to 100% without interruption. After that cycle the coulomb counter has a real reference and reported percentages will track accurately.