Samsung Galaxy F55 5G Replacement Battery 3.88V 4850mAh

Samsung Galaxy F55 5G / M55 5G — 3.88V Li-Polymer Replacement Battery (GH81-25792A)

This 3.88V, 4850mAh (18.82Wh) Li-Polymer cell replaces the original battery in the Samsung Galaxy F55 5G, Galaxy M55 5G, Galaxy Y55 5G, and SM-C5560. It targets phones where the original cell has degraded to the point of failing normal daily use. Voltage, connector pinout, and physical dimensions (88.20 × 63.60 × 4.70mm) match the OEM specification.

• F55 / M55 / Y55 5G platform compatibility: These models share the same battery bay geometry, flex connector, and BMS handshake protocol. The fuel gauge IC on each reads cell voltage against the same lookup table, so swapping this cell across any of those boards works without firmware conflict.
• Bench tested on actual hardware: We cycled this cell on the SM-C5560 board and confirmed the BMS accepted the cell without a fault flag. Charge current ramped correctly through CC/CV stages, and the protection circuit tripped at the expected over-voltage threshold on a deliberate overcharge test.
• First-cycle fast charge protocol: On first use after installation, disable fast charging for one full discharge-charge cycle. This lets the fuel gauge IC recalibrate its coulomb counter against the new cell's discharge curve before high-current charging pushes into an uncalibrated state.

Sudden shutdown at 20–30% on the Galaxy F55 5G after a cell swap

This happens because the fuel gauge IC is still using the impedance model it built around the old, degraded cell. When the modem fires a burst transmission or the screen hits peak brightness, current draw spikes and the new cell's actual terminal voltage drops below the shutdown threshold — even though the reported percentage looks safe. The gauge reads capacity from a stored curve, not live voltage, so the mismatch causes an abrupt cutoff. One full discharge down to 3.3V followed by a slow charge to 100% forces the IC to rebuild its model against the new cell.

USB-PD fast charge not activating on the first cycle after replacement

On the first charge after installation, some Galaxy F55 5G units default to standard 5V/1A input instead of negotiating the higher voltage PD contract. The charge IC holds back fast charge until it has logged at least one recognised full cycle from the new cell's BMS. Plug into a USB-PD charger, let the phone charge fully at standard rate without interrupting it, then disconnect and power the phone on normally. On the second charge session, the fast charge indicator should appear within the first few minutes of plugging in.