About this replacement
Gigaset ME / GS55-6 Series — 3.85V Li-Polymer Replacement Battery (GI01)
This is a 3.85V, 2500mAh (9.63Wh) Li-Polymer cell that replaces the original GI01 battery in the Gigaset ME, Gigaset ME FCB, and GS55-6 / GS55-6me smartphones. It fits when the original cell has degraded, swells, or no longer holds a charge through a normal day of use. Same voltage, same connector, same physical footprint at 68.70 × 60.00 × 3.90mm.
- ME and GS55-6 series compatibility: These models share the same 3.85V power rail, identical connector pinout, and the same BMS handshake protocol — so one cell covers all four listed variants without modification or adapter.
- Bench tested on actual hardware: We cycled this cell on the GS55-6 platform and confirmed the BMS accepted the new cell without triggering charge faults. The protection circuit engaged correctly at both low-voltage cutoff and full-charge termination.
- Fuel gauge recalibration after swap: After fitting this cell, disable fast charging and run one complete discharge down to automatic shutdown, then charge to 100% without interruption. The phone's coulomb counter needs this full cycle to map the new cell's discharge curve accurately before percentage readings stabilise.
Sudden shutdown at 20–25% on the Gigaset ME after a cell swap
A new Li-Polymer cell has a slightly different internal resistance profile than the aged cell the fuel gauge IC was calibrated against. When the modem fires a high-current burst — during a call, a GPS fix, or a screen-on wake — voltage sags below the hardware cutoff threshold even though the reported percentage looks safe. The phone shuts down not because the cell is empty, but because the voltage rail momentarily collapses under load. One full discharge-to-shutdown cycle followed by an uninterrupted charge to 100% lets the coulomb counter re-anchor its low-voltage floor to the new cell, and the premature cutoffs stop.
Phone feels warm near the battery during the first few charges
A fresh Li-Polymer cell typically has higher internal impedance than one that has been cycled. The charge IC pushes current into that higher impedance, and the extra resistance converts some charge energy to heat. This is most pronounced in the first two to three charge cycles and reduces as the cell's impedance settles. If the device surface temperature stays below roughly 40°C and drops off after those early cycles, the behaviour is normal. If it persists beyond cycle three or the phone becomes too hot to hold, check that no debris is trapped between the cell and the rear cover, and confirm the charger output does not exceed 5V/2A.