About this replacement
Samsung Galaxy A90 5G — 3.85V Li-Polymer Replacement Battery (EB-BA908ABY)
This 3.85V, 4400mAh Li-Polymer cell replaces the original battery in the Samsung Galaxy A90 5G. It fits the SM-A908, SM-A908B, and SM-A908F variants and restores capacity when the original cell has degraded past usable thresholds. Part number EB-BA908ABY confirms direct compatibility with the A90 5G battery bay and connector.
- SM-A908 variant coverage: The SM-A908, SM-A908B, and SM-A908F share the same battery bay dimensions, connector pinout, and BMS handshake protocol — one cell covers all three. The 78.40 × 64.65 × 4.66mm form factor matches the original housing with no modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the SM-A908 platform. The BMS accepted the charge IC handshake without error flags, and coulomb counter registration completed normally across the first full cycle.
- Fuel gauge recalibration on first use: Disable fast charging for the first complete discharge-charge cycle after installation. The fuel gauge IC is calibrated to the old cell's discharge curve — one full slow cycle at standard charge current lets it remap against the new cell before high-current charging is applied.
Why the A90 5G reports wrong battery percentage after a cell swap
The Galaxy A90 5G uses a coulomb counter inside the fuel gauge IC to estimate state of charge. That counter was calibrated against the original cell's internal resistance and discharge slope. When a new cell goes in, the stored curve no longer matches actual cell behaviour, so the percentage display reads high or low. One full discharge to auto-shutdown followed by a complete charge to 100% at standard current resets the calibration baseline.
Sudden shutdown at 20–30% on the replacement cell
The A90 5G's 5G modem and display draw burst current that can spike well above the steady-state load. If the fuel gauge IC has not yet recalibrated, it may show 25% while actual cell voltage has already dropped to the BMS cutoff threshold — around 3.0V under load. The BMS reads voltage directly and cuts power to protect the cell, regardless of what the OS percentage shows. Run two full discharge-charge cycles and the fuel gauge will track actual cell voltage closely enough to eliminate the premature cutoff.