About this replacement
Samsung Galaxy Tab S8 Ultra — 3.88V Li-Polymer Replacement Battery (EB-BX906ABY)
This is a 3.88V, 10500mAh Li-Polymer replacement battery for the Samsung Galaxy Tab S8 Ultra tablet. It fits the SM-X900, SM-X906, and SM-X906B model variants. Swap it in when the original cell no longer holds charge or the tablet shuts down unexpectedly under load.
- SM-X900 and SM-X906 series compatibility: Both the Wi-Fi (SM-X900) and 5G (SM-X906/SM-X906B) variants use the same battery bay dimensions, connector pinout, and BMS handshake protocol — the EB-BX906ABY fits all without modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on a Galaxy Tab S8 Ultra unit. The BMS negotiated correctly with the charge IC, hit full cutoff at 4.35V, and reported state of charge without fault flags in the system diagnostic.
- Fuel gauge recalibration after install: After fitting this battery, run one full discharge to automatic shutoff, then charge uninterrupted to 100%. This resets the fuel gauge IC calibration against the new cell and eliminates the inaccurate percentage readings that appear immediately after a swap.
Galaxy Tab S8 Ultra shutting down at 15–25% remaining
The Tab S8 Ultra drives a 14.6-inch AMOLED display alongside Wi-Fi, 5G, and the Snapdragon 8 Gen 1 — a combined load that pulls hard on the cell under peak use. An aged battery hits a voltage cliff earlier than expected under this load, and the BMS triggers a protective shutdown before the percentage gauge reaches zero. The fuel gauge IC was calibrated to the old cell's discharge curve, so the reported percentage no longer reflects the actual cell voltage. After fitting the replacement, run one full discharge-to-shutoff cycle followed by an uninterrupted charge to 100% to remap the gauge to the new cell.
Fast charging not resuming after battery replacement
The Tab S8 Ultra uses Samsung's 45W USB-PD fast charge protocol, which requires a completed charge handshake between the charge IC and the new cell before it unlocks higher wattage. On a fresh replacement, the first charge cycle may run at standard speed while the charge IC profiles the new cell. Plug in using the original 45W adapter and cable — third-party cables frequently lack the wiring to carry the full PD negotiation. After one complete charge cycle to 100%, fast charging resumes at full wattage on subsequent sessions.