About this replacement
Samsung Galaxy Tab S 10.5 — 3.8V Li-Polymer Replacement Battery (EB-BT800FBC)
This is a 3.8V, 7900mAh Li-Polymer replacement battery for the Samsung Galaxy Tab S 10.5. It fits the SM-T800 WiFi and SM-T805C 4G variants, along with eleven additional confirmed model numbers. Swap it in when the original cell no longer holds charge or the tablet shuts down unexpectedly before reaching zero percent.
- SM-T800 and SM-T805 series coverage: Both the WiFi-only and 4G LTE variants share the same battery bay geometry, connector pinout, and BMS handshake protocol — so one cell fits both board revisions without modification.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on an SM-T800 board. The BMS accepted the cell immediately, reported state-of-charge correctly after one calibration cycle, and held voltage within spec under combined display and WiFi load.
- Fuel gauge recalibration after swap: After fitting this battery, run the tablet down to automatic shutoff — do not force-power-off — then charge uninterrupted to 100%. This single cycle lets the fuel gauge IC map its thresholds to the new cell and eliminates the percentage-jumping behaviour that appears in the first few hours of use.
Galaxy Tab S 10.5 shutting down at 15–25% remaining after battery replacement
This happens because the fuel gauge IC still holds the voltage-to-capacity curve it learned from the degraded original cell. When the new cell's actual voltage at 20% doesn't match that stored curve, the IC interprets it as a critical low and triggers a shutdown. The fix is a single full discharge-to-cutoff followed by an uninterrupted charge to 100%. After that cycle, the IC relearns the new cell's discharge profile and the early shutdowns stop.
Fast charging not available after fitting the EB-BT800FBC
The Tab S 10.5 uses Samsung's Adaptive Fast Charging protocol, which requires the charge controller to complete a successful handshake with a recognised cell before enabling the higher current path. On a fresh battery, this handshake sometimes only completes after one full standard charge cycle at the default 5V rate. If the fast charge indicator doesn't appear on the first charge, let it complete at standard rate, disconnect, then reconnect with the original Samsung charger. The handshake succeeds at that point and fast charge activates — confirmed at 9V negotiation on the bench.