About this replacement
Samsung Galaxy Tab A 8.4 2020 — 3.85V Li-Polymer Replacement Battery (EB-BT307ABY)
This 3.85V, 4800mAh Li-Polymer battery replaces the OEM EB-BT307ABY cell in the Samsung Galaxy Tab A 8.4 2020 (SM-T307U). It fits tablets where the original cell no longer holds charge across a full day of browsing, video, or productivity use. Capacity figure is 4800mAh — use this value, not anything listed elsewhere.
- SM-T307U fit: The SM-T307U is the US-market variant of the Tab A 8.4 2020. It uses the EB-BT307ABY form factor — 103.26 x 99.70 x 3.00mm — with a specific flex connector orientation that differs from adjacent Tab A generations. This cell matches that connector and fits the chassis without modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the SM-T307U platform and confirmed the BMS handshake completed on first charge. The fuel gauge IC accepted the new cell and began tracking state-of-charge without fault codes.
- Post-swap fuel gauge reset: After installation, run the tablet down to automatic shutoff, then charge uninterrupted to 100% without using the device. The SM-T307U fuel gauge IC calibrates against the new cell during this cycle and clears the inaccurate percentage readings that typically appear in the first few hours after a swap.
Tab A 8.4 2020 shutting down at 15–25% remaining
The SM-T307U draws significant combined load when the display is at full brightness and Wi-Fi is actively transferring data. Under that load, a degraded or freshly swapped cell can drop below the BMS cutoff voltage before the reported percentage reaches zero. The tablet powers off abruptly because the voltage collapses faster than the fuel gauge updates. After completing one full discharge-and-charge calibration cycle, the reported percentage aligns with the actual cell voltage curve and the early shutdowns stop.
Fast charging unavailable after battery replacement on SM-T307U
The Tab A 8.4 2020 uses Samsung's Adaptive Fast Charging protocol, which requires the charge IC to negotiate with both the charger and the battery's BMS before enabling the higher charge rate. On a freshly installed cell, this negotiation sometimes fails on the first cycle because the BMS hasn't completed its initial handshake. Connect the original Samsung charger — not a third-party USB-C adapter — and complete one full uninterrupted charge to 100%. The protocol re-negotiates on the second cycle and fast charging becomes available from 0V cell recovery upward.