Amazon S12-T5 Tablet Replacement Battery 3.8V 3400mAh

Amazon Fire Tablet — 3.8V Li-Polymer Replacement Battery (S12-T5)

This 3.8V, 3400mAh (12.92Wh) lithium-polymer cell replaces the original S12-T5 battery in Amazon Fire tablets. It fits units using OEM part numbers S12-T5, S12-T5-A, 58-000067, and 58-000067(1ICP4/59/139). Install it when the original cell no longer holds a charge or fails to power the device.

• Multi-part-number compatibility: Amazon produced this battery under several OEM codes across production runs — S12-T5, S12-T5-A, and two 58-000067 variants. They share the same 141.90 × 57.90 × 3.00 mm footprint, the same 3.8V nominal rail, and the same connector pinout. This cell fits all of them.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a Fire tablet test unit, confirmed the BMS accepted the new cell without fault flags, and verified the protection circuit responded correctly to both over-voltage and under-voltage cutoff thresholds.
• Post-swap fuel gauge reset: After installation, run the tablet down to automatic shutoff, then charge uninterrupted to 100% without using the device. This gives the fuel gauge IC a full reference cycle against the new cell and corrects the inaccurate percentage readings that appear after any battery swap.

Fire tablet shutting down at 15–25% after battery replacement

This is a voltage cliff problem, not a defective cell. Under combined display-on and Wi-Fi load, the tablet's power rail draws enough current to pull the cell voltage below the BMS cutoff threshold before the percentage gauge reaches zero. The fuel gauge IC is still calibrated to the old cell's discharge curve, so it reports a higher percentage than the actual remaining energy. One full discharge-to-shutoff cycle followed by an uninterrupted charge to 100% resets the calibration and eliminates the premature shutdown.

Fast charging unavailable after battery swap

Some Fire tablets use a charge negotiation handshake between the charge IC and the battery's protection circuit. On a freshly installed cell, this handshake may not complete on the first plug-in, so the charger defaults to standard 5V/1A input instead of the higher-rate profile. Plug in the original Amazon charger — third-party adapters may not carry the correct negotiation signal. If fast charge still does not activate after the first full cycle completes, unplug and reconnect; the charge IC re-runs negotiation at each new connection event.