Asus C21N1334 Transformer Book T200TA Replacement Battery 7.6V 4900mAh

Asus Transformer Book T200TA Series — 7.6V Li-Polymer Replacement Battery (C21N1334)

This is a 7.6V 4900mAh (37.24Wh) Li-Polymer battery for the Asus Transformer Book T200TA tablet portion of the 2-in-1 hybrid. It replaces OEM part numbers C21N1334, 0B200-00870000, 0B200-00870200, and 0B200-00870300. It fits the T200TA, T200TA 12", T200TA-1R, T200TA-DB12T-CA, and related T200TA variants.

• T200TA tablet unit compatibility: The T200TA line separates its battery cells between the tablet portion and the keyboard dock. This cell powers only the tablet half. All listed T200TA variants share the same 7.6V two-cell configuration, same connector pinout, and the same BMS handshake with the Atom Z3775 platform's charge IC.
• Bench tested on actual hardware: We ran this cell through charge acceptance, BMS communication, and cut-off verification on the T200TA platform. The protection circuit responded correctly to over-charge and over-discharge thresholds, and the charge IC recognised the cell without error flags.
• Fuel gauge recalibration after install: After fitting this battery, run the tablet down to automatic shutoff, then charge it uninterrupted to 100% without disconnecting. The T200TA's fuel gauge IC is calibrated to the old cell's curve. One full discharge-to-shutoff cycle resets that calibration against the new cell and clears inaccurate percentage readings.

T200TA shutting down at 15–25% battery remaining

This happens because the fuel gauge IC mapped the discharge voltage curve of the old, degraded cell. When the new cell hits what the gauge still treats as a low-voltage cliff, it triggers an OS shutdown before the cell is actually depleted. The fix is a single full recalibration cycle — discharge to automatic shutoff, then charge to 100% uninterrupted. After that cycle, the gauge tracks the new cell's actual curve and shutdowns at low percentages stop.

Fast charging not resuming after a battery swap

The T200TA charge IC uses a handshake with the battery's protection circuit before it allows higher charge current. On a fresh cell, this handshake runs during the first complete charge cycle. Until that cycle completes, the IC defaults to a lower safe current. Plug the device into its original Asus adapter and let it charge fully without interruption — after one accepted cycle, normal charge rates resume and the behaviour does not repeat.