About this replacement
Asus VivoTab TF810CD — 7.4V Li-Polymer Replacement Battery (C21-TF810CD)
This 7.4V, 3300mAh Li-Polymer battery replaces the C21-TF810CD cell in the Asus VivoTab TF810CD Windows tablet. It fits the tablet unit directly and restores the portable computing functionality lost when the original cell degrades. Capacity is 3300mAh (24.42Wh), matching the stock specification.
- VivoTab TF810CD fit: The TF810CD uses a thin Li-Polymer pack at 211.70 x 94.50 x 3.30mm. This replacement matches that footprint and the same 7.4V nominal rail the board expects. The connector and BMS handshake align with the tablet's charge controller so Windows reads cell state without modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the TF810CD platform. The BMS responded correctly to charge termination signals, and the fuel gauge IC registered the new cell without throwing low-battery errors at full capacity.
- Post-swap fuel gauge reset: After installing this battery, run one full discharge to automatic shutoff, then charge uninterrupted to 100%. This forces the fuel gauge IC to recalibrate against the new cell and clears the inaccurate percentage readings that commonly appear immediately after a swap.
Why the TF810CD shuts down at 15–25% remaining
The TF810CD draws peak current when the display backlight is at full brightness and Wi-Fi is active simultaneously. A degraded or uncalibrated cell hits its low-voltage cutoff under that combined load well before the fuel gauge reaches 0%. The BMS trips the cutoff to protect the cell, so Windows never reaches a graceful shutdown. After installing a fresh cell, run the full recalibration cycle above — one complete discharge to shutoff, then a full uninterrupted charge — and the premature cutoffs stop.
Tablet showing 100% charge but dropping fast in the first 20 minutes of use
This is fuel gauge drift — the IC is still calibrated to the old cell's discharge curve, so it reads the new cell's voltage incorrectly at the top of the range. The percentage collapses quickly until the curve aligns with what the IC expects. This is not a fault with the replacement cell. One full discharge-to-shutoff followed by an uninterrupted charge to 100% resets the calibration, and the percentage will track accurately from that point forward.