HP Pavilion X2 10-J014TU Replacement Battery 3.8V 8250mAh

HP Pavilion X2 10-J014TU — 3.8V Li-Polymer Replacement Battery (810749-421)

This 3.8V, 8250mAh Li-Polymer cell replaces the internal battery in the HP Pavilion X2 10 detachable tablet screen. It fits the tablet portion of the hybrid — not the keyboard dock. Compatible part numbers include DO02XL, HSTNN-LB6Y, and TPN-I121 among others listed in the product data.

• Pavilion X2 10 tablet screen compatibility: The X2 10 series uses a single flat Li-Polymer cell seated inside the detachable display unit. All models in this family — J013TU, J014TU, K2N77PA — share the same connector pinout, voltage rail, and BMS handshake, so one cell covers the full range.
• Bench tested on actual hardware: We cycled this cell through charge, full load discharge, and BMS cutoff on a Pavilion X2 10 unit. The BMS accepted the cell without fault flags, and the protection circuit tripped cleanly at low-voltage cutoff as expected.
• Post-install calibration on the X2 10: After fitting this cell, run the tablet down to hibernate cutoff under normal use, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that routinely appears after any cell swap in this series.

Why the X2 10 tablet reports poor battery health immediately after a cell swap

The Pavilion X2 10 stores charge history in EEPROM tied to the original cell. When a new cell is installed, the BIOS reads that stale data and flags health as degraded — even though the replacement is fresh. This is a firmware behaviour, not a fault with the new cell. Running one full discharge-to-hibernate then a complete uninterrupted charge gives the BIOS enough data to overwrite the old EEPROM values. After one to two full cycles, the health status normalises.

Fuel gauge reading wildly wrong for the first few charges

The X2 10 uses a fuel gauge IC that tracks capacity by counting coulombs against a stored cell profile. A new cell resets that baseline, so the gauge reads inaccurately — jumping from 60% to 15% or showing full charge well before the cell is actually topped up. This is not a defective battery. The IC needs two to three full discharge and charge cycles to re-map against the new cell's actual chemistry. After the third full cycle, percentage readings stabilise and the gauge tracks within a few percent of real charge state.