About this replacement
HP Pro X2 612 G1 Keyboard — 7.4V Li-Polymer Replacement Battery (KT02XL)
The KT02XL is a 7.4V, 3150mAh Li-Polymer battery for the detachable keyboard unit of the HP Pro X2 612 G1 hybrid tablet-laptop. It fits the wireless keyboard accessory — not the tablet itself. Part numbers 753330-1B1, 753330-421, HSTNN-I19X, HSTNN-IB6F, and HSTNN-LB6F all cross to this same cell.
- Pro X2 612 G1 Keyboard unit fit: The keyboard accessory runs its own independent power rail at 7.4V, separate from the tablet's main battery. This cell matches that rail voltage and the internal BMS handshake the keyboard firmware expects — so the host system recognises it correctly on attach.
- Bench tested on actual hardware: We ran the KT02XL through charge and discharge cycles on a Pro X2 612 G1 keyboard dock. The BMS reported state-of-charge accurately to the host tablet within two cycles, and charge termination triggered cleanly at rated capacity without overrun.
- Post-install calibration on the keyboard unit: After fitting, let the keyboard discharge fully until it stops responding, then charge it uninterrupted to 100% before use. The keyboard's fuel gauge IC calibrates against the new cell during that first complete cycle — skipping it leaves the reported charge level inaccurate for weeks.
Why the Pro X2 612 G1 keyboard shows "0% battery" immediately after a cell swap
The keyboard's fuel gauge IC stores learned capacity data in its EEPROM tied to the old cell. When a new cell goes in, that stored data no longer matches actual cell behaviour, so the gauge reads zero or reports an error state to the tablet. This is not a wiring or compatibility fault. Running one full discharge-to-cutoff followed by a complete uninterrupted charge forces the IC to rewrite its EEPROM with data from the new cell. After that cycle, the tablet should display an accurate charge percentage.
Keyboard battery stuck below 80% charge after replacement
HP's firmware on the Pro X2 612 G1 includes a BIOS-controlled charge limit that can cap the keyboard battery at 80% to reduce cell stress over time. This setting persists across cell swaps — it is a firmware state, not a battery fault. Access HP BIOS Setup (F10 at boot), locate the Battery Care Function or similar power management option, and disable or adjust the charge threshold. Once cleared, the cell will charge to the full 7.4V terminal voltage.