About this replacement
HP ProBook x360 440 G1 — 11.4V Li-Polymer Replacement Battery (HSTNN-UB7P)
This 11.4V, 4150mAh (47.31Wh) Li-Polymer battery replaces the original HSTNN-UB7P cell in the HP ProBook x360 440 G1 and related x360 convertible models. It fits the full-rotation hinge platform, including the x360 11 G3 Education Edition and x360 11 G4. Cross-reference OEM part numbers L12717-421, L12717-541, L12791-855, and RU03XL before installing.
- ProBook x360 platform fit: The 440 G1 and x360 11 Education series share the same 11.4V three-cell Li-Polymer rail, connector pinout, and BMS handshake protocol — that is why one SKU covers all these models without modification.
- Bench tested on actual hardware: We ran this cell through charge, discharge, and BMS communication cycles on the x360 440 G1 chassis. The protection circuit responded correctly to over-charge and over-discharge thresholds, and the BIOS recognised the cell without error on first boot.
- Post-install calibration on the x360: After fitting this battery, run one full discharge to hibernate cutoff, then charge uninterrupted to 100% without using the machine. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on this platform.
BIOS reporting poor battery health immediately after fitting a new cell
The HP ProBook x360 BIOS stores discharge curve data from the previous cell in its battery learn table. When a new cell is fitted, that stored data no longer matches the actual cell behaviour, so the BIOS flags the battery as degraded. This is not a fault with the replacement — it is a mismatch between old EEPROM data and a fresh chemistry profile. Running one complete discharge-to-hibernate followed by a full uninterrupted charge gives the BIOS enough data to rebuild an accurate learn table. After two or three cycles, the health warning clears and the reported capacity stabilises.
Laptop shuts down at 20–30% charge shown on screen
When the CPU and display both draw maximum load simultaneously on the x360 440 G1, the battery must sustain voltage above the BMS cutoff threshold continuously. If the fuel gauge IC is still calibrating against the new cell, the percentage shown on screen can lag well behind the real state of charge — so the machine cuts out at what looks like 25% but is actually near-empty. This is a calibration gap, not a failing cell. Run the discharge-recharge cycle described above to synchronise the fuel gauge IC with the new cell's actual voltage curve. After calibration, shutdowns should not occur until the display reads below 5%.