About this replacement
HP ProBook x360 435 G7 — 11.55V Li-Polymer Replacement Battery (SX03XL)
This is an 11.55V, 3550mAh (41Wh) lithium-polymer replacement battery for the HP ProBook x360 435 G7 convertible laptop. It replaces OEM part numbers SX03XL, HSTNN-DB9P, HSTNN-IB9D, L78125-005, and related variants. If your ProBook x360 no longer holds a charge or won't run unplugged, this cell restores portable operation.
- ProBook x360 435 G7 fitment: All variants in the 435 G7 line share the same 11.55V three-cell configuration, connector pinout, and BMS handshake protocol. The SX03XL form factor also matches the physical bay dimensions — 263.60 × 79.10 × 5.80mm — so no modification is needed during installation.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the ProBook x360 435 G7 platform. The BMS communicated correctly with the EC, charge current stepped down at the expected cutoff threshold, and the cell accepted a full charge without triggering protection flags.
- Post-swap calibration on the x360 435 G7: After installing, run one full discharge to hibernate-cutoff, then charge uninterrupted to 100%. 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 replacement
The ProBook x360 435 G7 stores battery health metrics in EEPROM on the original cell. When a new cell goes in, the BIOS reads stale data from that cycle history and flags the replacement as degraded — even though the cell is new. This is not a fault with the replacement battery. Run one full discharge-to-hibernate then a complete uninterrupted charge to 100%. After two to three cycles, the BIOS learn cycle rewrites the health register and the warning clears.
ProBook x360 shutting down at 20–30% battery shown
This happens when the fuel gauge IC is still calibrated to the old cell's discharge curve. Under combined CPU and display load, the new cell hits a voltage point the IC misreads as near-empty, triggering an early shutdown. The fix is calibration: discharge fully to automatic hibernate, then charge to 100% without interruption. Repeat this two to three times. After calibration, the gauge tracks the new cell's actual voltage curve and the early shutdowns stop.