HP Chromebook 14B HSTNN-IB9S Replacement Battery 11.55V 4750mAh

HP Chromebook 14B / X360 14C Series — 11.55V Li-Polymer Replacement Battery (HSTNN-IB9S)

This is a 11.55V, 4750mAh (54.86Wh) Li-Polymer replacement battery for the HP Chromebook 14B and Chromebook X360 14C series. It fits the X360 14C-CC0013DX and X360 14C-CD0000CA alongside the standard 14B chassis. OEM part numbers include HSTNN-IB9S, HSTNN-OB1V, SI03XL, SI03058XL, M12329-1D1, and M12329-AC1.

• 14B and X360 14C platform fit: Both the 14B and X360 14C lines run the same voltage rail and use the same three-cell SI03 connector pinout with a shared BMS handshake. That common architecture is why one cell covers both chassis variants without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a 14C unit. The BMS accepted the cell, reported state-of-charge correctly after two calibration cycles, and did not trigger a low-voltage cutoff prematurely under combined CPU and display load.
• Post-install calibration on ChromeOS: After fitting, let the battery discharge fully until the Chromebook hibernates, then charge uninterrupted to 100% without interruption. ChromeOS uses that full cycle to recalibrate the fuel gauge IC against the new cell — skipping it leaves the charge percentage reading unreliable for weeks.

Why ChromeOS reports poor battery health immediately after a cell swap

The EC firmware on the 14B and X360 14C stores learned battery data — full charge capacity, cycle count, wear level — in EEPROM on the old cell. When a new cell is installed, that EEPROM data is gone, and ChromeOS reads the blank state as degraded or unknown health. This is not a fault with the replacement cell. Running one complete discharge-to-hibernate followed by a full uninterrupted charge resets the learn cycle and clears the warning. After two to three full cycles the health indicator should stabilise at normal.

Chromebook shuts down abruptly while the battery gauge still shows 20–25%

This happens when the fuel gauge IC has not yet mapped the new cell's actual voltage curve. Under combined CPU, display backlight, and Wi-Fi load, the cell voltage drops faster than the uncalibrated gauge expects — the BMS sees the voltage floor and cuts power before the displayed percentage reaches zero. It looks like sudden shutdown but the root cause is a mismatched discharge curve in the gauge's model. The fix is the same calibration cycle: discharge to hibernate cutoff, then charge straight to 100%. After that full reference cycle the gauge adjusts its model to the new cell and the early shutdowns stop.