About this replacement
Samsung Galaxy Book FLEX 930QCJ / 950XCJ — 15.4V Li-Polymer Replacement Battery (AA-PBRN4ZU)
This is a 15.4V, 4300mAh (66.22Wh) lithium-polymer battery for Samsung Galaxy Book FLEX laptops. It fits the 930QCJ, 930XCJ, 950XCJ, Galaxy Book FLEX NP950QCG-K01HK, and over 38 additional Samsung notebook variants sharing the AA-PBRN4ZU specification. If your original cell no longer holds charge or the laptop reports battery health as poor, this is the direct swap.
- Galaxy Book FLEX platform fit: These models share a common 15.4V power rail, the same BMS handshake protocol, and an identical physical connector pinout — which is why one cell covers the full 930/950 series. The BMS communicates state-of-charge data back to the BIOS over the SMBus line; the replacement cell carries that same communication stack.
- Bench tested on actual hardware: We ran charge and discharge cycles on this cell against a 930XCJ board. The BMS held voltage within spec across the full range and the protection circuit triggered correctly at low-cell threshold, stopping discharge before damage occurred.
- First-cycle reset after installation: After fitting this cell, run the laptop down to hibernate cutoff — do not interrupt — then charge uninterrupted to 100%. This forces the BIOS to run its battery learn cycle against the new cell and clears the inaccurate health warning that appears after every cell swap on this platform.
Why the Galaxy Book FLEX BIOS reports poor health immediately after a cell swap
The Samsung BIOS reads health data from EEPROM registers stored in the original cell's fuel gauge IC. When a new cell goes in, those registers contain factory defaults, not real-world cycle data — so the BIOS flags the battery as degraded or unknown before any learning has occurred. This is a firmware read issue, not a fault with the replacement cell. Running one full discharge-to-hibernate then an uninterrupted charge to 100% lets the BIOS rewrite those registers against the actual new cell chemistry. After one or two complete cycles the health status normalises.
Laptop shuts down at 20–30% shown on the new cell
This happens when the fuel gauge IC has not yet calibrated against the new cell's voltage curve. The OS reads a fuel gauge estimate, not a live cell voltage — so it shows 25% while the cell is already below the safe discharge floor under full CPU and display load. The laptop cuts power to protect the cell before the displayed percentage reaches zero. Fix this by completing two full discharge-to-hibernate cycles followed by full uninterrupted charges. After calibration, the gauge tracks the actual voltage curve and shutdowns stop occurring above 5%.