About this replacement
Samsung NP530U4B Series — 7.4V Li-Polymer Replacement Battery (AA-PBYN8AB)
This 7.4V, 6100mAh lithium-polymer battery replaces the AA-PBYN8AB cell in Samsung's NP530U4B ultrabook line. It fits the NP530U4B, NP530U4B-A01US, 535U4C-S01, and BA43-00339A among others. Capacity is 45.14Wh — matched to the original cell spec.
- NP530U4B and 535U4C shared platform: These models run the same thin-chassis board layout and share an identical connector pinout, BMS handshake protocol, and 7.4V nominal rail. One replacement cell covers the full group without adapter changes.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the NP530U4B platform. The BMS communicated correctly over SMBus, charge termination triggered at the right cutoff, and the protection circuit responded normally to load transitions across the CPU and display together.
- Post-install calibration on the NP530U4B: After fitting this cell, run one full discharge down 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
Samsung's BIOS reads health data stored in the old cell's EEPROM during every boot. When a new cell arrives, that EEPROM contains no matching cycle history, so the BIOS flags the battery as degraded or unknown. This is a firmware read issue, not a fault with the replacement cell. Run two complete discharge-to-hibernate and uninterrupted charge-to-100% cycles — the learn cycle rewrites the reference data and the warning clears.
Laptop shutting down at 20–30% shown on the gauge
This happens when the fuel gauge IC still holds calibration data from the degraded original cell. The percentage shown no longer maps accurately to the new cell's actual voltage curve. Under combined CPU and display load, the cell voltage drops faster than the gauge predicts, and the BMS triggers a hard cutoff before the reported percentage reaches zero. Run a full discharge to hibernate and a full uninterrupted charge twice — the fuel gauge IC recalibrates against the new cell and the shutdowns stop. Check system battery info after the second cycle; voltage at shutdown should now be at or below 6.4V rather than cutting early.