Samsung NP-X280 Notebook Replacement Battery 7.4V 3800mAh

Samsung NP-X280 / NT-X280 Series — 7.4V Li-ion Replacement Battery (AA-PB3VC4B)

This is a 7.4V, 3800mAh (28.12Wh) Li-ion battery for the Samsung NP-X280, NT-X280, NT-X181, and NT-X180 notebook series. It slots into the same bay as the original AA-PB3VC4B and AA-PB3VC4E cells. Install it when the original pack no longer holds a charge or the laptop only runs on wall power.

• NP-X280 and NT-X series compatibility: These models share the same 7.4V two-cell rail, identical connector pinout, and the same BMS handshake protocol — which is why one pack covers all four variants. The BMS reads cell voltage on pins 3 and 4; a mismatch here causes the laptop to reject the pack entirely.
• Bench tested on actual hardware: We ran this cell on the NP-X280 platform and logged the BMS charge cycle from 0V recovery through CC/CV cutoff. The protection circuit held charge termination at 8.4V and did not trigger overcurrent cutoff during a full CPU stress load cycle.
• First-cycle calibration on the X280: 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.

Why the NP-X280 BIOS reports poor battery health after a cell swap

The X280 BIOS reads health data stored in the old pack's EEPROM and compares it against the new cell's voltage signature. A fresh cell has a different charge curve than a degraded original, so the BIOS flags it as faulted on first boot. This is not a defect in the replacement cell. Run one full discharge-to-hibernate cycle followed by an uninterrupted charge to 100%, and the BIOS recalibrates its learn cycle against the new chemistry. After two to three full cycles, the health indicator corrects itself.

Laptop shutting down at 20–30% charge shown on screen

This happens when the fuel gauge IC is still calibrated to the old cell's discharge curve. The gauge reads 25% remaining, but the actual cell voltage has already dropped below the load threshold the CPU and display draw together — the laptop hits a voltage cliff and shuts off without warning. The fix is a full calibration cycle: let the laptop drain completely to hibernate-cutoff under normal use load, then charge to 100% without interruption. After two full cycles the gauge IC re-maps to the new cell and shutdown at false percentages stops. Target full charge endpoint is 8.4V across the pack.