About this replacement
Samsung NP-Q1 Series — 11.1V Li-ion Replacement Battery (AA-PB0UC3B)
This is an 11.1V, 2400mAh Li-ion replacement battery for the Samsung Q1 ultraportable. It fits the NP-Q1, NP-Q1-M000, NP-Q1SSD, and Q1-900 Casomii among other Q1 variants. The OEM part numbers AA-PB0UC3B, AA-PL0UC3B/E, AA-PL0UC6B, and AA-PL0UC6B/E all cross-reference to this cell.
- Q1 series compatibility: These models share the same 11.1V three-cell configuration, identical connector pinout, and BMS handshake protocol. Swapping between Q1 variants does not require firmware changes — the pack ID registers the same across the lineup.
- Bench tested on actual hardware: We cycled this cell through full charge and discharge on Q1 hardware. The BMS held the charge curve correctly, terminated at spec voltage, and did not trigger any overcurrent or thermal fault flags during the discharge load cycle.
- First-cycle calibration on the Q1: After installing, run a 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 a cell swap — skipping this step leaves the fuel gauge IC reading against the old cell's data.
BIOS reporting battery health as poor after replacement on the Q1
The Q1's BIOS stores learned cycle data from the previous cell in non-volatile memory. When a new cell is installed, the BIOS compares live readings against that stored profile and flags a health mismatch. This is an EEPROM data conflict — not a fault with the new battery. Running one complete discharge-to-hibernate then a full uninterrupted charge clears the conflict and allows the BIOS to build a fresh baseline against the new cell's actual capacity curve.
Q1 shutting down at 20–30% charge shown on the gauge
This happens when the fuel gauge IC has not yet calibrated against the new cell. The old cell's voltage-to-capacity curve is still mapped in the gauge controller, so it misreads the new cell's actual state of charge. Under full CPU and display load, the real cell voltage drops faster than the gauge predicts, hitting the BMS low-voltage cutoff before the displayed percentage reaches zero. Run two complete discharge and charge cycles — by the second full cycle the fuel gauge IC recalibrates and the shutdowns stop.