About this replacement
Samsung NP900X3A Series 9 — 7.4V Li-Polymer Replacement Battery (AA-PLAN6AR)
This 7.4V, 5200mAh Li-Polymer battery replaces the AA-PLAN6AR (also BA43-00292A) in the Samsung Series 9 NP900X3A ultrabook. It fits the NP900X3A, 900X3A-A01, 900X3A-01IT, 900X3A-A05US, and additional variants in the same lineup. Capacity is 38.48Wh — matching the OEM specification for this slim 2011–2012 platform.
- NP900X3A platform fit: All NP900X3A variants share the same 7.4V two-cell Li-Polymer pack, the same flat ribbon connector, and the same BMS handshake with the BIOS fuel gauge IC. Swapping within this family does not require a firmware change.
- Bench tested on actual hardware: We cycled this cell on an NP900X3A unit and confirmed the BMS communicated charge state correctly from the first cycle. The pack reached full cell voltage without triggering a premature cutoff or BIOS health error under standard load.
- Post-install calibration on the Series 9: After fitting this battery, run the laptop down to hibernate-cutoff under normal use, then charge uninterrupted to 100%. This forces the BIOS fuel gauge IC to re-learn the new cell's capacity curve and clears the inaccurate health warning that typically appears after any cell swap on this platform.
BIOS reporting battery health as poor immediately after replacement
The Series 9 BIOS stores charge history data from the previous cell in EEPROM. When a new pack is detected, the fuel gauge IC compares the new cell against that stored history and flags a mismatch as poor health. The cell itself is not faulty — the EEPROM data is stale. One full discharge-to-hibernate followed by an uninterrupted charge to 100% resets the learn cycle and clears the warning. If the flag persists after two full cycles, check the BIOS battery settings page for a manual reset option.
Laptop shuts down abruptly at 20–30% shown on the gauge
This happens when the fuel gauge IC has not yet calibrated against the new cell's actual discharge curve. The OS reads a percentage derived from the old cell's profile, so the displayed figure and real cell voltage diverge. Under combined CPU and display load, the actual cell voltage drops below the BMS cutoff threshold before the gauge reaches 0% — triggering a hard shutdown. Run two full discharge-to-hibernate and full-charge cycles to let the IC re-map the curve. After calibration, the gauge should align with real voltage to within a few percent at the 3.5V-per-cell floor.