About this replacement
Samsung Q318 Series — 11.1V Li-ion Replacement Battery (AA-PB9NC6B)
This is an 11.1V 4400mAh Li-ion battery for the Samsung Q318 notebook series, including the Q318-DSOE, Q318-DS0H, and Q318-DS02. It replaces the original AA-PB9NC6B and a broad range of cross-compatible OEM part numbers including AA-PB9NS6B, AA-PL9NC6W, and AA-PB9MC6B. Physical dimensions are 204.00 × 48.20 × 20.00mm — confirm these against your existing cell before installing.
- Q318 series connector and BMS compatibility: All Q318 variants listed share the same 11.1V three-cell Li-ion architecture, connector pinout, and BMS handshake protocol. The replacement cell communicates on the same SMBus line as the original, so the laptop recognises the pack at POST without any firmware workaround.
- Bench tested on actual hardware: We cycled this cell through full charge and discharge on a Q318 unit. The BMS held charge termination correctly at 12.6V and engaged protection cutoff at the low-voltage threshold without triggering false over-current trips under combined CPU and display load.
- First-cycle calibration on the Q318: After installation, run the battery down until the laptop hibernates on its own, then charge uninterrupted to 100% without using the machine. This resets the BIOS battery learn cycle and clears the inaccurate health or unknown-status warning that appears after every cell swap on this platform.
Why the Q318 BIOS reports poor health or "unknown" immediately after a battery swap
The Q318 stores learned charge data in EEPROM on the battery pack itself. When you fit a new cell, the BIOS reads that EEPROM as blank or mismatched against its last known state, then flags the battery as degraded or unrecognised. This is not a fault with the replacement cell — it is the system's fuel gauge IC losing its reference point. Running one complete discharge-to-hibernate followed by an uninterrupted charge to 100% gives the BIOS enough data to rebuild its capacity baseline. After two to three full cycles, the health report normalises and the warning clears.
Q318 shutting down suddenly with 20–30% charge still showing on screen
This happens when aged cells cannot sustain the voltage rail under combined CPU and display load — the cell voltage drops below the BMS cutoff threshold faster than the fuel gauge can track it, so the displayed percentage is still high when the system dies. The fuel gauge IC on the Q318 calibrates its percentage estimate against actual cell voltage over time, so a new cell showing this behaviour on the first few cycles is normal — it has not yet learned the new cell's discharge curve. Force the calibration by letting the laptop run on battery under normal workload until it hibernates, then charge fully. After two cycles the gauge catches up to the new cell's voltage profile and the premature shutdowns stop.