About this replacement
Samsung NT501R5L Series — 11.4V Li-Polymer Replacement Battery (AA-PBUN3AB)
This 11.4V, 3700mAh (42.18Wh) Li-Polymer battery replaces the AA-PBUN3AB cell in Samsung NT501R5L-series notebooks. It fits the NT501R5L-M15/C, NT501R5L-L05/R, NT501R5L-M1S/C, NT501R5L-M1G/C, and over 290 additional NT501R5L variants. The connector, BMS handshake protocol, and physical dimensions match the original exactly.
- NT501R5L platform fit: All NT501R5L variants share the same 11.4V three-cell Li-Polymer configuration, identical connector pinout, and the same BMS communication line the Samsung EC firmware expects. One cell part number covers the full platform.
- Bench tested on actual hardware: We cycled this cell through charge and load on an NT501R5L unit. The BMS authenticated without error, the EC accepted the pack, and charge current tapered correctly at full state of charge. No false fault codes appeared.
- Post-swap calibration cycle: After installing, discharge the laptop through normal use until it hibernates at the low-battery cutoff — do not force shutdown. Then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap.
BIOS reporting battery health as poor after swapping the AA-PBUN3AB
Samsung's EC reads cycle count and health data from the old cell's EEPROM. When a new cell arrives, that EEPROM data resets, and the firmware flags the pack as degraded because the stored figures don't match what it expects from a used unit. This is a firmware state issue, not a defect in the replacement cell. One full discharge-to-hibernate followed by an uninterrupted charge to 100% lets the BIOS battery learn cycle rewrite its reference data against the new cell. After one or two cycles, the health indicator returns to normal.
Laptop shuts down at 20–30% shown on the fuel gauge
This happens when the fuel gauge IC hasn't been calibrated against the new cell's actual discharge curve. The IC is still referencing voltage-to-capacity mappings from the old, degraded cell, so it reads the remaining charge as higher than it actually is — right up until the cell voltage drops below the BMS cutoff threshold. The laptop then cuts power with charge still displayed on screen. Run two full discharge-to-hibernate cycles, charging to 100% each time, to let the fuel gauge IC relearn the curve. After calibration, the gauge should align with actual cell voltage and not drop below 3.2V per cell at shutdown.