About this replacement
Dell XPS 15z / L511Z Series — 14.8V Li-Polymer Replacement Battery (075WY2)
This 14.8V 4400mAh (65.12Wh) Li-Polymer cell replaces the original battery in the Dell XPS 15z and L511Z series ultrabooks. It covers OEM part numbers 075WY2, 0HTR7, 0NMV5C, 75WY2, NMV5C, and OHTR7. If your XPS 15z no longer holds a charge or fails to power on from battery, this is the direct replacement.
- XPS 15z and L511Z compatibility: The XPS 15z (L511X) and L511Z share the same battery bay dimensions, connector pinout, and BMS communication protocol — all variants on this platform accept the same 14.8V four-cell Li-Polymer pack without modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the XPS 15z platform. The BMS handshake completed without error, charge termination triggered correctly at full voltage, and no thermal events occurred during high-load draw.
- Post-install calibration on the XPS 15z: After fitting this cell, 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 the XPS firmware throws after every cell swap.
Why the XPS 15z BIOS reports poor battery health after a cell swap
The XPS 15z reads battery health from EEPROM data stored on the original cell. When a new cell goes in, that EEPROM data is blank or mismatched — the BIOS has no cycle history to reference and flags the battery as degraded. This is a firmware artefact, not a fault with the replacement cell. Running the full learn cycle described above gives the BIOS the data it needs to update its health estimate correctly.
XPS 15z shutting down at 20–30% battery shown on screen
If the laptop cuts out while the OS still shows 20–30% remaining, the fuel gauge IC has not yet calibrated against the new cell's actual voltage curve. The old cell's curve is still cached, so the reported percentage drifts significantly from real charge state. Under combined CPU and display load, the actual cell voltage drops below the cutoff threshold before the gauge catches up. Two to three full discharge-to-hibernate and uninterrupted-charge cycles will force the IC to re-map the curve against the new cell — after that, shutdown should align with the display hitting 5% or the hibernate threshold set in Windows power settings.