About this replacement
Dell Alienware X16 R1 — 11.55V Li-Polymer Replacement Battery (HP26N / M02R0)
This is an 11.55V, 7750mAh (89.51Wh) Li-Polymer battery for the Dell Alienware X16 and Alienware X16 R1 gaming laptop. It replaces OEM part numbers HP26N and M02R0. Install it when the original cell no longer holds a usable charge or the system forces constant AC operation.
- Alienware X16 and X16 R1 fit: Both the X16 and X16 R1 use the same physical cell format, connector pinout, and BMS handshake protocol — the HP26N part number covers both revisions without modification.
- Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on an X16 chassis. The BMS negotiated correctly with the Dell EC, charge current stepped down cleanly at the 80% threshold, and no false over-temperature flags were triggered.
- Post-install BIOS learn cycle: After fitting this battery, run the system down to hibernate cutoff under normal use, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on Alienware hardware.
Why the Alienware X16 shuts down at 20–30% after a battery swap
The X16's fuel gauge IC calibrates its voltage-to-capacity curve against the old cell's EEPROM data. A new cell with a different internal resistance profile will hit a steeper voltage cliff under GPU-plus-display load than the gauge expects. When voltage drops below the EC's cutoff threshold, the system shuts off even though the displayed percentage is still 20–30%. Two to three full discharge-recharge cycles recalibrate the fuel gauge IC against the actual cell. After calibration, the shutdown behaviour stops.
BIOS reporting wrong Wh rating after cell replacement
Dell's BIOS reads the Wh value from the battery's EEPROM rather than measuring it directly. If the replacement cell's EEPROM stores a different rated Wh figure than the original — even by a small margin — BIOS will display that stored value, not the actual chemistry output. This is an EEPROM data difference, not a fault with the cell. The true delivered energy is 89.51Wh as rated on this SKU. To verify, check the cycle count and full charge capacity readout in Dell SupportAssist, which reflects measured values rather than the EEPROM-stored figure.