HP ENVY X2 11 CMOS Replacement Battery 3V 150mAh 1126.12

HP ENVY X2 11 — 3V Lithium CMOS Backup Battery (1126.12)

This is the CMOS/RTC coin cell for the HP ENVY X2 11 series, including the TPN-104 and ENVY X2 11-G010NR. It runs at 3V with a 150mAh (0.45Wh) capacity. The cell powers the real-time clock and BIOS SRAM when the laptop is off or disconnected from AC power.

• ENVY X2 11 and TPN-104 platform: These models share the same motherboard RTC circuit and coin cell socket, using OEM part numbers 1126.12 and 1110.12. The connector and cell dimensions (25.63 × 20.21 × 3.60 mm) match the factory specification exactly.
• Bench tested on actual hardware: We confirmed the cell holds above the 2.8V CMOS retention threshold under no-load conditions and that the BIOS correctly reads date and time after a full AC disconnect cycle with this cell installed.
• Post-install clock correction: After fitting the new cell, enter BIOS setup immediately and set the correct date and time, then save and exit. The RTC circuit resets to a default date during any power interruption — including the swap itself — and must be corrected manually before the system clock is accurate.

BIOS clock resetting to 2000 after every power cycle

When the CMOS cell drops below approximately 2.8V, it can no longer hold the RTC circuit or SRAM content during AC disconnect. The BIOS loses track of date and time and falls back to its hardcoded default — typically January 1, 2000. This happens even if the system boots normally while plugged in, because the failing cell only matters when mains power is absent. Replacing the coin cell and setting the correct date in BIOS once resolves it permanently.

CMOS checksum error appearing on boot screen

A checksum error means the BIOS compared its stored configuration to what it found in CMOS SRAM and the values did not match — a sign the cell was fully depleted and settings were lost entirely, not just the clock. The BIOS flags this before POST completes and may prompt to enter setup. Install the replacement cell, enter BIOS, restore your settings, set the correct date and time, then save and exit. The checksum error will not reappear once the SRAM is backed by a cell holding above 2.8V.