Dell XPS 1318 CMOS Backup Battery 3V 200mAh 23.22056.001

Dell XPS 1318 / M1330 / M1340 — 3V Lithium CMOS Backup Battery (23.22056.001)

This is a 3V, 200mAh lithium coin cell that backs the CMOS circuit on Dell XPS and Inspiron motherboards. It holds BIOS settings, hardware configuration, and the real-time clock when main power is removed. Fits the XPS 1318, XPS M1330, XPS M1340, Inspiron 1520, and eight additional models listed in the compatibility table.

• XPS and Inspiron CMOS circuit: These Dell boards use a dedicated SRAM-backed RTC circuit that draws continuously from this cell — even with the laptop unplugged and the main battery removed. All listed models share the same connector footprint, cell format (20 × 20 × 3.8mm), and 3V retention requirement.
• Bench tested on actual hardware: We confirmed the cell holds above 2.8V under the low-current SRAM load the Dell RTC circuit applies. The board accepted the cell without BMS handshake — this is a passive cell with no onboard logic.
• Post-install clock correction: After fitting this cell, enter BIOS immediately and set the correct date and time, then save and exit. The RTC circuit resets to a default value after any power interruption — the new cell cannot restore what was previously stored, only retain what you write next.

BIOS clock resetting to 2000 after every power cycle

The Dell RTC circuit requires the CMOS cell to stay above 2.8V to hold the clock register. When the cell drops below that threshold, the board defaults the clock to January 1, 2000 on every cold boot — even if the laptop runs normally on main power. The cell itself may read 2.9–3.0V on a multimeter at rest but sag below retention voltage under the continuous microamp draw of the SRAM circuit. Replacing the cell and resetting the date in BIOS stops the loop.

CMOS checksum error on boot after fitting a new coin cell

A checksum error immediately after installing a fresh cell usually means the board read a corrupted or blank CMOS state during the swap — not a fault with the new cell. The error appears because the SRAM lost power long enough to zero out, and the board flags the mismatch between stored and expected values. Clear it by entering BIOS setup, confirming or resetting all values to default, then saving and exiting. If the error returns on the next cold boot, check that the cell connector spring is making clean contact — oxidised or bent springs produce intermittent voltage drops that retrigger the checksum failure.