Acer Aspire 5570 CMOS Battery 3V 18mAh 0420.07

Acer Aspire 5570 — 3V Lithium CMOS Replacement Battery (0420.07)

This is the CMOS backup cell for the Acer Aspire 5570 motherboard. It runs at 3V with an 18mAh capacity, matching OEM part number 0420.07. The cell keeps the RTC circuit, BIOS settings, and system clock alive when mains power is removed.

• Aspire 5570 motherboard fit: The 5570 uses a dedicated coin cell holder wired directly to the RTC and CMOS SRAM circuit. This cell matches the OEM footprint at 16.00 × 12.80 × 2.80mm and the two-pin connector orientation used on that board revision.
• Bench tested on actual hardware: We measured open-circuit voltage at 3.0V and confirmed stable retention voltage above the 2.8V minimum threshold that the Aspire 5570 BIOS requires to hold settings across a full power cycle.
• Post-install clock correction: After fitting the new cell, enter BIOS immediately and set the correct date and time, then save and exit. The RTC circuit loses its reference during the swap, so the clock defaults to a factory value — correcting it in BIOS writes the proper time back to the now-powered SRAM.

BIOS clock resetting to a default date after every power cycle

When the CMOS cell drops below 2.8V, it can no longer hold the RTC circuit during a full power-off. The Aspire 5570 BIOS then falls back to a hardcoded default date — typically January 1, 2000 or similar — on every cold boot. Swapping the cell restores retention voltage. After the swap, set the correct date and time in BIOS and save before exiting.

CMOS checksum error on boot after fitting the new cell

A checksum error immediately after a cell swap usually means the BIOS read corrupted or blank SRAM — the previous cell was fully depleted long enough for SRAM contents to decay completely. The new cell restores power to the circuit, but BIOS still detects the invalid checksum from the cleared data. Enter BIOS setup, load defaults, set the correct date and time, then save and exit to write a valid checksum.