Acer TravelMate 3200 CMOS Battery 3V 40mAh Lithium

Acer TravelMate 3200 Series — 3V Lithium CMOS Backup Battery

This is a 3V, 40mAh lithium coin cell that replaces the CMOS backup battery on the Acer TravelMate 3200, TravelMate 3202 XCi, 5920, and 5920G motherboards. It powers the real-time clock circuit and retains BIOS settings when mains power is removed. When the original cell depletes, the system loses stored configuration on every power cycle.

• TravelMate 3200 and 5920 series fit: These models share the same motherboard footprint and CMOS retention circuit voltage requirement. The RTC and SRAM on each board draw from the same coin cell socket, which is why one cell covers all four listed variants.
• Bench tested on actual hardware: We ran this cell against the RTC circuit and confirmed the BMS holds above 2.8V — the minimum retention voltage the CMOS SRAM requires to maintain stored settings without corruption or checksum errors on boot.
• Post-install BIOS step: After fitting the new cell, enter BIOS immediately and set the correct date and time, then save and exit. The CMOS circuit resets the clock to a factory default on any power interruption — the new cell will hold your corrected settings from that point forward.

BIOS clock resetting to 2000 after every power cycle

The RTC circuit on the TravelMate 3200 motherboard needs a minimum of 2.8V from the CMOS cell to retain the clock value when mains power is absent. Once the original cell drops below that threshold, the RTC loses its reference and reverts to a hardcoded default — typically 1 January 2000. This happens even if the main battery is fully charged, because the CMOS cell is a separate, non-rechargeable circuit. Replacing the coin cell and resetting the date in BIOS resolves this entirely.

CMOS checksum error on boot after fitting the new cell

A checksum error after a fresh coin cell install usually means the CMOS SRAM was fully drained before the swap — the stored configuration checksum no longer matches the data. The new cell restores power to the circuit, but the corrupted or blank SRAM still triggers the mismatch at POST. Enter BIOS setup, load default settings, then manually reconfigure boot order and any custom settings before saving. The checksum recalculates on save and the error clears on the next boot.