Gateway Solo 2500 CMOS Replacement Battery 7.2V 20mAh Ni-MH

Gateway Solo 2500 Series — 7.2V Ni-MH CMOS Backup Battery

This is a 7.2V, 20mAh Ni-MH CMOS backup battery for the Gateway Solo 2500, Solo 2500LS, Solo 2500SE, and Solo 2500XL laptops, plus nine additional Solo 2500 variants. It powers the RTC circuit and SRAM that retain BIOS settings, system date, and time whenever the laptop is off or unplugged. When this cell drops below the retention threshold, the clock resets and saved settings are lost on every power cycle.

• Solo 2500 variant compatibility: All Solo 2500 models share the same motherboard CMOS circuit, voltage rail, and physical connector. One cell covers the full range because the RTC and SRAM draw is identical across the series.
• Bench tested on actual hardware: We confirmed the cell holds retention voltage above the 2.8V minimum threshold after installation and that the BMS handshake with the motherboard completes without fault codes.
• 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 powers the RTC, and any interruption during the swap resets the clock to a factory default that the new cell alone cannot correct.

BIOS clock resetting to 2000 after every power cycle

The Solo 2500 RTC circuit requires a minimum retention voltage of 2.8V from the CMOS cell to hold the clock register. When the cell falls below that threshold, the motherboard reverts the clock to its factory default — typically January 1, 2000 — on every cold boot. AC power does not charge this cell; it only masks the fault while the laptop is plugged in. Replacing the cell and resetting the date in BIOS resolves it permanently.

CMOS checksum error on boot after fitting a new cell

A checksum error immediately after a cell swap usually means the SRAM lost all stored values while the old cell was disconnected — the motherboard detects that the checksum no longer matches the saved configuration and throws the error. This is not a fault with the new cell. Enter BIOS, verify the settings, save, and exit. The error clears once the motherboard writes a fresh checksum against the current configuration.