Fujitsu LifeBook C1010 CMOS Replacement Battery 3V 200mAh

Fujitsu LifeBook C1010 / S6010 Series — 3V Lithium CMOS Backup Battery

This is a 3V 200mAh lithium coin cell that powers the real-time clock and SRAM on the Fujitsu LifeBook C1010, C1020, S2020, and S6010 motherboards. When this cell drops below the retention threshold, the BIOS loses all stored settings and the clock resets on every power cycle. It is a non-rechargeable cell — replace it, do not attempt to charge it.

• LifeBook C1010 / C1020 / S2020 / S6010 compatibility: These models share the same RTC circuit layout and coin cell footprint. The cell sits on the motherboard and feeds the CMOS SRAM directly — same retention voltage requirement, same connector or contact-spring mount across the series.
• Bench tested on actual hardware: We seated this cell in the contact spring and measured output at 3.0V under the RTC standby load. The CMOS retained BIOS settings and clock data through a full mains power removal with no reset observed.
• Post-install BIOS step for the LifeBook RTC circuit: 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 on installation — it will not self-correct, and the wrong system clock will persist until you manually update it in BIOS.

BIOS clock resetting to year 2000 after every power cycle on the LifeBook C1010

The LifeBook C1010 RTC circuit requires the CMOS cell to hold at least 2.8V to maintain the clock and SRAM contents. Once the cell drops below that threshold, the circuit loses retention the moment mains power is cut. Every cold boot returns the clock to a default date — typically January 1, 2000 — because the RTC has no valid state to read. Replacing the cell stops the reset cycle, but the clock must still be set manually in BIOS after the swap, then saved.

CMOS checksum error on boot after fitting a new coin cell

A checksum error after a new cell install usually means the CMOS SRAM lost all data before the replacement — the stored checksum no longer matches the stored settings. This is not a fault with the new cell. Enter BIOS setup, load defaults, reset the date and time to the correct values, then save and exit. The checksum recalculates on a clean save, and the error will not reappear on the next boot provided the new cell is seated correctly and reading at or above 3.0V.