Fujitsu LifeBook S-4510 7.2V Ni-MH CMOS Replacement Battery

Fujitsu LifeBook S-4510 / S-4530 — 7.2V Ni-MH CMOS Backup Battery

This is the 7.2V, 40mAh Ni-MH CMOS backup battery for the Fujitsu LifeBook S-4510 and S-4530 series laptops. It sits on the motherboard and keeps system settings, BIOS configuration, and the real-time clock alive when mains power is removed. When this cell depletes, the laptop loses its date, time, and stored settings on every power cycle.

• LifeBook S-4510 and S-4530 fit: Both series share the same motherboard battery connector, voltage rail, and CMOS circuit layout. The 7.2V Ni-MH cell feeds the RTC and SRAM directly — neither series accepts a coin cell substitute without modification.
• Bench tested on actual hardware: We ran this cell against the CMOS circuit and confirmed the BMS handshake completes correctly. The cell held retention voltage above the 2.8V minimum threshold throughout the test cycle and maintained SRAM state without mains power present.
• After installation — enter BIOS immediately: The CMOS cell powers the RTC circuit. Any power interruption during the swap resets the clock to a factory default date. Once installed, boot into BIOS, set the correct date and time, then save and exit before returning to normal operation.

BIOS clock resetting to year 2000 after every power cycle on the S-4510

The LifeBook S-4510 RTC circuit requires the CMOS cell to stay above 2.8V to retain clock data. Once the cell drops below that threshold, the RTC loses its reference and falls back to the factory default timestamp — typically January 1, 2000 — on every cold boot. A depleted cell often still allows the laptop to POST normally, so the clock reset is the first visible sign of cell failure. Replacing the cell and resetting the date in BIOS resolves this immediately.

CMOS checksum error on boot after replacing the backup cell

A checksum error after a cell swap usually means the BIOS ran a settings verification against an empty CMOS — the old depleted cell left nothing valid stored, and the new cell powered up a blank SRAM. The BIOS flags this because the stored checksum no longer matches the current configuration. Boot into BIOS setup, load the default settings, set the correct date and time, then save and exit. The error clears on the next boot once a valid checksum is written to CMOS.