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Fujitsu lifebook s4572 - not retaining CMOS settings

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First post, by kotel

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Hi,

Recently my fujitsu lifebook s4572 (which is pretty beat up) stop to retain CMOS data (only did with the main battery plugged in which is beyond dead now).
Opened it up just to find two different batteries. One 7.2V varta Ni-MH one, one CR2032 3V on the mainboard. The varta has leaked (and is fully dead) so I rubbed vinegar on the corrosion on PCB and left it as is (only a few VIAs which don't look to be responible for RTC stuff, only the cell charging). The CR2032 was dead, so I've replaced it.

Sadly, the laptop still doesn't retain any settings (even after a reboot). Not even with the main battery.
Any ideas? I get the 3V from the CMOS battery onboard.

Last edited by kotel on 2025-09-19, 20:32. Edited 1 time in total.

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Reply 1 of 3, by bertrammatrix

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You are saying the 7.2 volt varta battery is still good?

Reply 2 of 3, by kotel

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No, the 7.2v is dead (already corrected the mistake). Don't see why it not being there would cause the CMOS not to store settings 😒

"I can believe I'm saying this, but...
Look alive people! Rest now and we die... Let's move."
- Aradus

Reply 3 of 3, by bertrammatrix

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Well there certainly wouldn't be a battery there for no reason 😀

My guess is that the cr2032 is there just for the clock and the varta to keep settings. Disconnect the diode that would have charged it, ditch the varta and try connecting two cr2032's in series (you can get a holder) instead of it.

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