BIOS losing settings

I have encountered this on two different desktops; want to ask whether you also have encountered.

After transportation, the BIOS lost its settings, in particular, the boot settings. The lithium battery on motherboard was fresh in both cases after transportation.

Maybe the battery came loose during the transportation? Or there is something else I don’t know about?

Maybe the battery was jolted and temporarily lost contact so the CMOS memory on the motherboard lost its contents?

Is it true that the BIOS will lose its settings unconditionally, once the battery is disconnected for some time?

Yes. If the battery is removed momentarily, the BIOS will reset to default.

The default settings are stored on the BIOS chip. Any settings you apply are stored in volatile RAM and must have power applied to maintain those settings. Any time power is lost,(battery removed) the RAM loses all the settings. That battery is only there to keep those settings in RAM and keep the clock up.

But I remember the manual of a motherboard saying that in order to reset the motherboard (which may be more than resetting the BIOS), not only the battery should be removed, but two pins on the motherboard shall be shortened for 10 seconds.

Why do they want to connect the two pins?

To drain the capacitors. Sometimes the caps will give it enough current to keep the RAM powered up for a while. Sometimes, it will lose the memory instantly. They tell you to do that so that it guarantees to clear the RAM.

I see. They cannot afford to have a discharge resistor on the capacitor.

Thanks.