Clock

[IHOXOHI]

Hi,
It seems that to keep the time correctly, the best way could be to use a battery...
I presume that there is a relationship with the clock of the processor... And performances...
After used for long time like this with stm32 system, I'm questioning about the lifetime of the battery... It seems that if there isn't a lot of disconnection, nothing to say, but if I disconnect several times, the battery doesn't work quickly... Sometimes, I have noted that after disconnect, the board continue...? From the clock-battery???
I will try to use a big capacitor like a clock-battery...

Is it possible to connect a mechanical system for keep time like a watch? I have an old watch which works with moving...
Thanks.
....
I tested... It works just with a capacitor, but I have to connect the 3v3 to the capacitor too, to charge it...
Is there anything else which could be use, better than a capacitor?