This question already has an answer here:
I have this electronics that uses 3V rechargeable coin cell battery (ML2032) to power the RTC when the system is off. When the system is powered on it'll trickle charge the battery instead.
I'm looking for ways to allow the usage of regular non-rechargeable CR2032 battery instead. One way I see people doing on Amiga, which also uses 3V rechargeable battery, is to simply add a Schottky diode in series. However, I wonder if there is something even better. To me a voltage drop of at least 0.15V is a lot for a 3V battery.