Amazon.com: MakerFocus Raspberry Pi RTC Module DS1307 Real Time Clock Module with BAT and Coin Battery for Raspberry Pi : Electronics
Amazon.com: 5pcs Tiny RTC I2C modules 24C32 Memory DS1307 Clock RTC Module Without Battery New : Electronics
The RTC battery on my boktai game had died recently and needed a new one soldered on. Sometimes I get a little nervous when the game is worth $100+ : r/Gameboy
MakerFocus DS3231 RTC Module Raspberry pi Real Time Clock Module with