http://helloacm.com/automatically-synchronize-date-and-time-on-8-bit-bbg-famiclone-using-db25-cable-to-connect-to-pc/ (http://helloacm.com/automatically-synchronize-date-and-time-on-8-bit-bbg-famiclone-using-db25-cable-to-connect-to-pc/)
Now, without CMOS-like battery, on every startup, you always have a correct time and date!
Just you need a cable and a PC. On each startup ::)
Is time feature really needed on famicom? If so, i'd add RTC chip to the basic cart
:)
synchronize once and don't power off